An Investigation of the Relationship Between 2D:4D ratio and Respiratory Function Parameters

Abstract

Introduction: Second digit/fourth digit (2D:4D) ratio is determined by dividing the length of the index finger(2D) by the length of the ring finger (4D). 2D:4D ratio is described as a dimorphic trait which is decided early in foetal development. It is described as dimorphic as males tend to have a slightly lower 2D:4D ratio than females. Previous research studies have suggested correlations made between the ratio of the lengths of the second and fourth digits and td, the level of exposure to oestrogen that individuals undergo while in utero. Other studies have shown there to be a definitive correlation between 2D:4D ratio and foetal hormone exposure and a correlation between foetal hormone exposure and respiratory function, it was hypothesised that there is a correlation between 2D:4D ratio and respiratory function. Methodology: In total, 50 male and female students were recruited to participate in this study. Both smokers and non-smokers were included. All participants were required to read an information sheet and sign a consent form. Once consent was obtained, each student was required to complete a data sheet with their individual information required to carry out the necessary test. The lengths of each students second and fourth digits were determined using digital Vernier callipers and the digit ratio was calculated. All students respiratory function was measuredmeasured, and this enabled us to calculate the fForced vVital cCapacity (FVC) and the fForced eExpiratory vVolume in oOne sSecond (FEV1). All data from the vitalograph alpha and the 2D:4D ratios of all participants were recorded and analysed on an Excel spreadsheet. Results: There is a significant difference between the predicted and actual respiratory parameter values for VC, FVC and FEV1 as the p-values for these tests were <0.05 with the mean values for the predicted VC,FVC and FEV1 being 4.23 (±0.98), 4.17 (±0.87) and 3.60 (±0.68) respectively and actual VC, FVC and FEV1 being 3.47 (±1.16), 3.64 (±1.02) and 3.10 (±1.10) respectively, however there was no significant difference between the predicted and actual values for the FVC: FEV1 ratio as the p- value was greater than 0.05. All Pearson correlations between right hand digit ratio and all respiratory function parameters, such as right handright-hand digit ratio and predicted vital capacity, which had an r-value of 0.24, were not significant. Discussion: The results of this study are contradictory to the working hypothesis and also contradicted the work of Park et al. This contradiction suggestsed that second to fourth digit ratio is not viable as a biological marker for respiratory function, particularly in the student population. Key Words: 2D:4D ratio, Vitalograph alpha, Lung Functionality, Prenatal Hormones