GM2-ganglioside metabolism in hexosaminidase A deficiency states: determination in situ using labeled GM2 added to fibroblast cultures
To clarify the relationship between hexosaminidase A (HEX A) activity and GM2-ganglioside hydrolysis in atypical clinical situations of HEX A deficiency, we have developed a simple method to assess GM2-ganglioside metabolism in cultured fibroblasts utilizing GM2 labeled with tritium in the sphingosine portion of the molecule. The radioactive lipid is added to the media of cultured skin fibroblasts, and after 10 days the cells are thoroughly washed, then harvested, and their lipid composition analyzed by HPLC. The degree of hydrolysis of the ingested GM2 is determined by comparing the amount of radioactive counts recovered in undegraded substrate with total cellular radioactivity. A deficiency in GM2-ganglioside hydrolysis was demonstrated in seven HEX A-deficient adults with neurological signs and in two healthy-appearing adolescents with older affected siblings. In each case, an analysis of endogenous monosialoganglioside composition revealed an increase in GM2-ganglioside, confirming the presence of a block in the metabolism of GM2. No defect in GM2-catabolism was found in four other healthy individuals with HEX A deficiency. This method of assay is especially helpful in the evaluation of atypical cases of HEX A deficiency for the definitive diagnosis of GM2-gangliosidosis.
- Research Organization:
- Eunice Kennedy Shriver Center for Mental Retardation, Inc., Waltham, MA
- OSTI ID:
- 5881568
- Journal Information:
- Am. J. Hum. Genet.; (United States), Vol. 6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GANGLIOSIDES
METABOLISM
BIOCHEMICAL REACTION KINETICS
ENZYME ACTIVITY
FIBROBLASTS
HYDROLYSIS
IN VITRO
LEUKOCYTES
SKIN
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ANIMAL CELLS
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY
BODY FLUIDS
CARBOHYDRATES
CHEMICAL REACTIONS
CONNECTIVE TISSUE CELLS
DECOMPOSITION
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIPIDS
LYSIS
MATERIALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
REACTION KINETICS
SACCHARIDES
SOLVOLYSIS
SOMATIC CELLS
550501* - Metabolism- Tracer Techniques