Prenatal Hormonal Markers in Individuals With Joint Hypermobility: The Role of the 2D : 4D Digit Ratio

OBJECTIVES: Exposure to sex hormones during the early stages of fetal development in the prenatal period is thought to affect the length ratio of the second and fourth fingers (2D:4D). The 2D:4D ratio remains a subject of significant interest, particularly in relation to diseases and conditions linked to gender differences. This study aims to compare the 2D:4D ratio of individuals with generalized joint hypermobility (GJH) to the ratio of individuals without GJH in a population of both male and female participants. METHODS: The study was conducted on 180 individuals (100 females), including 85 with GJH and 95 without GJH (controls). Joint hypermobility was assessed using the Beighton score. The 2D:4D ratio was calculated using a digital caliper. In addition, the height, weight, and body mass index of the participants were calculated. RESULTS: The 2D:4D ratio was significantly higher in individuals with GJH compared to controls. In males, the 2D:4D ratio was higher in both the right and left hands in the GJH group compared to controls (p < 0.05). In females, the 2D:4D ratio was also significantly higher in both hands in the GJH (p < 0.05). The Beighton total score showed moderate positive correlations with right- and left-hand 2D:4D ratios (r = 0.49 and r = 0.38, respectively; p < 0.001). CONCLUSION: The 2D:4D ratio can be used as a potential biomarker for GJH. It is thought that the concentration of sex hormones in the prenatal period (2D:4D ratio) may affect joint hypermobility (connective tissue). TRIAL REGISTRATION: ClinicalTrials.gov: NCT07157930.