Are 2D: 4D finger-length ratios an indicator of androgenetic alopecia in males?

ABSTRACT

Abstract BACKGROUND: Although the pathogenesis of androgenetic alopecia is not completely understood, the roles of genetic susceptibility and androgens are well-known. A lower ratio of the second digit (index finger = 2D) to the fourth digit (ring finger = 4D) length has been hypothesized to reflect prenatal androgen exposure and/or higher sensitivity to androgens. OBJECTIVES: To determine the relationship between the second to fourth digit length ratio and androgenetic alopecia. METHODS: Finger length measurements were made by a digital vernier calliper. Androgenetic alopecia severity was assessed using the Hamilton-Norwood scale. Subjects with an androgenetic alopecia score of grade III or more were included in the study. RESULTS: A total of 189 males with androgenetic alopecia and 171 healthy controls were enrolled in the study. The age range of participants was 19-65 years. The 2D4D ratios in patients with androgenetic alopecia were significantly lower than those of healthy controls for the right hand; however, no significant difference was found for the left hand. Average 2D4D ratios in androgenetic alopecia patients were also lower than in controls. No significant relationship was observed between androgenetic alopecia severity and 2D4D ratios. CONCLUSION: Our data support the anatomical evidence of in utero androgen exposure and/or an individual’s sensitivity to androgens in patients with androgenetic alopecia. Furthermore, the right hand 2D4D ratio might be an indicator of androgenetic alopecia development.