The Ratio of Second to Fourth Digit Length (2D:4D) in Children with Autistic Disorder

Emerging hypotheses suggest a causal role for prenatal androgen exposure in some cases of Autism spectrum disorders (ASD). The ratios of the lengths of the bones of the 2nd to the 4th digits (2D:4D) are purported to be markers for prenatal androgen exposure and to be established early in gestation. Ratio of second and fourth digits (2D:4D) is usually used as a proxy for prenatal testosterone.Methods and Materials: In this study, 2D:4D on 48 children with ASD (Case group) and in 41 normal child (Control group) were measured. Two groups were matched with the gender and age. Both groups were selected by convenience sampling method. All statistical analyses were performed using SPSS version 19 software, considering as significant less than. Results showed that the average ratio of 2D:4D in ASD children were lower than the ratio in control group (P<0.05(. 2D to 4D finger-length ratio of the right of children with autism was lower than the normal children (P<0.05(; while this difference was not significant between the two groups in the left hand (P>0.05(. The results indicate that the 2D:4D ratio could be used together with other parameters as an indicator of the likelihood of developing autistic traits in offspring. Results achieved in this research can be valuable in further biological and psychological approaches in neurocognitive research and diagnostics of children from ASD.