Ocular and electrophysiological findings in a patient with Sly syndrome

ABSTRACT

Background: Sly syndrome (Mucopolysaccharidosis Type VII) is an autosomal recessive metabolic storage disorder due to mutations in the GUSB gene encoding the enzyme beta-glucuronidase. Deficiency of this lysosomal enzyme impairs the body’s ability to break down the glycosaminoglycans – dermatan, heparan and chondroitin sulphate. Coarse facial features and macrocephaly are typically seen along with bony and skeletal abnormalities, including joint contractures and short stature. Widespread involvement occurs in many other tissues including cardiopulmonary, gastrointestinal, and neurological systems. In view of the rarity of Sly syndrome the ophthalmic features have not been well described.Materials and methods: Case report of a 16-year-old boy with Sly syndrome with serial OCT, ocular ultrasound, and electroretinogram (ERG).Results: Corneal clouding was present but there was no evidence of glaucoma or optic neuropathy. Despite no clinical evidence of retinopathy, electrophysiology showed reduced photopic and scotopic responses, particularly involving the b-wave which appears progressive. OCT showed normal foveal architecture and normal retinal nerve fiber thickness.Conclusion: Corneal clouding was noted in this patient and there is no evidence of glaucoma or optic neuropathy. Although retinopathy has not been previously described in Sly syndrome, the ERG changes in this patient suggest that retinopathy may be a feature of MPS VII.

KEYWORDS:

• Corneal clouding
• electrophysiology
• ocular ultrasound
• retinopathy
• Sly syndrome

Literature search

PubMed review of English language articles was conducted using the following terms: Sly syndrome, mucopolysaccaridosis type VII, beta glucuronidase enzyme deficiency AND ocular features, corneal clouding, glaucoma, retinopathy, optic neuropathy.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Funding

This work was supported by research grants from BioMarin Pharmaceutical Inc. and Genzyme Australasia Pty Ltd (now Sanofi).

Additional information

Funding

This work was supported by research grants from BioMarin Pharmaceutical Inc. and Genzyme Australasia Pty Ltd (now Sanofi).