Home / study / science / biology / biology questions and answers / in certain portions of the jewish population, there is a genetic disease called tay sachs disease, question: in certain portions of the jewish population, there is a genetic disease called tay sachs 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?