2D:4D ratio in adult female and their comparison with males: An anthropometric study from Northern India.

Abstract

Background: 2D:4D ratio is a sexually dimorphic marker that act as potential marker of prenatal androgen exposure. Genital development in fetus depends on adequate and timely exposure to sex steroids. Assessment of fetal androgen levels and exposure are essential to predict normal development and future reproductive disorders. The 2D:4D ratio can be used to assess androgen action. Aim: This study attempts to find out 2D:4D ratio of left and right hand in adult females and males and to find out whether any difference exists among these variables in males and females. Methods: A total of 83 adults were included in the study. There were 51 females and 32 males. The distance of second finger and fourth finger was calculated from mid-point of proximal most digital crease to distal most end of the finger. The ratio was then obtained by dividing second finger length by fourth finger length. Result: The mean 2D: 4D ratio of left hand and right hand in adult female were 0.98 and 0.99 respectively. The mean 2D: 4D ratio of left hand and right hand in adult male were 0.967 and 0.99 respectively. The males have lower 2D:4D ratio for left and right hand as compared to females. The mean 2D:4D ratio of left hand and right hand in left handed females were 0.99 and 1.01 respectively while mean 2D:4D ratio of left hand and right hand in right handed females were 0.987 and 0.99. The mean 2D:4D ratio of left hand and right hand in left handed males were 0.96 and 0.98 respectively while mean 2D:4D ratio of left hand and right hand in right handed males were 0.98 and 1.01. Conclusion: Sexually dimorphic markers are variables that can be used as indirect marker of fetal androgen exposure. In this study the mean 2D:4D ratio in males for both left and right hand was lower than females in overall group and in case of both right and left handedness males and females. Male fetuses with higher testosterone levels will have a lower 2D:4D ratio. Digital ratio is an easy noninvasive parameter, abnormal 2D:4D ratio in females can predict excessive androgen action.