Albinism, an autosomal recessive trait characterized by an absence of skin pigmentation, is found in 1 in 4000 people in populations at equilibrium. Brachydactyly, an autosomal dominant trait producing shortened fingers and toes, is found in 1 in 6000 people in populations at equilibrium. For each of these traits, calculate the frequency of the dominant allele at the locus

Key Concepts

Autosomal Recessive and Dominant Traits

Autosomal recessive traits require two copies of the recessive allele for expression, while autosomal dominant traits require only one copy of the dominant allele. In the case of albinism, individuals must inherit two recessive alleles (aa) to exhibit the trait, whereas for brachydactyly, inheriting just one dominant allele (Bb or BB) is sufficient for expression.

Hardy-Weinberg Equilibrium

The Hardy-Weinberg principle provides a mathematical framework for understanding allele frequencies in a population at equilibrium. It states that allele and genotype frequencies will remain constant from generation to generation in the absence of evolutionary influences. This principle allows for the calculation of allele frequencies based on observed genotype frequencies.

Allele Frequency Calculation

To calculate the frequency of alleles in a population, the Hardy-Weinberg equation (p^2 + 2pq + q^2 = 1) is used, where p represents the frequency of the dominant allele and q represents the frequency of the recessive allele. For albinism, the frequency of the recessive phenotype (q^2) can be used to find q, and subsequently p, while for brachydactyly, the frequency of the dominant phenotype can be used to find p directly.