GM1 gangliosidosis type I; GM1 gangliosidosis type II; beta-galactosidase-1 (GLB1) deficiency; GLB1 deficiency; Landing disease; type 1 GM1 gangliosidosis; type 2 GM1 gangliosidosis; Beta-galactosidosis; Classic infantile (type 1) GM1 gangliosidosis; Juvenile (type 2) GM1 gangliosidosis

GM1 gangliosidosis is a rare lysosomal storage disorder characterized biochemically by deficient beta-galactosidase activity and clinically by a wide range of variable neurovisceral, ophthalmological, and dysmorphic features.

Diagnostic testing: Diagnosis may be difficult due to the wide clinical spectrum of the disease. Diagnosis is confirmed by:

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  Biochemical assay of beta-galactosidase activity and/or by molecular genetic testing; and

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  A secondary combined defect of both GLB1 and neuraminidase (NEU1) has to be excluded.

Other diagnostic testing includes:

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  Peripheral blood smear (testing vacuolated lymphocytes);

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  Urine oligosaccharides; and

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  Bone marrow examination.

Physical findings: Physical findings for types 1 and 2 GM1 gangliodosis may include:

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  Facial coarsening;

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  Gingival hypertrophy (enlarged gums);

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  Cherry-red macula;

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  Cardiomyopathy (enlarged, weakened heart muscle);

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  Enlarged organs inside of the abdomen, including liver, spleen, stomach, kidneys, or pancreas (visceromegaly);

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  Abnormal development of bones (dysostosis);

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  Developmental regression;

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  Dementia;

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  Ataxia;

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  Seizures;

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  Difficulties with speech; and

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  Psychomotor delay.

ICD-9: 277.89

Infants with Type 1 GM1 gangliosidosis typically appear normal until around 6 months of age when their development slows and muscles used for movement weaken. Affected children typically do not live past 2 years of age.

Type 2 GM1 gangliosidosis consists of intermediate forms of the condition, also known as the late infantile and juvenile forms. Children with GM1 gangliosidosis type 2 have normal early development, but they begin to develop signs and symptoms of the condition around the age of 18 months (late infantile form) or 5 years (juvenile form). Infants with GM1 gangliosidosis type 2 experience developmental regression but usually do not have cherry-red spots, distinctive facial features, or enlarged organs. Type 2 usually progresses more slowly than type 1, but still causes a shortened life expectancy. Children with the late infantile form typically survive into mid-childhood, while those with the juvenile form may live into early adulthood.

Treatment for GM1 gangliosidosis is symptomatic and supportive. Substrate reduction therapy is a potential approach for clinical trials in late-onset forms. Prognosis depends on the type of GM1 gangliosidosis and is extremely poor in the severe infantile form.

Suggested MER for Evaluation:

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  Clinical history and examination that describes diagnostic features of the impairment;

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  Results of genetic testing confirming diagnosis of the impairment; and

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  Definitive results of other diagnostic testing.

Suggested Listings for Evaluation:

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