Consider the following pedigree of a rare autosomal trait Be

Consider the following pedigree of a rare autosomal trait. Be sure to take into account the inbreeding convention. After divorce, individual \"A\" decides to marry at random outside the pedigree. If the population allele frequency of the rare autosomaltrait is 0.012, what are the chances of having an affected child for his first born of his second marriage?

Solution

The pedigree shows the recessive autosomal trait.It means in the first generation the female(AA⁰)and male (AA⁰)both are heterozygous for the trait.when they get married there is possibilty that 25% child is affected, 50% are heterozygous(carrier) and 25% are normal.

Now A marries with a individual other than pedigree there are two possibilities:(1) as the A is carrier (AA⁰) If the female is normal (AA) than there will be no children born with the recessive trait all children will be (AA⁰). (2) But if the female is heterozygous (AA⁰) then 25% children will be affected, 50 %will be again heterozygous and 25% will be normal.