Question

In certain portions of the Jewish population, there is a genetic disease called Tay Sachs disease, which is fatal to infants within the first five years of life. This disease is caused by a recessive allele of a single gene. Why does this disease persist, even though it is invariably fatal long before the afflicted individual reaches reproductive age? (In other words, why doesn’t the allele for Tay Sachs disease simply disappear?)

Answer 1

Because Tay Sachs is a recessive gene.

Step-by-step explanation:

It takes two donors both with a recessive gene for the gene to express itself. In this case, two people both with the recessive Tay Sachs disease would have to have children. But when people marry who have the trait, the recessive gene, the recessive can be passed on through to the next generation and so on.