An unusual genotype in an Ashkenazi Jewish patient with Tay-Sachs disease

✍ Scribed by Shirah Shore; Jerzy Tomczak; Eugene E. Grebner; Rachel Myerowitz

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 438 KB
• Volume: 1
• Category: Article
• ISSN: 1059-7794
• DOI: 10.1002/humu.1380010606

✦ Synopsis

Communicated by Robert J. Desnick

The Ashkenazi Jewish population is enriched for carriers of a fatal form of Tay-Sachs disease, a recessive inherited disorder caused by mutations in the a-chain of the lysosomal enzyme P-hexosaminidase A. Approximately 20% of the Ashkenazi carriers harbor a splice junction defect while about 78% bear a 4 base pair (bp) insertion. However, the Ashkenazi Jewish patient used in the original description of the 4 bp insertion carried this lesion in only 1 allele and was negative for the splice junction mutation. We cloned the insertion negative allele and by sequence analysis of the exons found a point mutation in exon 11 that results in substitution of Trp392 with a premature termination codon. Nine Ashkenazi Jewish carriers that tested negative for the major and minor mutations as well as for a lesion causing an adult form of Tay-Sachs disease did not carry the base change defect, suggesting that it may be a recent and/or rare mutation. This finding also indicates that screening the Ashkenazi population solely by recombinant DNA methods for the splice junction, 4 bp insertion, and adult mutations may result in occasional false negatives.