The Study of Fingerprint Ridge Density in a Sample of Egyptian Population and its Application for Sex Identification

Abstract

Fingerprints have been used widely in human identification. The possibility of sex identification using fingerprints was based on a hypothesis that males have coarser ridges than females. The aim of the present work was to study the fingerprint ridge density as a method of sex identification in a sample of young Egyptian population. A cross sectional statistical study was carried out on 200 volunteers; 100 males and 100 females (age from 21 to 30 years). The epidermal ridges were counted in two distal (radial and ulnar) and one proximal region of each fingerprint. The radial and ulnar squares were placed directly on the radial and ulnar side of the central core region, while the proximal square was placed diagonally by placing one of its corners over the intersection of the joint line with the center line. The fingerprint mean ridge density of the three regions in all fingers, radial, ulnar and proximal regions were calculated and compared. Receiver–operating characteristic curves for predicting the probability of female gender were generated. Fingerprint ridge densities in the distal regions were significantly greater than in the proximal region in both sexes. Females showed significantly higher ridge density in the three regions for each and all fingers. The mean ridge density in all fingers at a cut off value >11.87 ridges/ 25mm2 has a positive predictive value (PPV) of 90.09% for females, while the mean ridge density in radial region at a cut off value >12.2 ridges/ 25mm2 has PPV of 86.96%. It is concluded that fingerprints are valuable in sex is identification in Egyptian population based on fingerprint ridge density. In addition, ridge density can be considered as a morphological feature for individual variation.