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

Introduction 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 in 48 children with ASD and in 41  control child was 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 19.0 software, considering as significant less than .05 (p < .05). Results: Results showed that the average ratio of 2D:4D in ASD children were lower than the ratio in control children (P