Sexual dimorphism in ratio of second and fourth digits and its relationship with metabolic syndrome indices and cardiovascular risk factors

Abstract

Background: Ratio of second and fourth digit (2D:4D) is known to be germane in analyzing utero concentrations of testosterone and estrogen in human and other vertebrates. 2D:4D had been linked several traits like athletes’ abilities, reproductive success, risk of cancer and cardiovascular disease (CVD). Metabolic syndrome (MetS) is a clustering of several cardiovascular risk factors. Waist circumference (WC), neck circumference (NC), body mass index (BMI) and waist-to-height ratio (WHtR) are important in measuring MetS. This study investigated sexual dimorphism in 2D:4D and its relationship with MetS indices and CVD factors among adult residing in Ilorin, North central Nigeria. Materials and Methods: This is a cross-sectional, stratified multi-staged sampling study. Participants residing in different neighborhoods were visited at home where finger lengths and anthropometric traits were measured.Participants include 801 healthy adults aged 18-44 years (56% male) who had been living in the area for more than 3 years. Results: Males showed significantly lower 2D:4D than females (unpaired t-test; t [699] = 11.49, P = 0.001). A significant positive correlation was observed in MetS markers and 2D:4D. WHtR showed the highest correlation with 2D:4D in male (r = 0.461, P ≤ 0.001) and female (r = 0.408, P ≤ 0.001) when compared with BMI, NC and WC. All positive correlations recorded in this study were high in male and right hand. Conclusion: Our results showed that 2D:4D is sexual dimorphic and right hand 2D:4D as a predictor of MetS is better. We concluded that 2D:4D is a proxy for MetS and CVD risk factors in Ilorin.

Key words: Cardiovascular disease, digit ratio, metabolic syndrome, sexual dimorphism