Klaudia Kyselicová
Institute of Physiology, Faculty of Medicine, Comenius University, Bratislava, Slovakia
Title: Is 2nd to 4th Digit Ratio a Reliable Biomarker for Autism Spectrum Disorders ?
Biography
Biography: Klaudia Kyselicová
Abstract
The 2D:4D ratio (second to fourth digit ratio) is sexually dimorphic; males of different population studied so far, had lower 2D:4D than females. It is generally assumed that the sexual dimorphism is established during early prenatal development under the influence of sex hormones and the 2D:4D ratio is supposed to remain stable after early prenatal stages. Proponents of the „extreme male brain „theory suggested that an increased androgen exposure in utero may contribute to the development of autism spectrum disorders. The aim of our study was to test whether 2D:4D is sexually dimorphic, stable and a valid biomarker for autism.
Our results showed a significant difference (P = 0.0001) in the digit ratio of the right hand and sexual dimorphism in the expected direction – females (N = 86) had, on average, the ratio of 0.979 and males (N = 86) the ratio of 0.96 in Slovak adult population . This sexual dimorphism in 2D:4D ratio occurred even in children of the same population, in girls (N = 52) the average digit ratio was 0.957, while in boys (N = 56) the average digit ratio was 0.945. However, our findings also suggest that the 2D:4D ratio does not remain constant throughout the life span, but slowly increases in a stable manner during childhood. Very significant differences could be found in the digit ratio of Slovak boys and girls when compared to adults for both the right hand (P = 0.0031 boys, P < 0.0001 girls) and left hand (P = 0.0068 boys, P = 0.0177 girls). After testing whether this ratio correlates with the Autism quotient of adults diagnosed with Asperger’s syndrome, no correlation was assessed. Our study indicates that the 2D:4D ratio could not be a reliable biomarker for autism spectrum disorders. This study was supported by grant APVV 15-0045 and APVV 15-0085.
Recent Publications (minimum 5)
1. Baron-Cohen S (2002) The extreme male brain theory of autism. Trends in Cognitive Sciences 6:248-254.
2. Trivers R, Manning J, Jacobson A (2006) A longitudinal study of digit ratio (2D:4D) and other finger ratios in Jamaican children. Hormones and Behavior 49:150-156.
3. Malas MA, Dogan S, Evcil EH, Desdicioglu K (2006) Fetal development of the hand, digits nad digits ratio (2D:4D). Early Human Development 82:469-475.
4. Manning JT, Bundred PE, Newton DJ, Flanagan BF (2003) The second to fourth digit ratio and variation in the androgen receptor gene. Evolution and Human Behavior 24:399-405.
5. Manning JT, Stewart A, Wilson J, Lewis-Jones DI (2004) Sex and ethnic differences in 2nd to 4th digit ratio of children. Early Human Development 80:161-168.