Tay-Sachs disease is an autosomal recessive neurological disorder that is fatal in infancy. Despite its invariably lethal effect, Tay-Sachs disease occurs at very high frequency in some Central and Eastern European (Ashkenazi) Jewish populations. In certain Ashkenazi populations, 1 in 650 infants has Tay-Sachs disease. Population biologists believe the high frequency is a consequence of genetic bottlenecks caused by pogroms (genocide) that have reduced the population multiple times in the last several hundred years.
Part A
In the population described, what is the frequency of the recessive allele that produces Tay-Sachs disease?
Part B
Assuming mating occurs at random in this population, what is the probability a couple are both carriers of Tay-Sachs disease?