Hunter’s syndrome (MPS II)

Morquio’s syndrome

Idiopathic

(MPS IV A and B)

mucopolysaccharidoses

Morquio’s syndrome is an AR deficiency of

Congenital corneal opacification due to

N-acetylgalactosamine-6-sulfate sulfatase.

mucopolysaccharide accumulation

in the

This deficiency leads to the accumulation of

cornea has been reported in the absence of any

keratin sulfate. Corneal clouding can occur

systemic inborn error of metabolism.63 This is

with Morquio’s syndrome but this is often

a very rare cause of congenital corneal opacity

later in life. Accumulation of membrane-

and must be a diagnosis of exclusion.

bound inclusion bodies can also be found in

the conjunctiva and retina.59 Severe odontoid

Mucolipidosis

hypoplasia is common in this syndrome,

leading to cervical dislocation. Spondylo-

The mucolipidoses (MLs) are a group of

epiphyseal abnormalities and aortic regurgi-

storage diseases that have clinical features of

tation are also hallmarks of this syndrome.

both lipidoses and mucopolysaccharidoses.64

Patients with Morquio’s syndrome are of

Unlike in the mucopolysaccharidoses, the

normal intelligence.

urinary excretion of GAGs is normal. There are

four (I–IV) types of ML and all of them can

Maroteaux–Lamy

have corneal clouding. The congenital corneal

findings are most common in ML type IV,

syndrome (MPS VI

where it is a hallmark of the disease, and in

A and B)

type II (I-cell disease).

Corneal opacification in Maroteaux–Lamy

syndrome is a very common finding. The

Sialidosis (ML I)

primary enzyme deficiency is arylsulfatase B

and it is inherited in an AR manner. The lack of

ML I is caused by a deficiency in neuraminidase

arylsulfatase B leads to the accumulation

leading to an accumulation of sialyloligo-

of dermatan sulfate. As with many of the

saccharides. This disease exists in two major

other lysosomal storage diseases, skeletal

forms: infantile (I) and congenital (II) form.

abnormalities are common as is hepato-

Patients will often show hepatosplenomegaly,

splenomegaly. Coarse facies (mild), joint

mental retardation, skeletal abnormalities, and

stiffness, and heart disease are also common.

a cherry red spot on the retina.65 Corneal

Corneal opacities and clouding are very

clouding is seen, but is relatively uncommon.66

common in Maroteaux–Lamy syndrome at a

very young age.60 If the corneal opacification is

I-Cell disease (ML II)

severe corneal transplantation is necessary.

Glaucoma has also been reported in cases of

The enzymatic defect in ML II is in N-acetyl-

Maroteaux–Lamy syndrome.61

glucosaminyl-phosphotransferase. Affected

children with this condition typically have a short

Sly’s syndrome (MPS VII)

life expectancy. Clinical features include gingival

hyperplasia, hepatomegaly, delayed

motor

Sly’s syndrome is a rare AR syndrome due to a

development, coarse facial features, hirsutism,

defect in the enzyme β-glucuronidase. The

low-set ears, and corneal clouding. Almost half

enzyme deficiency leads to the accumulation of

of infants with I-Cell disease will have some level

dermatan sulfate. Patients with Sly’s syndrome

of congenital clouding of the cornea.67

have been reported to have corneal

opacification. Hepatosplenomegaly, skeletal