Skip to main content
Pearson+ LogoPearson+ Logo
Ch. 26 - Population and Evolutionary Genetics
Klug - Concepts of Genetics  12th Edition
Klug12th EditionConcepts of Genetics ISBN: 9780135564776Not the one you use?Change textbook
Chapter 26, Problem 6e

Consider rare disorders in a population caused by an autosomal recessive mutation. From the frequencies of the disorder in the population given, calculate the percentage of heterozygous carriers:
0.10

Verified step by step guidance
1
Identify the given value as the frequency of individuals affected by the autosomal recessive disorder, which corresponds to the homozygous recessive genotype frequency \(q^{2} = 0.10\).
Calculate the allele frequency of the recessive allele \(q\) by taking the square root of the affected frequency: \(q = \sqrt{q^{2}}\).
Determine the frequency of the dominant allele \(p\) using the relationship \(p + q = 1\), so \(p = 1 - q\).
Calculate the frequency of heterozygous carriers (the carriers) using the formula for heterozygotes in Hardy-Weinberg equilibrium: \$2pq$.
Convert the heterozygous carrier frequency \$2pq$ into a percentage by multiplying by 100 to express the final answer as a percentage of the population.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Autosomal Recessive Inheritance

Autosomal recessive disorders require two copies of a mutated gene for the phenotype to appear. Individuals with only one mutated allele are carriers and typically do not show symptoms. Understanding this inheritance pattern is essential to relate genotype frequencies to disease prevalence.
Recommended video:
Guided course
09:08
Autosomal Pedigrees

Hardy-Weinberg Equilibrium

The Hardy-Weinberg principle provides a mathematical framework to relate allele and genotype frequencies in a population under ideal conditions. It allows calculation of carrier frequencies from disease prevalence by using p² + 2pq + q² = 1, where q² represents affected individuals.
Recommended video:
Guided course
13:04
Hardy Weinberg

Calculating Carrier Frequency

Carrier frequency (heterozygotes) is calculated as 2pq, where p and q are allele frequencies. Given the disease frequency (q²), one can find q by taking the square root, then p = 1 - q, and finally compute 2pq to find the percentage of carriers in the population.
Recommended video:
Guided course
07:04
Calculating Heritability