Adult Sandhoff disease with 2 mutations in the HEXB gene presenting as brachial amyotrophic diplegia.

Abstract

Sandhoff disease is a rare autosomal recessive metabolic disorder of GM2 gangliosides. It is caused by a lack of functional N-acetyl-β-D-glucosaminidase A and B because of mutations in the HEXB gene. We describe a 55-year-old woman with adult Sandhoff disease presenting as brachial amyotrophic diplegia. The assay of total hexosaminidase involving A and B showed decreased level of these activities. Hex-A was 4.6 nmol·min·mL (normal: 7.0-20.0 nmol·min·mL) and Hex-B was 0.1 nmol·min·mL (normal: 1.0-10.0 nmol·min·mL), respectively. Analysis of HEXB gene demonstrated 2 point mutations that were located at the exon 5 (c.619A>G) and exon 11 (c.1250C>T). Compound heterozygosity of these 2 mutations may trigger the development of distinct adult Sandhoff disease phenotype. Sandhoff disease should be considered in the differential diagnosis of lower motor neuron disease, such as brachial amyotrophic diplegia, even if the age at onset is more than 50 years.

• Authors: Sa-Yoon Kang, Sook Keun Song, Jung Seok Lee, Jay Chol Choi, Ji-Hoon Kang
• Journal: Journal of clinical neuromuscular disease (J Clin Neuromuscul Dis) Vol. 15 Issue 2 Pg. 47-51 (Dec 2013) ISSN: 1537-1611 [Electronic] United States
• PMID: 24263030 (Publication Type: Case Reports, Journal Article)

Chemical References

• HEXB protein, human
• beta-Hexosaminidase beta Chain

Topics

• Diagnosis, Differential
• Female
• Humans
• Middle Aged
• Motor Neuron Disease (diagnosis, genetics)
• Mutation
• Phenotype
• Sandhoff Disease (diagnosis, genetics)
• beta-Hexosaminidase beta Chain (genetics)