| Autor: |
Cao Z; Department of Biochemistry and Molecular Biology, University of Manitoba, Winnipeg, Canada., Natowicz MR, Kaback MM, Lim-Steele JS, Prence EM, Brown D, Chabot T, Triggs-Raine BL |
| Jazyk: |
angličtina |
| Zdroj: |
American journal of human genetics [Am J Hum Genet] 1993 Dec; Vol. 53 (6), pp. 1198-205. |
| Abstrakt: |
Deficient activity of beta-hexosaminidase A (Hex A), resulting from mutations in the HEXA gene, typically causes Tay-Sachs disease. However, healthy individuals lacking Hex A activity against synthetic substrates (i.e., individuals who are pseudodeficient) have been described. Recently, an apparently benign C739-to-T (Arg247Trp) mutation was found among individuals with Hex A levels indistinguishable from those of carriers of Tay-Sachs disease. This allele, when in compound heterozygosity with a second "disease-causing" allele, results in Hex A pseudodeficiency. We examined the HEXA gene of a healthy 42-year-old who was Hex A deficient but did not have the C739-to-T mutation. The HEXA exons were PCR amplified, and the products were analyzed for mutations by using restriction-enzyme digestion or single-strand gel electrophoresis. A G805-to-A (Gly269Ser) mutation associated with adult-onset GM2 gangliosidosis was found on one chromosome. A new mutation, C745-to-T (Arg249Trp), was identified on the second chromosome. This mutation was detected in an additional 4/63 (6%) non-Jewish and 0/218 Ashkenazi Jewish enzyme-defined carriers. Although the Arg249Trp change may result in a late-onset form of GM2 gangliosidosis, any phenotype must be very mild. This new mutation and the benign C739-to-T mutation together account for approximately 38% of non-Jewish enzyme-defined carriers. Because carriers of the C739-to-T and C745-to-T mutations cannot be differentiated from carriers of disease-causing alleles by using the classical biochemical screening approaches, DNA-based analyses for these mutations should be offered for non-Jewish enzyme-defined heterozygotes, before definitive counseling is provided. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
|
