Phenotypic association of seven observed traits of hand complex

Abstract

This paper provides an overview of the seven possible hand-related traits, with an idea to estimate the statistical phenotypic association between them. The traits observed in this study were: midphalangeal hair, Hitchhiker’s thumb, extensibility of proximal joint of thumb, digital index, nail shape, crooked fifth finger and hand clasping. The mentioned characteristics were observed in 7431 unrelated subjects, with approximately equal gender distribution. For each case, three groups were formed: total, male and female. The subjects were evenly distributed throughout Bosnia and Herzegovina’s various geographical regions, and they properly represent the country’s national and ethnic composition. The Chi-squared test was used to determine the statistical significance of the association between these traits, while Fisher’s exact test was utilized as an extra test to analyze the association between each pair of observed features. Also, Chi-squared test was applied for observing differences in the frequencies of the phenotypic characteristics of the hand between the genders. Following traits were shown to have a statistically significant association: midphalangeal hair-Hitchhiker’s thumb, midphalangeal hair – digital index, midphalangeal hair – nail shape, midphalangeal hair – crooked fifth finger, Hitchhiker’s thumb- extensibility of proximal joint of thumb, digital index – nail shape, digital index -crooked fifth finger, midphalangeal hair – hand clasping, crooked fifth finger – hand clasping. Analysis of differences in the frequencies of the observed phenotypic traits of the hand according to the genders showed statistical significance for D, Dht, Ref and Lf.