Becker's World of the Cell 9th Edition by Lewis Kleinsmith, Jeff Hardin, Gregory Paul Bertoni

Exercise 4

Tay-Sachs Screening. In a certain community, a mutant allele for Tay-Sachs disease (the gene encoding the enzyme hexosaminidase A)exists at a high frequency. This mutation removes a Hin dIII restriction site (H)in the gene. A probe is available for this region, as shown in Figure 21-33a. Two couples in this community are expecting children. Each couple has a prenatal DNA test to determine if their child will have Tay-Sachs. The results of a Southern

blot using Hin dII digested DNA probed for the region are shown in Figure 21-33b. What advice would you give to each couple in terms of preparing for a child with Tay-Sachs