Evaluation of nose shape as a Mendelian-inherited trait in the determination of parentage among Nigerians in Port Harcourt

Abstract

Background: Nose shape might be environmentally influenced; however, there are evidences of it being inherited in simple Mendelian dominant-recessive patterns. In such instance, a nose can be broad or narrow with respect to its wideness in comparison to the intercanthal bridge. Therefore, this study was aimed at determining the inheritance pattern of nose shape in the bid to ascertain its usability in parentage determination. Methods: Three hundred and thirty-seven subjects from 101 families comprising 202 parents and 135 offspring were recruited for this study. The families were randomly selected from within Port Harcourt by a multistage sampling technique. Their nose shape were observed physically in the father, mother, and at least a child in each family and documented. The offspring traits were tabularized in patterns of parental combinations (when both parents' nose are broad, both parents' nose are narrow, and a combination of broad and narrow). SPSS IBM (r) version 20 was used to analyze the data. Descriptive statistics and test for association between sex and nose shape was carried out by Chi-square analysis and the conformance to Mendelian inheritance pattern was analyzed using Mendelian Chi-square gene distribution model. Results: Broad nose shape was more frequent with 298 (88.4%) when compared to narrow nose shape (11.6%). About 46.9% of males had broad nose against 41.5% for females. However, this distribution was not observed to follow any sexual preference (χ2 = 0.141, P > 0.932). The observed and expected outcome were tested for significance on the assumption that offspring outcome conforms to Mendelian simple dominant-recessive monohybrid cross; conformance was observed. Conclusion: The distribution of nose shape was observed to be genetically determined and follows Mendelian single gene dominant-recessive pattern with the allele for narrow nose dominant over the allele for broad nose. This result can be used for preliminary screening in parentage dispute. It can also be useful in forensic and genetic studies.