Hardy-Weinberg Equilibrium Study of Some Morphogenetic Traits in a Nigerian Population

Abstract

Background: The Hardy-Weinberg (HW) equilibrium studies the distribution of allelic and genotypic frequencies within a population. It provides a mathematical benchmark for a population that is evolving and not evolving. Aim: This study investigated six morphogenetic traits among families in a Nigerian population using the Hardy-Weinberg principle with the aim of evaluating if the population was in HW equilibrium. Methodology: A total of 45 families comprising a father, mother and at least one offspring were conveniently sampled in Ogbe- Ijoh district in Delta State, Nigeria. Earlobe attachment, Hand clasping, Hitchhiker’s thumb, Leg folding, Morton's toe and Widow's peak were studied for their allelic and genotypic frequencies. The Chi-square test was used to analyse the association between these traits and sex, and conformance to the Mendelian inheritance pattern was evaluated with a Mendelian Chi-square. The Hardy-Weinberg equilibrium compared the allelic frequencies of parents with those of offspring. Results: Males had higher frequencies for attached earlobes, Morton’s toe and widow's peak (35.1, 51.9, 49.4%), while the females showed a predominance for hitchhiker's thumb, right hand clasping and leg folding (50,72.4,70.7%). There was no association between the traits and gender (p>0.05). From the Mendelian Chi-square, free earlobe, right-hand clasping, right leg folding, Morton's toe (SBt), the recessive phenotype of hitchhiker's thumb as well as widow's peak were the dominant traits in the studied population (X2 < 3.841 ). The H-W equation revealed a deviation of the offspring’s genotype from those of the parents for earlobe, hand clasping, leg folding, Morton’s toe and widow's peak (1:1:2 [1:1; 4]; 2: 1: 3 [1:1:2]; 3:1:3 [1:1:2]; 5: 1: 4 [6:1:5}; 5:1:4 [7: 1:5]). However, parental and offspring alleles were identical for hitchhiker's thumb (5:1:5 [5:1: 5]). The homozygotes for both parents and offspring outnumbered the heterozygotes for all traits (295: 245; 156: 119). Conclusion: The study showed that only the hitchhiker's thumb was in HW equilibrium, suggesting that evolution may not occur at that locus. KEYWORDS: Hardy-Weinberg equilibrium, Mendel, Traits, Nigeria, Population.