Thursday, January 1, 2015

A Case of Child with Mucopolysaccharidosis - Hunter Syndrome


A 6 year old patient was found to have course facial features and short stature. Parents have noticed a developmental stasis since 4-5 years of age. The weight was normal. There was no any chronic illness, any significant birth and postnatal history contributing to the condition. There was no history of short stature or pubertal delay in the family members. Nutritional status was good.

On examination- The child had coarse facial features, with low anterior hair line and prominent angles of face. Looked stunted and no skin changes,no thyroid enlargement. Abdominal examination revealed Hepatosplenomegaly. Cornea was clear but sclera looked muddy.
There were no major limb deformity or bending. No pallor.

Anthropometric measurements-
Ht- less than 3 rd centile
Wt/Ht- Normal
Upper segment: Lower segment ration was - 1:1 at 6 years
Arm span was normal.

We suspected Mucopolysaccharidosis. 
Differentials were- Hypothyroidism, Mucolipidosis, or other Metabolic storage disorders. As TSH, T4 were normal hypothyroidism was ruled out. Other conditions were less likely from clinical information and findings.

We sent Xray of Hand and Spine-

Xray showed- Increased trabeculation with Bullet shaped phalanges. Bone trabeculation is coarse and the cortices are thin.
Spine - mild changes with Beaking of vertebrae.





Review : Mucopolysaccharidosis-

Mucopolysaccharidoses are hereditary, progressive diseases caused by mutations of genes coding for lysosomal enzymes needed to degrade glycosaminoglycans. Products of GAG, Keratan sulphate, Dermatan Sulphate , chondroitin sulphate  accumulates in body and cause various manifestations.

As a general rule, the impaired degradation of heparan sulfate is more closely associated with mental deficiency and the impaired degradation of dermatan sulfate, chondroitin sulfates, and keratan sulfate with mesenchymal abnormalities

There are 7 variants. Recognition of type depends on clinical manifestations, severity and corneal involvement.

I- Hurler Syndrome
II- Hunter Syndrome
III- San Filippo
IV- Morquio
VI-Maroteaux-Lamy
VII- Sly
IX- Hyaluronidase deficiency

Among these all are inherited via Autosomal recessive inheritance except Hunter Syndrome which is an X-linked disorder.


Here is a summary of involvement of organs in different MPS variants-
Hepatosplenomegaly, Coarse facial features, Short stature- disproportionate with Bony changes and Mental deficiency are main features. Corneal clouding in seen in most variants as disease progresses except in Hunter and San filippo syndromes.

In this Child:
We found Short stature, coarse facial features, Dysostosis multiplex, Clear Cornea and visceromeglay with minimal mental deficiency. Likely to be Hunter Syndrome.

This is how a patient with Hunter Syndrome looks like-



Investigations-
Routine CBC, LFT, RFT and urine were normal in the child. On evaluation eye was normal, no cherry red spot on retina.

Urinary GAG quantification was too expensive and could not be done in this patient, likewise Genetic analysis and carrier mapping was not feasible.

Treatment Options-
Available options today are-

1. Hematopoetic Stem cell transplant 
which can be curative. If done before 2 yrs can prevent progression of mental deficiency but this modality does not treat bone and eye problems.
 Transplantation prevents neurocognitive degeneration but does not correct existent cerebral damage. Hence, the main target group are young children with severe MPS I, anticipated neurodegeneration, who undergo transplantation before 24 mo of age and have a baseline mental development index >70.- Nelson textbook of Pediatrics 19th Edition.

2.Replaement Therapy- recombinant enzymes is approved for patients with MPS I, MPS II, and MPS VI.

3.Management of Complications like Hydrocephalus, Orthopedic and vision issues etc.


As we could not objectively prove our Diagnosis, if you have a different diagnosi or opinion for this case, you are free to comment. 

2 comments:

  1. There is an error in this article. It notes that HSCT can prevent mental deficiency which is only true in limited cases of MPS. The case studies appear to show that HSCT only prevents mental deficiency (or realistically, only halts mental decline once full engraftment is achieved) in MPS I-H. Case studies appear to show that that is NOT the case in MPS II or MPS III, i.e., while HSCT could possibly slow down the mental decline, it does not appear to prevent the cognitive deficiencies and eventual decline caused by those forms of MPS.

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    1. Thank you Melissa for you valuable comment. I have made correction and quoted my source textbook. You are right in this case, it has been seen to be useful in Hurler Syndrome .

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