SANDHOFF DISEASE

Gangliosidosis GM2 Type II; Gangliosidosis Beta Hexosaminidase B Deficiency; Hexosaminidases A and B Deficiency; Sandhoff-Jatzkewitz Disease

Sandhoff Disease is a rare, genetic, lipid storage disorder resulting in the progressive deterioration of the central nervous system. Sandhoff Disease is caused by a mutation (defect) in the HEXB gene. This defect causes a deficiency of the enzyme beta-hexosaminidase, which results in the accumulation of certain fats (lipids) in the brain and other organs of the body.

Infantile form: Onset of the disorder usually occurs at 6 months of age. Infants with Sandhoff Disease typically appear normal until the age of 3 to 6 months, when development slows and muscles used for movement weaken.

Diagnostic testing: Positive gene testing confirms the diagnosis of this disease. A simple blood enzyme analysis test that measures HEXB activity can identify individuals and carriers of Sandhoff Disease.

Physical findings: Sandhoff Disease symptoms may include:

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  Motor weakness;

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  Startle reaction to sound;

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  Early blindness;

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  Progressive mental and motor deterioration;

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  Macrocephaly (an abnormally enlarged head);

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  Cherry-red spots in the eyes;

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  Seizures;

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  Myoclonus (shock-like contractions of a muscle);

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  Frequent respiratory infections;

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  Doll-like facial appearance; and

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  An enlarged liver and spleen.

ICD-9: 330.1

ICD-10: E75.01

Onset occurs by 6 months of age. The prognosis for individuals with Sandhoff Disease is poor. In the Infantile form, affected children usually do not survive past the age of 3 and death is generally caused by respiratory infections.

There is no specific treatment for Sandhoff Disease. Supportive treatment includes proper nutrition and hydration, and keeping the airway open. Anticonvulsants may initially control seizures. In other ongoing studies, a small number of children have received an experimental treatment using transplants of stem cells from umbilical cord blood. Although these limited trials have not yet produced a treatment or cure, scientists continue to study these and other investigational approaches.

Suggested MER for Evaluation:

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  Genetic testing for a mutation in the HEXB gene, and a clinical description of the physical and developmental features; and

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  If definitive genetic testing is not available, the results of other laboratory studies such as enzyme assays, molecular cell analysis, and tissue biopsy can be substituted.

Suggested Listings for Evaluation:

REMARKS

Catastrophic congenital abnormality or disease.