Phenylketonuria is a severe form of mental retardation caus

. Phenylketonuria is a severe form of mental retardation caused by a recessive allele. The condition affects about 1 in 25,000 newborn babies. In a population of 50,000 people, how many are expected to be carriers (heterozygous) for this disease?

Solution

Condition affects 1 in 25000 babies.. That\'s a recessive trait. Therefore q = (1/25000)^-1/2 = 0.0063 so , p= (1- 0.0063)= 0.9936 . So 2pq=0.0125( heterozygote frequency) so in total population of 50,000 people total gene pool should be

(50000x2)= 100000, so no of heterozygous individuals are (100000x0.0125)=1251 (approximately) . Here p= dominant gene frequency and q= recessive gene frequency and the some is done with the help of Hardy-Weinberg equation where(p+q)=1