Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_104_библиотеки_им_акад_М_И_Перельмана
.pdf
The molecular basis ofbone marrow failure syndromes andred cell enzymopathies 163
https://t.me/med1917
analysis may be required in equivocal cases. Prenatal diagno-
sis of at- risk fetuses is also feasible, by amniotic fluid or cho-
rionic villi sampling, followed by molecular testing of the
PKLR gene.
Management. Until the advent of allosteric activators
(seebelow), the mainstay of therapy for PK deficiency was
supportive, with phototherapy and/or exchange transfusion
in the newborn period, and regular or intermittent red cell
transfusions in children and adults. Iron chelation is
sometimes recommended even in patients who are not
transfusion dependent because with PK deficiency, there is a
propensity for iron overload. Splenectomy (invariably total)
can help to reduce transfusion requirement. In severe cases,
provided there are no systemic manifestations other than
hemolytic anemia, bone marrow transplantation can be con-
sidered. Of course, it should be carried out, if at all, before
there is organ damage (e.g. from iron overload).
The development of more specific therapies has been
guided by structural analysis of the PKR enzyme. Mitapivat
(AG- 348), is a novel first- in- class small molecule, that has
been designed to bind to the allosteric FBP site of PKR so as
to simulate activation by FBP, and thus functionally restore
the activity of a mutant enzyme to a normal or near- normal
level. In clinical trials, this orally administered small molecule
resulted in clinically meaningful improvement in nearly 50%
of patients with PK deficiency, in some cases with normalization of the hemoglobin level and markers of hemolysis.
Patients with at least one missense mutation had a higher
likelihood of a hemoglobin response. None of the patients
with two drastic mutations or from the Amish community
(homozygous R479H variant) had a hemoglobin response
suggesting that a minimum amount of full- length PK
protein is required for activation by mitapivat. Mitapivat
is now FDA- approved and recommended in individuals
with PKD of all ages, particularly those with at least one
missense mutation.
Glucose 6- phosphate dehydrogenase deficiency
G6PD deficiency is by far the most common abnormality
occurring in the pentose phosphate pathway. It affects 200–
300million individuals worldwide, with a high prevalence in
populations of Africa, southern Europe, the Middle East,
Southeast Asia, and parts of Oceania, as well as in regions to
which migrations from these areas have taken place. The
overall geographic distribution of G6PD deficiency and its
heterogeneity, together with clinical field studies and invitro
culture experiments, strongly support the view that this
common genetic trait has been selected by Plasmodium falci-
parum malaria, by virtue of the fact that it confers relative
resistance against this highly lethal infection. Delineation of
the molecular mechanism underlying this resistance could
be used to develop new approaches to protect G6PD-
normal
individuals against malaria.
Clinical features: Three types of clinical presentation are well
characterized.
1 The vast majority of G6PD- deficient people are asymptomatic
most of the time, but they are at risk of developing acute hemolytic anemia (AHA), which may be triggered by drugs (e.g. primaquine, rasburicase), infections, or ingestion of fava beans.
2 The risk of developing neonatal jaundice is much greater in
G6PD- deficient than in G6PD- normal newborns. This isof
great public health importance because untreated severe neonatal jaundice can lead to permanent neurological damage.
3 CNSHA: In contrast to the first two, this clinical presentation is very rare. The clinical picture is rather similar to
CNSHA associated with glycolytic enzymopathies (see
above) and again it is of variable severity. However, the
hemolysis is characteristically exacerbated by the same
agents that can cause acute hemolytic anemia in people with
the ordinary type of G6PD deficiency.
Diagnosis In individuals with clinically apparent G6PDdeficiency (type 3 above), the anemia is usually normocytic
and normochromic, and its severity ranges from moderate to
extremely severe. The morphology of red cells is not characteristic (non- spherocytic). AHA (in G6PD deficiency of type 1
above) is due largely to intravascular hemolysis, and hence is
associated with hemoglobinemia and hemoglobinuria. Here
the blood film shows instead rather spectacular evidence of
hemolysis in the guise of anisocytosis, polychromasia, spherocytes, bite cells, blister cells, and hemighosts. Supravital staining reveals the presence of Heinz bodies, consisting of
precipitates of denatured hemoglobin. Definitive diagnosis
relies on the direct demonstration of decreased activity of
G6PD in red cells by an appropriate enzyme assay. Of note,
during an acute crisis, the level of enzyme may be overestimated due to reticulocytosis, while at the same time, the oldest
(most G6PD deficient) red cells have been destroyed.
Molecular genetics G6PD is a homodimeric or homotetrameric molecule, and its single subunit is encoded by an
X-
linked gene that maps to Xq28. The tetramer, a dimer or
the dimer, is in equilibrium with the dimer itself. Of the
187mutations reported in the G6PD gene, most are point
mutations causing single amino acid substitutions. It is
therefore likely that complete absence of G6PD would be
lethal. This has been proven in the mouse (see below).
Asaresult of the phenomenon of X- chromosome inactivation in somatic cells (Lyonization), women heterozygotes are
genetic mosaics, in whom approximately one- half of the red
cells are normal and approximately one- half are G6PD deficient. However, there is a wide distribution around this
mean, and in some cases, the skewing is extreme. Therefore
本书版权归John Wiley & Sons Inc.所有
164 Molecular Hematology
https://t.me/med1917
clinical manifestations, such as favism, can occur in both
hemizygous men and heterozygous women, but they tend to
be milder in the latter, roughly in proportion to the fraction
of red cells that are G6PD- deficient. This correlation between
enzyme activity and clinical phenotype has been formally
demonstrated in a study of 200 heterozygous children
exposed to dapsone.
Function of G6PD In intermediary metabolism G6PD is aptly
depicted as the first step in the pentose phosphate pathway.
However, several lines of evidence indicate that its most
essential role is not to produce pentose, but rather to provide
reductive potential in the form of NADPH. NADPH is necessary for the replenishment of GSH when it is oxidized by
reactive oxygen species (ROS). These are generated endogenously, all the time in the course of deoxy hemoglobin
cycling, at a low rate; and at a much higher rate from the
metabolism of pro- oxidant compounds, such as primaquine
or substituted pyrimidines present in fava beans. In G6PD
normal red cells NADPH production is stepped up in
response to ROS; in G6PD deficient red cells ROS result in
GSH depletion and subsequent red cell damage (oxidative
hemolysis). G6PD- null mouse embryos have been obtained
through targeted inactivation of G6PD in embryonic stem
cells. From a detailed analysis of hemizygous mutant
embryos, who die by day 10.5, it was inferred that the cause
of death is precisely the onset of aerobic metabolism, confirming the non- redundant role of G6PD in protection
against oxidative stress. Interestingly, heterozygous embryos
also die, somewhat later, only if their G6PD- null gene is of
maternal origin. In this case, the cause of death is a defective
placenta, as a consequence of the selective inactivation of the
paternal X chromosome in extra- embryonic tissues.
Molecular pathophysiology Acute hemolytic anemia is seen
with most of the variants of G6PD, whereby red cells retain
some 10% of normal G6PD activity, resulting in a limited
capacity of these cells to withstand the oxidative action of an
exogenous factor. In contrast, in a subset of variants (referred
to as class I variants), the steady-
state level of G6PD is so
lowthat it becomes limiting for red cell survival, even in the
absence of any oxidant challenge: the result is CNSHA.
Numerous point mutations in the G6PD gene causing
CNSHA have been identified (Figure 11.2); interestingly,
some individual mutations appear to have arisen independently more than once, since they have been observed in
cases from distinct geographical areas. With the majority of
mutations, G6PD deficiency is caused, at the biochemical
level, by decreased stability of the enzyme, that is a marked
acceleration of the physiological decay of G6PD and of many
other cytoplasmic proteins as erythrocytes age. With a few
mutations, G6PD deficiency is caused instead by decreased
catalytic activity or altered substrate affinity. Although we
cannot explain the reason for a severe clinical phenotype in
every case, a cluster of mutations causing CNSHA in exons
10 and 11 corresponds closely to the region of the molecule
where the two subunits interface. Dimerization is essential
for enzyme activity, and it is not surprising that amino acid
replacements in this region will interfere with dimer formation or cause marked instability of the dimer.
Enzyme testing versus DNA testing Given that nowadays
many laboratories are more geared to PCR-
based technologies than to enzyme assays, it is tempting to diagnose G6PD
deficiency by simply testing for underlying mutations.
Thisisperfectly feasible, especially in areas where prevalent
mutations are known. However, when no mutation is found
this approach is not definitive because a known mutation
unexpected in that area, or a novel mutation would be
missed. DNA testing is certainly the best way to detect all
heterozygotes. However, it will tell us nothing about skewing
of X- chromosome inactivation, and therefore, it will not predict the risk and severity of acute hemolytic anemia in a heterozygote. For these reasons, measurement of red cell G6PD
activity is still necessary to inform clinical decision- making.
The need, that has emerged in many parts of the world, to
test for G6PD deficiency before administering primaquine
for definitive treatment of Plasmodium vivax malaria, has
prompted very recently the development of “point of care”
G6PD assays requiring practically no laboratory facilities.
Management The commonest manifestations of G6PD deficiency, neonatal jaundice, and acute hemolytic anemia, are
largely preventable or controllable by screening, surveillance,
and avoidance of triggering factors, particularly fava beans,
by G6PD deficient subjects. One of the current challenges is
to develop a good animal model that will allow preclinical
testing of new drugs to assess whether they are likely to cause
AHA in G6PD- deficient individuals. When a patient presents with acute hemolytic anemia, and once the cause is
diagnosed, no specific treatment may be needed if the episode is mild. At the other end of the spectrum, and especially
in children, acute hemolytic anemia may be a medical emergency requiring immediate blood transfusion. The management of neonatal jaundice does not differ from that of
neonatal jaundice due to causes other than G6PD deficiency
and, in order to prevent neurological damage, treatment with
phototherapy and/or exchange blood transfusion may be
required. The management of CNSHA is similar to that of
CNSHA due to glycolytic enzymopathies, but in addition it is
important to avoid exposure to potentially hemolytic drugs.
Again, although there is no evidence of selective red cell
destruction in the spleen (as seen in hereditary spherocytosis), splenectomy has proven beneficial in severe cases.
Recent advances in molecular biology offer the possibility of novel therapies for this common disease. First, lifelong expression of human G6PD at therapeutic levels has
been obtained in red blood cells and in white blood cells of
本书版权归John Wiley & Sons Inc.所有
The molecular basis ofbone marrow failure syndromes andred cell enzymopathies 165
1 kb
m h
i
S s
z Aa
(A)
(B)
Mahidol; Chatham; Coimbra; Seattle; Santamaria; Aures; Cosenza; A-(968C).
https://t.me/med1917
1 2 34 5678 910111213
100bp
A
a
Union; Canton; Mediterranean; A-(202A); Kaiping; Taipei; Viangchan;
U
Figure 11.2 Distribution of mutations along the human G6PD gene (Xq28). (A) Genomic structure of the human G6PD gene. Exons 1–13
are shown as numbered rectangles (black rectangles represent coding sequences; shaded rectangles represent non- coding sequences).
(B)Thelocations of amino acid substitutions are shown along the coding sequence of the gene, in which the exons are shown as open boxes.
Substitutions giving rise to the more severe sporadic (class I) variants are shown as filled circles below. Small deletions, a nonsense mutation, and a
splice site mutation are shown as filled rectangles, a cross and ∫, respectively. The milder class II and class III variants are shown as open circles
above; proven polymorphic variants are shown as a letter in a colored circle. Class IV variants are shown as open ellipses. All variants shown result
in G6PD deficiency, except G6PDA. From Luzzatto L, Mehta A, Vulliamy T. (2001) Glucose- 6- phosphate dehydrogenase deficiency. In: Scriver CR,
Beaudet AL, Sly WS, Valle D (eds). The Metabolic and Molecular Basis of Inherited Disease, 8th edn. NewYork: McGraw- Hill, pp.4517–4553,
withpermission.
C
M
m
S
t
i
M
A
S
k t v
A
v
h
U
k
C
z
111098765432 13
12
X
mice through retroviral- mediated transfer into HSCs.
Second, in human G6PD- deficient cells (class I- III variants), restoration of G6PD activity has been achieved
invitro using histone deacetylase inhibitors (HDACi). This
effect is mediated by histone hyperacetylation at the G6PD
promoter resulting in increased transcription, protein level,
and enzymatic activity of the mutant protein. Interestingly
HDACi do not exert thiseffect on all genes within the glycolytic pathway, rather
transcription of G6PD is selectively
upregulated. Further understanding of the mechanism of
action of HDACi and other epigenetic modifiers could
therefore open up therapeutic opportunities in other diseases in which missense mutations result in an enzymatic
deficiency.
Pyrimidine 5′- nucleotidase deficiency
Nucleotide metabolism in red blood cells is necessary for the
maintenance of ATP and GTP levels. Deficiency of pyrimidine 5′- nucleotidase, involved in pyrimidine metabolism, is
of interest for several reasons. First, it is probably the third
most common red cell enzymopathy (trailing G6PD and PK
deficiencies). Second, the diagnosis can be suspected from
red cell morphology because it is associated with basophilic
stippling (accounted for by the accumulation of RNA in
mature red cells). Third, although we do not really understand the precise mechanism, 5′- nucleotidase deficiency is a
good example of how the red cell has virtually only one way
to manifest it is suffering– almost any metabolic abnormality will lead to accelerated destruction (i.e. hemolysis).
Fourth, the anemia of chronic lead poisoning (which had
been known for a long time to be associated with basophilic
stippling) turns out to be the consequence of the fact that
lead isa powerful inhibitor of 5′-
nucleotidase; thus in terms
of itshematological effects, lead poisoning is a phenocopy of
5′- nucleotidase deficiency.
Since mapping of the pyrimidine- 5′- nucleotidase gene
(NT5C3) to chromosome 7in 2001, 24 different mutations,
most commonly in homozygosity, have been identified in
just over 30 unrelated families with 5′- nucleotidase deficiency. Mutations include missense, nonsense, alterations of
splicing sites, insertions and deletions, and diagnosis is by
molecular testing. 5′- nucleotidase deficiency has also been
associated with hemoglobin E, hemoglobin D Punjab,
本书版权归John Wiley & Sons Inc.所有
166 Molecular Hematology
https://t.me/med1917
and spectrin deficiency. In the former case, concurrent
5′- nucleotidase deficiency made the clinical expression of
HbE disease more severe.
Investigation of a father and daughter pair affected by
5′- nucleotidase deficiency, in which the father had a more
severe disease phenotype, revealed that the father was
homozygous for a polymorphism in the TATAA element of
the promoter region in the uridine diphospho glucuronosyl
transferase 1A (UGT1A) gene (TA7/TA7) while the daughter was heterozygous (TA6/TA7). This polymorphism, usually associated with benign Gilbert’s syndrome, contributed
to more severe hemolysis in the father. Such a case illustrates
the value of molecular characterization of multiplex families
affected by a disease primarily regarded as monogenic, with
the aim of identifying disease- modifying epistatic factors
that contribute to clinical heterogeneity and that could be the
target of therapeutic intervention.
Concluding remarks
Since the last edition of this volume, advances in different
areas of biology have already impacted the diagnosis and
treatment of BMF and hemolytic anemias. In AA, the impressive therapeutic success of the TpoR agonist eltrombopag
promises to offer a simple and effective therapeutic option
for patients that are not candidates for allogeneic stem cell
transplantation.
In inherited BMF syndromes, the ease of genetic diagnosis
by next- generation sequencing of multi- gene panels already
offers accurate and swifter diagnosis for patients and their
families allowing for appropriate management decisions, for
example selection of disease- free familial donors for hematopoietic stem cell transplantation and in many instances prenatal diagnosis and counseling. Whole genome sequencing
has also led to the identification of new and rare disease entities allowing more precise genetic diagnosis of anemia and
bone marrow failure, and the future prospect of targeted
therapies.
In PNH, the success of eculizumab has spurred the
development of a new generation of complement inhibitors.
Because these molecules target the proximal components of
complement, they are expected to be more effective in controlling extravascular hemolysis (regularly seen in patients
on eculizumab and ravulizumab) as well as intravascular
hemolysis, and some could be administered orally.
Gene editing technologies, in particular CRISPR/Cas9based gene correction, offer a more realistic hope than ever
before for gene therapy, in principle, for any monogenic disorder, such as those covered in this chapter.
Increasing knowledge of epigenetic mechanisms of how
gene transcription is regulated and relevant mechanistic
studies focused on genes associated with heritable BMF and
hemolytic anemias also promises to lead to new therapies.
The case of restoring G6PD activity in G6PD- deficient cells
by simply enhancing transcription of the mutant allele using
HDAC inhibitors provides the proof- of- concept for a novel
and simple notion. Transcriptional up- regulation of mutant
gene alleles has significant therapeutic potential, both in the
case of missense mutation- associated enzymopathies with
respect to the wild- type allele, and in the case of diseases due
to haploinsufficiency. Exploration of this approach will be
greatly facilitated by the advent of a plethora of epigenetic
drugs, beyond HDAC inhibitors.
Since the last edition, small molecules acting as allosteric
activators have been introduced for the treatment of glycolytic enzymopathies.
Therefore, it is realistic to expect that when this chapter is
due to be updated again, more patients with bone marrow
failure syndromes and with hemolytic anemias will have
benefited from novel and effective treatments based on a
deeper understanding of the molecular pathogenesis of the
respective diseases.
Further reading
Bone marrow failure syndromes
Aplastic anemia
Peffault de Latour, R., Kulasekararaj, A., Iacobelli, S. etal. (2022). Severe
aplastic anemia working party of the European Society for blood and
marrow transplantation. Eltrombopag added to immunosuppression
in severe aplastic anemia. N. Engl. J. Med. 386 (1): 11–23.
Killick, S.B., Bown, N., Cavenagh, J. etal. (2016). Guidelines for the
diagnosis and management of adult aplastic anaemia. Br. J. Haematol.
172: 187–207.
Young, N.S. (2002). Acquired aplastic anaemia. Ann. Intern. Med.
136:534–546.
Young, N.S. and Barrett, A.J. (1995). The treatment of severe acquired
aplastic anaemia. Blood 85: 3367–3377.
Young, N.S. and Maciejewski, J. (1997). The pathophysiology of
acquired aplastic anaemia. N. Engl. J. Med. 336: 1365–1372.
Young, N.S., Scheinberg, P., and Calado, R.T. (2008). Aplastic anaemia.
Curr. Opin. Hematol. 15: 162–168.
Desmond, R., Townsley, D.M., Dumitriu, B. etal. (2014). Eltrombopag
restores trilineage haematopoiesis in refractory severe aplastic anaemia that can be sustained on discontinuation of drug. Blood 123 (12):
1818–1825.
Marsh, J.C. and Mufti, G.J. (2016). Clinical significance of acquired
somatic mutations in aplastic anaemia. Int. J. Hematol. 104 (2):
159–167.
Nishimura, J., Yamamoto, M., Hayashi, S. etal. (2014). Genetic variants
in C5 and poor response to eculizumab. N. Engl. J. Med. 370 (7):
632–639.
本书版权归John Wiley & Sons Inc.所有
The molecular basis ofbone marrow failure syndromes andred cell enzymopathies 167
https://t.me/med1917
Paroxysmal nocturnal hemoglobinuria
Luzzatto, L. (2022). Management of paroxysmal nocturnal hemoglobi-
nuria (PNH). J. Clin. Lab. Anal. 36 (12): e24770.
Notaro, R. and Luzzatto, L. (2022). Breakthrough hemolysis in PNH
with proximal or terminal complement inhibition. N. Engl. J. Med.
387 (2): 160–166.
Hillmen, P., Szer, J., Weitz, I. etal. (2021). Pegcetacoplan versus eculi-
zumab in paroxysmal nocturnal hemoglobinuria. N. Engl. J. Med.
384 (11): 1028–1037.
Kelly, R.J., Höchsmann, B., Szer, J. etal. (2015). Eculizumab in pregnant
patients with paroxysmal nocturnal hemoglobinuria. N. Engl. J. Med.
373 (11): 1032–1039.
Almeida, A.M., Murakami, Y., Layton, D.M. etal. (2006). Hypomorphic
promoter mutation in PIGM causes inherited glycosylphosphatidylinositol deficiency. Nat. Med. 12: 846–851.
Araten, D.J., Nafa, K., Pakdeesuwan, K., and Luzzatto, L. (1999). Clonal
populations of haematopoietic cells with paroxysmal nocturnal
hemoglobinuria genotype and phenotype are present in normal individuals. Proc. Natl. Acad. Sci. U. S. A. 96: 5209–5214.
Hillmen, P., Young, N.S., Schubert, J. et al. (2006). The complement
inhibitor eculizumab in paroxysmal nocturnal hemoglobinuria.
N.Engl. J. Med. 355: 1233–1243.
Luzzatto, L., Bessler, M., and Rotoli, B. (1997). Somatic mutations in
paroxysmal nocturnal hemoglobinuria: a blessing in disguise?
Cell88: 1–4.
Takeda, J., Miyata, T., Kawagoe, K. etal. (1993). Deficiency of the GPI
anchor caused by a somatic mutation of the PIGmal nocturnal hemoglobinuria. Cell 73: 703–711.
Gargiulo, L., Papaioannou, M., Sica, M. et al. (2013).
Glycosylphosphatidylinositolparoxysmal nocturnal hemoglobinuria. Blood 121 (14): 2753–2761.
Belet, S., Fieremans, N., Yuan, X. etal. (2014). Early frameshift muta-
tion in PIGA identified in a large XLID family without neonatal
lethality. Hum. Mutat. 35 (3): 350–355.
Krawitz, P.M., Höchsmann, B., Murakami, Y. et al. (2013). A case of
paroxysmal nocturnal hemoglobinuria caused by a germline mutation and a somatic mutation in PIGT. Blood 122 (7): 1312–1315.
specific, CD1d- restricted T cells in
A gene in paroxys-
Fanconi anemia
Río, P., Navarro, S., Wang, W. et al. (2019). Successful engraftment of
gene- corrected hematopoietic stem cells in non- conditioned patients
with Fanconi anemia. Nat. Med. 25 (9): 1396–1401.
Wang, M., Brandt, L.T.L., Wang, X. et al. (2023). Genotoxic aldehyde
stress prematurely ages hematopoietic stem cells in a p53- driven
manner. Mol. Cell 83: 2417–2433.e7.
Alter, B. and Young, N.S. (1998). The bone marrow failure syndromes. In:
Nathan and Oski’s Hematology of Infancy and Childhood, 5ee (eds.D.G.
Nathan and S.H. Orkin), 237–335. Philadelphia: WBSaunders.
Andreassen, P.R., D’Andrea, A.D., and Taniguchi, T. (2004). ATR cou-
ples FANCD2 monoubiquitination to the DNA- damage response.
Genes Dev. 18: 1958–1963.
Cohn, M.A. and D’Andrea, A.D. (2008). Chromatin recruitment of
DNA repair proteins: lessons from the Fanconi anaemia and doublestrand break repair pathways. Mol. Cell 32: 306–312.
Garcia- Higuera, I., Taniguchi, T., Ganesan, S. etal. (2001). Interaction
of the Fanconi anaemia proteins and BRCA1 in a common pathway.
Mol. Cell 7: 249–262.
Howlett, N.G., Taniguchi, T., Olson, S. etal. (2002). Bi-
tion of BRCA2 in Fanconi anaemia. Science 297: 606–609.
Joenje, H. and Patel, K.J. (2001). The emerging genetic and molecular
basis of Fanconi anaemia. Nat. Rev. Genet. 2: 446–459.
Levitus, M., Waisfisz, Q., Godthelp, B.C. etal. (2005). The DNA helicase
BRIP1 is defective in Fanconi anaemia complementation group.
Nat.Genet. 37: 934–935.
Litman, R., Peng, M., Jin, Z. etal. (2005). BACH1 is critical for homolo-
gous recombination and appears to be the Fanconi anaemia gene
product FANCJ. Cancer Cell 8: 255–265.
Meetei, A.R., Medhurst, A.L., Ling, C. etal. (2005). A human ortholog
of archaeal DNA repair protein HEF is defective in Fanconi anaemia
complementation group M. Nat. Genet. 37: 958–963.
Mosedale, G., Niedzwiedz, W., Alpi, A. etal. (2005). The vertebrate Hef
ortholog is a component of the Fanconi anaemia tumourpathway. Nat. Struct. Mol. Biol. 12: 763–771.
Niedzwiedz, W., Mosedale, G., Johnson, M. etal. (2004). The Fanconi
anaemia gene FANCC promotes homologous recombination and
prone DNA repair. Mol. Cell 15: 607–620.
error-
Pichierri, P. and Rosselli, F. (2004). The DNA crosslink- induced S- phase
checkpoint depends on ATR–CHK1 and ATR–NBS1–FANCD2
pathways. EMBO J. 23: 1178–1187.
Strathdee, C.A., Gavish, H., Shannon, W.R., and Buchwald, M. (1992).
Cloning of cDNAs for Fanconi’s anaemia by functional complementation. Nature 356: 763–767.
Venkitaraman, A.R. (2004). Tracing the network connecting BRCA and
Fanconi anaemia proteins. Nat. Rev. Cancer 4: 266–276.
Wang, W. (2007). Emergence of a DNA- damage response network
consisting of Fanconi anaemia and BRCA proteins. Nat. Rev. Genet.
8: 735–748.
Wang, X., Andreassen, P.R., and D’Andrea, A.D. (2004). Functional
interaction of monoubiquitinated FANCD2 and BRCA2/FANCD1 in
chromatin. Mol. Cell. Biol. 24: 5850–5862.
Xia, B., Dorsman, J.C., Ameziane, N. etal. (2007). Fanconi anaemia is
associated with a defect in the BRCA2 partner PALB2. Nat. Genet.
39: 159–161.
Yamamoto, K., Ishiai, M., Matsushita, N. etal. (2003). Fanconi anaemia
FANCG protein in mitigating radiation- and enzyme- induced DNA
double- strand breaks by homologous recombination in vertebrate
cells. Mol. Cell. Biol. 23: 5421–5430.
Wang, A.T. and Smogorzewska, A. (2015). SnapShot: Fanconi anaemia
and associated proteins. Cell 160 (1–2): 354–354.e1.186.
Ameziane, N., May, P., Haitjema, A. et al. (2015). A novel Fanconi
anaemia subtype associated with a dominant- negative mutation in
RAD51. Nat. Commun. 6: 8829.
allelic inactiva-
suppressor
Dyskeratosis congenita
Revy, P., Kannengiesser, C., and Bertuch, A.A. (2023). Genetics of
human telomere biology disorders. Nat. Rev. Genet. 24 (2): 86–108.
Dokal, I., Tummala, H., and Vulliamy, T. (2022). Inherited bone marrow
failure in the pediatric patient. Blood 140 (6): 556–570.
本书版权归John Wiley & Sons Inc.所有
168 Molecular Hematology
https://t.me/med1917
DeBoy, E.A., Tassia, M.G., Schratz, K.E. et al. (2023). Familial clonal
hematopoiesis in a long telomere syndrome. N. Engl. J. Med.
388:2422–2433. epub ahead of print.
Niewisch, M.R., Giri, N., McReynolds, L.J. et al. (2022). Disease
progression and clinical outcomes in telomere biology disorders.
Blood 139 (12): 1807–1819.
Nagpal, N. etal. (2020). Small-
omerase activity in patient stem cells. Cell Stem Cell 26: 896–909.e8.
Autexier, C. and Lue, N.F.. The structure and function of telomerase
reverse transcriptase. Annu. Rev. Biochem. 75: 493–517.
Heiss, N.S., Knight, S.W., Vulliamy, J.T. etal. (1998). X-
tosis congenita is caused by mutations in a highly conserved gene
with putative nucleolar functions. Nat. Genet. 19: 32–38.
Kirwan, M. and Dokal, I. (2008). Dyskeratosis congenita: a genetic
disorder of many faces. Clin. Genet. 73: 103–112.
Mitchell, J.R., Wood, E., and Collins, K. (1999). A telomerase compo-
nent is defective in the human disease dyskeratosis congenita. Nature
402: 551–555.
Vulliamy, T., Marrone, A., Goldman, F. etal. (2001). The RNA compo-
nent of telomerase is mutated in autosomal dominant dyskeratosis
congenita. Nature 413: 432–435.
Jongmans, M.C., Verwiel, E.T., Heijdra, Y. et al. (2012). Revertant
somatic mosaicism by mitotic recombination in dyskeratosis
congenita. Am. J. Hum. Genet. 90: 426–433.
de la Fuente, J. and Dokal, I. (2007). Dyskeratosis congenita: advances
in the understanding of the telomerase defect and the role of stem
cell transplantation. Pediatr. Transplant. 11 (6): 584–594.
Jones, M., Bisht, K., Savage, S.A. etal. (2009). The shelterin complex and
haematopoiesis. J. Clin. Invest. 126 (5): 1621–1629.
Woo, D.H., Chen, Q., Yang, T.L. etal. (2016). Enhancing a Wnt-
feedback loop restores intestinal stem cell function in a human organotypic model of dyskeratosis congenita. Cell Stem Cell 19 (3):
397–405.
molecule PAPD5inhibitors restore tel-
linked dyskera-
telomere
Diamond–Blackfan anaemia
Draptchinskaia, N., Gustavsson, P., Andersson, B. et al. (1999).
Thegene encoding ribosomal protein S19 is mutated in Diamond–
Blackfan anaemia. Nat. Genet. 21: 169–175.
Iskander, D., Roy, N.B.A., Payne, E. et al. (2023). Diamond-
anemia in adults: in pursuit of a common approach for a rare disease.
Blood Rev. 8: 101097.
O’Donohue, M.F., Da Costa, L., Lezzerini, M. et al. (2022). HEATR3
variants impair nuclear import of uL18 (RPL5) and drive DiamondBlackfan anemia. Blood 139 (21): 3111–3126.
Iskander, D., Wang, G., Heuston, E.F. etal. (2021). Single- cell profiling
of human bone marrow progenitors reveals mechanisms of failing
erythropoiesis in Diamond(610): eabf0113.
Yang, Z., Keel, S.B., Shimamura, A. etal. (2016). Delayed globin synthe-
sis leads to excess heme and the macrocytic anemia of Diamond
Blackfan anemia and del(5q) myelodysplastic syndrome. Sci. Transl.
Med. 8 (338): 338ra67.
Clinton, C. and Gazda, H.T. (2009). Diamond- Blackfan anaemia. In:
GeneReviews® [Internet] (eds. R.A. Pagon, M.P. Adam, H.H. Ardinger,
etal.). Seattle (WA): University of Washington, Seattle. 1993–2016.
Blackfan anemia. Sci. Transl. Med. 13
Blackfan
Iskander, D., Psaila, B., Gerrard, G. etal. (2015). Elucidation of the EP
defect in Diamondspective isolation of human EPs. Blood 125 (16): 2553–2557.
Gerrard, G., Valgañón, M., Foong, H.E. etal. (2013). Target enrichment
and highto identify mutations associated with DiamondBr.J.Haematol. 162 (4): 530–536.
Sankaran, V.G., Ghazvinian, R., Do, R. etal. (2012). Exome sequencing
identifies GATA1 mutations resulting in Diamondmia. J. Clin. Invest. 122: 2439–2443.
De Keersmaecker, K., Atak, Z.K., Li, N. etal. (2013). Exome sequencing
identifies mutation in CNOT3 and ribosomal genes RPL5 and RPL10in
T-
throughput sequencing of 80 ribosomal protein genes
cell acute lymphoblastic leukaemia. Nat. Genet. 45 (2): 186–190.
Blackfan anaemia by characterisation and pro-
Blackfan the.
Blackfan anae-
Red cell enzyme deficiencies
Al- Samkari, H., Galactéros, F., Glenthøj, A. et al. (2022). Mitapivat
versus placebo for pyruvate kinase deficiency. N. Engl. J. Med.
386:1432–1442.
Beutler, E. (1994). Glucose-
N.Engl. J. Med. 324: 169–174.
Hirono, A., Kanno, H., Miwa, S., and Beutler, E. (2001). Pyruvate defi-
ciency and other enzymopathies of the erythrocyte. In: The Metabolic
and Molecular Basis of Inherited Disease, 8ee (eds. C.R. Scriver,
A.L. Beaudet, W.S. Sly, and D. Valle), 4637–4664. New York:
McGraw-
Grace, R.F., Zanella, A., Neufeld, E.J. etal. (2015). Erythrocyte pyru-
vate kinase deficiency: 2015 status report. Am. J. Hematol. 90 (9):
825–830.
Luzzatto, L., Mehta, A., and Vulliamy, T. (2001). Glucose- 6- phosphate
dehydrogenase deficiency. In: The Metabolic and Molecular Basis of
Inherited Disease, 8ee (eds. C.R. Scriver, A.L. Beaudet, W.S. Sly, and
D. Valle), 4517–4553. NewYork: McGraw-
Mentzer, W.C. (1998). Pyruvate kinase deficiency and disorders of gly-
colysis. In: Nathan and Oski’s Hematology of Infancy and Childhood,
5ee (eds. D.G. Nathan and S.H. Orkin), 665–703. Philadelphia: WB
Saunders.
Makarona, K., Caputo, V.S., Costa, J.R. etal. (2014). Transcriptional and
epigenetic basis for restoration of G6PD enzymatic activity in human
G6PD-
Luzzatto, L., Nannelli, C., and Notaro, R. (2016). Glucose-
dehydrogenase deficiency. Hematol. Oncol. Clin. North Am. 30 (2):
373–393.
Chiarelli, L.R., Morera, S.M., Galizzi, A. etal. (2008). Molecular basis of
pyrimidine 5′- nucleotidase deficiency caused by 3newly identified
missense mutations (c.187T& gt;C, c.469G& gt;C and c.740T& gt;C)
and a tabulation of known mutations. Blood Cells Mol. Dis. 40 (3):
295–301.
Pamba, A., Richardson, N.D., Carter, N. etal. (2012). Clinical spec-
trum and severity of hemolytic anaemia in glucose 6dehydrogenase- deficient children receiving dapsone. Blood 120 (20):
4123–4133.
Luzzatto, L. (2015). G6PD deficiency: a polymorphism balanced by
heterozygote advantage against malaria. Lancet Haematol. 2:
e400–e401.
Hill.
deficient cells. Blood 124 (1): 134–141.
6- phosphate dehydrogenase deficiency.
Hill.
6- phosphate
phosphate
本书版权归John Wiley & Sons Inc.所有
Chapter12
https://t.me/med1917
Anemia ofchronic disease
Tomas Ganz and Elizabeta Nemeth
Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
Introduction and definition, 169
General principles, 169
Diagnosis, 169
Pathogenesis, 170
Introduction and definition
Anemia of inflammation (less precisely referred to as
anemia of chronic disease) is the second most common
form of anemia (after iron deficiency) and is seen in the
setting of chronic infections, inflammatory disorders
including rheumatological conditions and inflammatory
bowel diseases, certain malignancies, and chronic kidney
diseases. A related form of anemia develops within days in
critically ill patients with sepsis or other acute conditions of
systemic inflammation. While the prevalence of iron deficiency in the industrialized countries is now decreasing,
anemia of inflammation would be expected to become
more prevalent as the number of elderly with chronic
inflammatory conditions continues to rise. The disorder
usually presents as a mild- to- moderate anemia, with erythrocyte morphology ranging from normocytic and normochromic to microcytic and hypochromic, depending on the
severity and duration of the underlying disease. Anemia of
inflammation is defined by inadequate erythrocyte production in the setting of low serum iron despite preserved or
even increased macrophage iron stores.
General principles
An essential pathogenic feature of this anemia is the iron
restriction of hemoglobin synthesis. Unlike iron- deficiency
anemia, the restriction is due to the slow release of iron from
stores rather than the absolute deficiency of total body iron.
Depending on the underlying disease, the anemia is variably
compounded by inflammatory cytokines causing decreased
production of erythropoietin, suppression of the erythroid
precursor proliferation and differentiation, and decreased
erythrocyte survival. In other situations, anemia of inflammation may be exacerbated by blood loss and true iron
Principles of treatment, 172
Future treatments, 173
Further reading, 173
deficiency. Several of these factors may contribute to the
pathogenesis of the extreme variant of the anemia that develops acutely in the critical care setting.
Diagnosis
Iron parameters
Hypoferremia, a decrease in serum iron concentration, is the
defining feature of anemia of inflammation. It develops
within hours of the onset of infection or severe inflammation. Synthesis of the iron- binding protein transferrin (measured directly or as total iron- binding capacity) is decreased,
unlike iron- deficiency anemia, where it is often increased.
The decrease in transferrin concentrations develops more
slowly than the decrease in serum iron levels because of the
longer half- life of transferrin (8–12days) compared with that
of iron (about 90 min).
Serum ferritin
Ferritin is found in blood plasma as a large multimer consisting mostly of glycosylated - ferritin subunits. Ferritin is
secreted by macrophages and hepatocytes, and its serum levels are increased in response to iron loading of these cells.
Systemic inflammation also increases ferritin synthesis and
secretion. Serum ferritin concentrations, reflecting inflammation and iron stores, are increased in anemia of inflammation and decreased in iron deficiency. Serum ferritin is thus
very useful in the differential diagnosis of patients with low
serum iron concentrations. However, depleted iron stores in
patients with coexisting inflammation may yield intermediate ferritin values, and then this test becomes less useful. In
this situation, iron deficiency should be suspected if ferritin
unexpectedly decreases below the patient’s usual baseline. It
has been suggested that serum transferrin receptor assay
may be helpful in differentiating iron deficiency anemia
Molecular Hematology, Fifth Edition. Edited by Drew Provan and Hillard M. Lazarus.
© 2024 John Wiley & Sons Ltd. Published 2024 by John Wiley & Sons Ltd.
本书版权归John Wiley & Sons Inc.所有
169
170 Molecular Hematology
https://t.me/med1917
from anemia of inflammation. Soluble transferrin receptor
(sTFR) is increased in iron deficiency, reflecting the posttranscriptional stabilization of transferrin receptor mRNA
by iron- regulatory proteins 1 and 2 during cellular iron deficiency, but sTFR can also be increased whenever erythroblast numbers increase as well as in inflammatory disorders,
where it may reflect iron restriction affecting erythrocyte
precursors. It is possible that the quantitative effects of
inflammation and iron deficiency on serum transferrin
receptor assay differ due to the differential effects of the two
processes on the erythroblasts, but this remains to be
explored experimentally and in larger human studies.
Bone marrow studies
Bone marrow aspiration or biopsy is now rarely necessary for
the diagnosis of anemia of inflammation. In general, the
bone marrow appears normal, unless the underlying disease
directly affects it. The most important information obtained
from marrow examination is the content and distribution of
iron, found as storage iron in the cytoplasm of macrophages
or as functional iron in nucleated red cell precursors. In normal individuals, several Prussian blue- staining particles are
seen in many macrophages, and about one- third of nucleated
red cells, called sideroblasts, contain blue inclusions. In iron
deficiency, both sideroblasts and macrophage iron are absent.
In contrast, in anemia of inflammation, sideroblasts are
fewer, but macrophage iron is increased. The increase in
storage iron in the face of decreased plasma iron and fewer
sideroblasts is characteristic of anemia of inflammation.
Although the bone marrow iron stain could be considered
the gold standard for the differential diagnosis of anemia of
inflammation and iron deficiency, the procedure causes
patient discomfort, can be confounded by differences in
interpreter skills and by the presence of poorly mobilizable
iron deposits from intravenous iron preparations, and so the
serum ferritin assay has largely replaced it.
Pathogenesis
Hypoferremia
Within hours of the onset of systemic infection or inflammation, plasma iron concentrations markedly decreased in both
humans and experimental animal models. This defensive
response, hypoferremia of inflammation, is thought to
restrict the availability of iron to extracellular microbes, limiting their proliferation during early phases of infection.
Recent studies indicate that non- transferrin- bound iron
(NTBI) is a particularly potent simulator of pathogen growth,
specifically of gram- negative bacteria and some fungi; thus,
elimination of NTBI may be the most important aspect of
hypoferremia as an innate immune response.
Hypoferremia of inflammation is mediated by inflammatory cytokines, including prominently interleukin (IL)-
6,
which increase rapidly in the first few hours of infection
and induce the synthesis of the iron- regulatory hormone
hepcidin. Hepcidin binds to the iron transporter ferroportin
on iron- exporting cells (macrophages, enterocytes, and
hepatocytes), causing occlusion, internalization, and degradation of ferroportin. Certain microbe- derived molecules
and cytokines can also directly decrease ferroportin mRNA
expression, further contributing to lower ferroportin protein
on the cell membrane. As a result of lesser synthesis and
greater degradation of ferroportin, iron efflux is diminished,
and the continuing consumption of iron depletes the extracellular iron pool (Figure12.1). By recycling senescent erythrocytes, macrophages in the liver and the spleen normally
supply most of the extracellular iron. During infection and
inflammation, macrophages retain iron, restricting its delivery to plasma and to erythrocyte precursors (Figure12.2).
Iron restriction oferythropoiesis
Iron restriction of erythrocyte production is an active regulatory process that slows down erythropoiesis when iron concentrations in plasma are low, effectively reallocating scarce
transferrin- bound iron for non- erythroid cellular processes.
In anemia of inflammation, some of the iron not used for
erythropoiesis is redirected to the production of leukocytes
for host defense. Although hypoferremia develops within
hours of the onset of infection or inflammation, the effect of
decreased iron and decreased hemoglobin synthesis on circulating erythrocytes is not immediately reflected in average
erythrocyte hemoglobin content or size. This is because the
iron restriction affects only erythrocyte precursors engaged
in hemoglobin synthesis and not mature erythrocytes. New
erythrocytes normally replace less than 1% of the circulating
erythrocytes per day, so the average erythrocyte indices
(mean corpuscular hemoglobin concentration, mean corpuscular volume) change slowly. However, some newer
blood analyzers, which can measure the hemoglobin content
of reticulocytes, detect the effect of iron restriction as a
decrease in reticulocyte hemoglobin before there is a significant change in total hemoglobin. Iron restriction in anemia
of inflammation is also detected as an increase in zinc protoporphyrin. Normally, when iron is sufficient during an intermediate step in the synthesis of heme, iron becomes
incorporated into protoporphyrin IX. In iron deficiency, zinc
partially replaces iron and the amount of zinc incorporated
into protoporphyrin IX is increased. In anemia of inflammation, zinc protoporphyrin is also increased, indicating that
insufficient iron is reaching the sites of heme synthesis in
developing erythrocytes. Over the course of several weeks,
iron restriction results in anemia that can eventually become
microcytic and hypochromic and resemble iron-
deficiency
本书版权归John Wiley & Sons Inc.所有
Ferroportin
Inammation
https://t.me/med1917
RBC
Ferroportin
RBC
Increased
hepcidin
RBC
Anemia ofchronic disease 171
Hepcidin
RBC
Ferroportin
Ferroportin
Hepcidin
Figure12.1 Hepcidin–ferroportin interaction causes iron sequestration in macrophages. (Left) Macrophages in the spleen and liver ingest
senescent erythrocytes and extract their iron. When hepcidin is low, ferroportin molecules on macrophage cell membranes rapidly export the
recycled iron (gray tint). (Right) During inflammation, hepcidin synthesis is increased; hepcidin binds to macrophage ferroportin, occludes it, and
induces its internalization and degradation. Export of iron from macrophages slows, and iron remains in macrophage cytoplasm bound to ferritin.
Macrophage
RBC
Ferroportin
RBC
Macrophage
Hepcidin
Hepcidin
Hepcidin
Spleen
↓Fpn
↓Fe
Plasma
↓Fe-Tf
↓Fe-Tf
Liver
↑hepcidin
↑hepcidin
↑hepcidin
↓Fpn
↓Fe
↓Fpn
↓Fe
Hepcidin
Figure12.2 Iron restriction in anemia of inflammation. Under the influence of increased hepcidin concentrations, the release of stored and
recycled iron from splenic and hepatic macrophages and hepatocytes is decreased, as is the absorption of dietary iron in the duodenum.
Continued iron utilization depletes plasma iron, causing hypoferremia and limiting iron delivery to erythropoietic tissue. Fpn, ferroportin.
本书版权归John Wiley & Sons Inc.所有
↓Erythropoiesis
Duodenum
172 Molecular Hematology
https://t.me/med1917
anemia. The development of anemia of inflammation is
accelerated by other effects of inflammation or the underlying disease that may act to shorten erythrocyte lifespan or
cause blood loss.
Effects ofinflammation oniron absorption andrelease
fromstores
Inflammation- induced hepcidin also decreases the absorption of dietary iron by acting on ferroportin displayed on the
basolateral membranes of enterocytes. Decreased iron
absorption usually does not contribute much to the development of anemia because iron stores (when normal) are generally sufficient to supply erythropoiesis for many months.
However, the inflammatory blockade of iron absorption may
contribute to anemia in situations where iron demand is high
and inflammation is long- lasting, as is the case in growing
children with inflammatory bowel diseases or juvenile rheumatological disorders. Hepcidin would also be expected to
inhibit the release of iron from hepatocyte stores, but the
contribution of this effect to anemia of inflammation has not
yet been established.
Cytokines involved inanemia ofinflammation
The contribution of specific cytokines to hypoferremia and
anemia of inflammation has been difficult to delineate,
mainly because cytokines interact in complex networks regulating each other’s synthesis. In humans, depending on the
disease, therapies targeting IL- 1, IL- 6, and tumor necrosis
factor (TNF)- α have all been shown to improve anemia of
inflammation along with other inflammatory manifestations. The association of IL- 6with anemia of inflammation
appears to be the strongest. In both humans and mouse
models, IL- 6 induces hepcidin synthesis within hours by a
JAK- STAT3 (Janus kinase- signal transducer and activator of
transcription 3)- mediated transcriptional mechanism, causing hypoferremia.
Cytokines also have direct effects on erythropoiesis.
Studies in erythropoietic culture systems have demonstrated
that TNF-
α, IL- 1, interferon (IFN)- β, and IFN- γ can inter-
fere with erythropoietin stimulation of erythroid progenitors. This effect is seen even in mice engineered to lack
hepcidin, where treatment with potent inflammatory stimuli
does not cause hypoferremia, but anemia still develops,
albeit in a substantially milder form than in the presence of
hepcidin and hypoferremia.
Inflammation anderythropoietin resistance
The normal response to anemia is an increase in erythropoietin production and a subsequent compensatory increase in
erythropoiesis. It has been suggested that for the same severity of anemia, erythropoietin production in anemia of
inflammation is lower than it would be in other types of anemia. Indeed, in some studies of patients with anemia associated with rheumatoid arthritis or cancer, erythropoietin
levels were not as high as in iron- deficiency anemia, but
other studies have not observed a significant difference in
erythropoietin concentrations between iron deficiency and
anemia of inflammation. Erythropoietin suppression by
cytokines or lipopolysaccharide has been seen in some animal models of sepsis as well as in erythropoietin- producing
cell lines. However, such suppression of erythropoietin production is not a major pathogenic mechanism of anemia of
inflammation. If it were, the administration of relatively
small amounts of erythropoietin should be sufficient to
reverse the anemia of inflammation. Clinical experience and
studies in animal models suggest the opposite: severe inflammation decreases the effectiveness of erythropoietin, a common clinical situation described as erythropoietin resistance.
Both anemia and erythropoietin resistance have been seen in
mice with mild transgenic hepcidin overexpression as well as
in mice and humans with TMPRSS6 (transmembrane serine
protease 6, also called matriptase2 or MT2) mutations that
cause moderate overexpression of hepcidin, supporting the
importance of the hepcidin–ferroportin axis and inflammatory iron restriction in the pathogenesis of anemia of inflammation as well as in erythropoietin resistance.
Effects ofinflammation onerythrocyte lifespan
In early studies, a small decrease in erythrocyte lifespan was
noted in some animal models of inflammation, and it was
suggested that inflammation activates reticuloendothelial
macrophages to increase the removal of damaged or senescent erythrocytes. Other potential disease- specific mechanisms that could contribute to the decreased lifespan include
the deposition of opsonic antibodies on erythrocytes and
mechanical damage to erythrocytes from microvascular
fibrin strands or injured endothelia. In most cases, the
effects on erythrocyte lifespan are relatively small and would
be compensated by a minor increase in erythropoiesis;
however, this compensation does not take place in anemia
of inflammation.
Principles oftreatment
Most often, the presenting symptoms of anemia of inflammation, fatigue, and exercise intolerance are difficult to distinguish from those of the underlying disease, be it an
infection, inflammatory disease, or malignancy. Whenever
possible, the treatment should be aimed at the underlying
disease. Effective treatment of the underlying disease will
also lead to the resolution of anemia. Unfortunately, this is
not always feasible.
本书版权归John Wiley & Sons Inc.所有
Соседние файлы в папке Библиотека им академика М.И. Перельмана