# 5.S: Pedigrees and Populations (Summary)

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• Pedigree analysis can be used to determine the mode of inheritance of specific traits such as diseases. Loci can be X- or Y-linked or autosomal in location and alleles either dominant or recessive with respect to wild type.
• If the mode of inheritance is known, a pedigree can be used to calculate the probability of inheritance of a particular genotype by an individual.
• The frequencies of all alleles and genotypes remain unchanged through successive generations of a population in Hardy-Weinberg equilibrium.
• Populations in true Hardy-Weinberg equilibrium have random mating, and no genetic drift, no migration, no mutation, and no selection with respect to the gene of interest.
• The Hardy-Weinberg formula can be used to estimate allele and genotype frequencies given only limited information about a population.

## Key Terms

 Pedigree charts mode of inheritance genetic counseling incomplete penetrance variable expressivity proband affected carrier autosomal dominant autosomal recessive X-linked dominant X-linked recessive Y-linked inheritance Y-linked mitochondrial inheritance (mtDNA) sporadic product rule sum rule population p+q=1 Hardy-Weinberg formula p2 + 2pq + q2=1 Hardy-Weinberg equilibrium assortative mating random mating migration genetic drift

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