Association Between Hand Digit Ratio (2D:4D) and Nonsyndromic Orofacial Clefts

Abstract

Objectives: Digit ratio (2D:4D) has been considered to be a marker in studies evaluating an individual's susceptibility to diseases, especially those diseases that show sex differences in their occurrence. We aimed to assess whether 2D:4D ratios are associated with nonsyndromic cleft lip and/or palate (NSCL/P) and verify the existence of a specific pattern of 2D:4D ratio in individuals affected by orofacial clefts.

Design: This was a case-control study.

Methods: Digital measurements of index and ring finger lengths of both hands of patients with NSCL/P (n = 54) and age- and gender-matched controls (n = 54) were obtained using a digital vernier caliper. Mean ratios between the second and fourth digits were compared. Data were analyzed by Student's t test and Mann-Whitney test with a significance level of 5%.

Results: No significant difference was found between the mean digit ratios of the right and left hands between the groups for any analysis (P > .05), neither for the whole sample nor for the distributions by type of cleft and by gender.

Conclusions: Although the development of the fingers and the occurrence of NSCL/P can be regulated by the actions of similar genes, our results are not consistent with an association between 2D:4D ratio and this craniofacial deformity. This suggests that intrauterine exposure to fetal androgens, assessed using this marker, is similar between patients with NSCL/P and healthy individuals. We highlight the need for further studies in populations with different ancestries.

Keywords: 2D:4D; cleft lip; cleft palate; digit ratio.