The relationship between carpal tunnel syndrome and the 2D:4D digit ratio: A systematic review.

Carpal tunnel syndrome is a common peripheral neuropathy influenced by multiple biological and anthropometric factors. The 2D:4D digit ratio, a marker of prenatal androgen exposure, has recently been investigated for its association with carpal tunnel syndrome risk. This systematic review aimed to evaluate the relationship between 2D:4D ratio and carpal tunnel syndrome development, considering anthropometric variables. Four studies including a total of 672 participants were analyzed. Two of the studies were conducted on populations with the same ethnic background, while the other two involved individuals from different ethnic groups. The included studies assessed 2D:4D ratios alongside various anthropometric parameters such as body mass index. Across the four included studies, three consistently demonstrated that a lower 2D:4D ratio is associated with an increased risk of carpal tunnel syndrome, particularly in females. The findings suggest that 2D:4D may serve as a potential biomarker for carpal tunnel syndrome, especially in populations with higher susceptibility, such as women. Three of the four studies highlighted female gender as a common risk factor for carpal tunnel syndrome. Additionally, a lower 2D:4D ratio was associated with increased carpal tunnel syndrome risk in three studies, suggesting that this ratio reflecting prenatal androgen exposure may serve as a potential biomarker for carpal tunnel syndrome.