Comparison of Second and Fourth Digit Lengths in Individuals with Autism Spectrum Disorder and Controls among the Hausa Population of Kano, Nigeria

Globally, there has been a rise in autism spectrum disorder (ASD), impacting nearly one in every 160 children. However, its prevalence in many low- and middle-income countries remains uncertain. Although ASD has been connected to various bodily characteristics, its link to digits has been scarcely explored, particularly among the Hausa population. This study aimed to compare 2D and 4D digits between individuals with ASD and controls in the Hausa population of Kano State, Nigeria. The study was a cross-sectional comparative study, and using convenience sampling, 48 students aged 8 to 19 years (24 with ASD and 24 controls) participated in the study. Direct anthropometric measurements of the second (2D) and fourth digits (4D) of both hands were taken, and the digit ratios were calculated accordingly. Normality of data distribution was assessed with the Shapiro-Wilk test, while independent sample t-tests and Mann-Whitney U tests were used to compare means between groups. Results showed that although ASD participants generally had higher mean 2D and 4D lengths of both hands, no significant differences were observed in the 2D:4D ratios between ASD and control groups overall. However, when stratified by sex using independent sample t-tests and Mann-Whitney U tests, males with ASD exhibited a significantly greater right 2D length compared to controls (P = 0.030). No significant sexual dimorphism was found within the digit parameters of either group. This study suggests that while digit lengths may differ in males with ASD, the 2D:4D digit ratio may not be a distinguishing marker for ASD in this population.

Key Words: Autism spectrum disorder, Digit ratio (2D:4D), Hausa population, neurotypical controls, anthropometry