1) A rare human disease – Snyder Robinson Syndrome – is due to a genetic defect in enzyme called SMS. In a certain, isolated population, a heterozygote child carrying one mutant (defective) allele and one wild-type allele of SMS gene has 5% less chance of surviving into an reproductive adult compared to a homozygous child with two wild-type alleles. A homozygote child with two mutant alleles suffers 28% decline in survival relative to a wild-type homozygote. (Once becoming adults, individuals with three genotypes all leave the same number of offspring, on average.) A deleterious mutation that destroys the normal function of SMS occurs during meiosis with probability 10-4. (10 points total; 5 pts. ea).
a. What is the expected long-term equilibrium frequency of the defective SMS allele in this population?
b. Given the answer to the above question, what is the expected number of children who are homozygous for defective alleles if there are 10 million children in this population?