Question

Hemochromatosis is an autosomal recessive disease that is relatively common in the population (1 in 500). The disease can be treated successfully by periodic removal of blood (serial phlebotomy) but failure to recognize it can lead to a number of serious conditions. Population screening for carriers is being considered. What is the expected carrier frequency in the population?

(A) 0.10%
(B) 0.20%
(C) 2.25%
(D) 8.5%
(E) 15%

Answer 1

The expected carrier frequency of autosomal recessive hemochromatosis in the population is calculated using the Hardy-Weinberg principle. With a disease prevalence of 1 in 500, the carrier frequency is found to be approximately 8.5%.

Step-by-step explanation:

Hemochromatosis is an autosomal recessive disease and is considered relatively common in the population, with a prevalence of 1 in 500 individuals. To determine the expected carrier frequency in the population, we can use the Hardy-Weinberg principle which states that p² + 2pq + q² = 1. Here, p² represents the frequency of homozygous dominant individuals (normal phenotype), 2pq represents the frequency of heterozygous individuals (carriers), and q² represents the frequency of homozygous recessive individuals (affected by the disease).

Since we know that the disease frequency (q²) is 1/500, we can calculate q as the square root of 1/500, which is approximately 0.0447. This means that p (the frequency of the normal allele) is 1 - q, which is approximately 0.9553. The carrier frequency (2pq) would then be 2 * 0.9553 * 0.0447, which gives us an approximate carrier frequency of 0.0853, or 8.5% in the population.