Investigating the Relationship Between 2D:4D Digit Ratio and Respiratory Function
Background: Prenatal androgen exposure is said to play a role in lung development, whereby 2D:4D digit ratio has been used as a biological marker for prenatal sex hormone exposure. Digit ratio a sexually dimorphic trait where males tend to have a longer ring finger relative to their index finger is known as low 2D:4D ratio, as opposed to females exhibiting a higher 2D:4D ratio. Studies have suggested a relationship between prenatal exposure, determined by 2D:4D, and pulmonary function and capacity. However, currently published studies are limited. Objectives: To measure and investigate 2D:4D digit ratio using a digital calliper and to measure respiratory function using a Vitalograph alpha to determine if a significant correlation exists between an individual’s 2D:4D digit ratio and respiratory function. Comparisons using Microsoft Excel 2016 were also conducted between lung function and genders and the total population, smokers, ethnicities and height. Methodology: 50 volunteers had participated in the study, where each individual had answered a simple questionnaire and allowed the measurement of their finger lengths using a digital calliper, height, weight, as well as lung functions., measured using a Vitalograph Alpha Spirometer. The subjects were then divided into groups of males (n=13) and females (n=37) and Caucasian. (n=46) and non-Caucasian (n=4), and smokers (n=5) and non-smokers (n=45) to be analysed using either a Pearson’s Correlation or a student’s paired and independent t-test statistical tests. Results: There were no significant correlation between digit ratio and all of the actual lung function tests within the total, female or male population. The mean digit ratio lower in men (0.98±0.04) than females (1,00±0.04), however it was non-significant. Although, the men’s predicted and actual respiratory function test were significantly higher, where VC (5.73±0.40 v. 4.90±0.97), FVC (5.49±0.38 v. 4.94±0.55), FEV1 (4.58±0.31 v. 4.31±0.74), than the women: VC (3.70±0.40 v. 2.97±0.71), FVC (3.71±0.38 v. 3.18±0.69), FEV (3.25±0.38 v. 2.68±0.8). The men also had a larger lung capacity (VC) as opposed to the women of the study (F= 2.97±0.71 v. M= 4.90±0.97; p<0.0001). Conclusion: Our results did not support the existing studies, as no significant correlations between 2D:4D digit ratio and the lung parameters was observed. This suggests that the predictive functions of 2D:4D ratio on respiratory function is, therefore, not reflective of prenatal androgen exposures among individuals. Although, larger-scaled studies have shown differing results which may have been due to the limitations within this study. While correlations were non-significant, an individual’s overall lung functions may instead be determined by other factors. Key Words: 2D:4D ratio; lung function; prenatal androgens.