Red–green color blindness is a relatively common condition found in about 8% of males in the general population. From this, population, biologists estimate that 8% is the frequency of X chromosomes carrying a mutation of the gene encoding red and green color vision. Based on this frequency, determine the approximate frequency with which you would expect females to have red–green color blindness. Explain your reasoning.

Key Concepts

X-Linked Inheritance

Red-green color blindness is an X-linked recessive trait, meaning the gene responsible for this condition is located on the X chromosome. Males, having one X and one Y chromosome, express the trait if their single X carries the mutation. In contrast, females have two X chromosomes, so they must inherit two copies of the mutated gene to express the condition.

Hardy-Weinberg Principle

The Hardy-Weinberg principle provides a mathematical framework for understanding allele frequencies in a population at equilibrium. It allows biologists to estimate the frequency of genotypes based on known allele frequencies. In this case, knowing that 8% of males are affected helps estimate the carrier frequency in females, as the principle can be applied to predict the expected prevalence of the trait in both sexes.

Carrier Frequency in Females

To determine the frequency of red-green color blindness in females, we need to consider that females can be carriers of the mutation without expressing the trait. If 8% of males are affected, the frequency of the X chromosome carrying the mutation is 0.08. Using the Hardy-Weinberg equation, we can calculate the expected frequency of affected females and carriers, leading to an understanding of how many females might express or carry the trait.