A Comparison of Obsessive Compulsive Disorder, Pervasive Developmental Disorder, and Control Groups in Terms of 2D:4D Ratio and Finger Lengths

Objective: Obsessive compulsive disorder (OCD) and autism share some common features, such as repetitive behaviors. Second finger to fourth finger ratio (2d: 4d) is thought to be associated with prenatal androgen exposure and differs between the sexes and 2d:4d ratio is reported to be more "masculine like features" in autism. The aim of this study is to compare OCD and autism that display common features in terms of 2d: 4d ratio and finger lengths. Methods: This study included 15 boys diagnosed with OCD, 12 boys diagnosed with Pervasive Developmental Disorder (PDD), and 54 healthy boys with no psychiatric disorders between the ages of 6 and 18 years. The diagnoses of OCD and PDD were reached after detailed clinical evaluations according to DSM IV-TR criteria. After the evaluation, the children's and adolescents' hand length, hand width, and finger lengths were measured with a digital compass. Results: In this study, we found no statistically significant difference between the control, OCD, and PDD groups regarding the right and left 2d: 4d ratio. Whereas in the PDD group, we found that the right hand second and third fingers and the left hand second, third, and fourth fingers were shorter than the fingers of those in the control group. We also found that left hand length was shorter in the PDD group than in the OCD group and the second finger of the right hand and third finger of left hand was shorter in the PDD group than in the OCD and control groups. Conclusion: In this study, we did not observe any differences between the OCD, PDD, and control groups in terms of 2d: 4d ratio; however, we found that that some finger lengths were shorter in the PDD group than in the control group. This result may be a dysmorphological sign that could be screened in the PDD group, but we need further research with larger sample sizes to confirm its significance