Ch 18 Plus

Question 1

Which mucopolysacaridosis are most likely to produce severe corneal opacification?

Answer 1

MPS I-H (Hurler’s Sd)
MPS VI (Maroteaux-Lamy Sd)

Question 2

Which enzime is involved in the pathogenesis of Hurler’s Sd?

Answer 2

Hurler’s syndrome (MPS I-H) or gargoylism is caused by a
deficiency of alfa-l-iduronidase and the gene involved with
this error is mapped to 4p16.3

Question 3

Difference in the corneal opacity produces by Hurler and Hunter Syndromes?

Answer 3

Hurler’s opacity is very marked, while Hunter’s is Mild or even sub clinical

Question 4

Which enzyme is responsible for MPS VI?

Answer 4

Maroteaux–Lamy syndrome (types VIA and VIB) is caused
by arylsulfatase B deficiency and the causative gene was
mapped to 5q13

Question 5

Which enzime is responsible for MPS I-S (Scheie)?

Answer 5

Scheie’s syndrome (MPS I-S) is caused by a mutation in

the gene encoding alfa-l-iduronidase, mapped to 4p16.3

Question 6

Name the 4 MPS that can produce mild forms of corneal opacification after the first decade of life.

Answer 6

MPS-IS: Scheie (although rarely congenital, this one can present earlier)
II: Hunter
III: Sanfilipo
IV: Morquio

Question 7

Which enzime responsible for Morquio’s Syndrome?

Answer 7

Morquio’s syndrome (MPS types IVA and IVB) has two
subtypes, A and B, which result from a deficiency of galac-
tosamine-6-sulfate sulfatase and beta-galactosidase, respec-
tively

Question 8

Which enzime is responsible for Hunter’s Sd?

Answer 8

Hunter’s syndrome (MPS II) is inherited as an X-linked
recessive trait (gene mapped to Xq28) resulting in a defi-
ciency of iduronate sulfatase and does not present as a con-
genital corneal opacity.

Question 9

Is PK curative for corneal opacitication in MPS-IH, IS and VI?

Answer 9

It is a treatment option but:

1. MPS may continue to deposit in the graft.
2. Most be assessed for retinopathy, glaucoma and optic neuropathy, since this are concomitant and may be the primary source for vision loss.

Question 10

Can bone marrow transplant help to treat ocular manifestations of Metabolic diseases?

Answer 10

Yes, bone marrow transplant stimulate synthesis of the affected enzime and can halt the progression of opthalmic pathology, and even clear a mildly opacified cornea,