Digit ratio 2D:4D is a possible indicator for androgenetic alopecia in males

Abstract

Background: Androgenetic alopecia (AGA) is the most common hair loss. The 2D:4D digit ratio refers to the ratio of the length of the second finger to that of the fourth finger and is thought as a marker of prenatal androgen exposure.

Objectives: There are many studies which have examined the relationship between 2D:4D ratio and some other diseases. In this study, we evaluated the relationship between digit ratio 2D:4D and AGA.

Methods: The study group was composed of a male with AGA and healthy controls. The lengths of patients' second and fourth fingers were measured using a digital caliper with a resolution of 0.01 mm. Finger length was measured on the palmar side of the hand from the basal metacarpophalangeal crease. The 2D:4D ratio was obtained by dividing the length of the second finger by the length of the fourth finger.

Results: A total of 99 males who have androgenetic alopecia with a score of grade III or more and 90 controls were included. The mean age of AGA group was 29.72 ± 5.53, and the mean age of control group was 19.63 ± 5.05. The left-hand 2D:4D ratios of AGA group (0.893 ± 0.267) were significantly lower than healthy controls (0.971 ± 0.028). No significant relationships were found between AGA severity, age of onset,and digit ratios.

Conclusions: The left-hand digit ratio 2D:4D is lower in AGA patients, and therefore, left-hand digit ratio 2D:4D can be used as an estimation tool for AGA development in future. There is not any correlation between digit ratio and age of onset. Also, there is no correlation between digit ratio 2D:4D and AGA severity.

Keywords: alopecia; androgens; digit ratio.