The influence of sex chromosomes on finger dermatoglyphic patterns.

Finger pattern frequencies for patients exhibiting various sex chromosome aneuploidies were obtained from literature sources. The sample consisted of 141 XO, 500 XX, 68 XXX, 9 XXXX, 500 XY, 93 XYY, 30 XXYY and 6 XXXXY. Pattern frequencies were converted to radial and ulnar loop frequencies, and these in turn were used to construct four variables; pattern intensity; radial-ulnar difference; radial loop asymmetry; and ulnar loop asymmetry. The relationship between the dermatoglyphic variables on to the sex chromosomes was examined by regressing the dermatoglyphic variables on to the number of X and Y chromosomes. Radial-ulnar difference and radial loop asymmetry showed the strongest relationship with the number of X and Y chromosomes. The X and Y chromosomes had about equal influence on radial-ulnar difference, but the Y had a stronger effect on radial loop asymmetry. It is postulated that sex chromosomes influence dermatoglyphic development by controlling tissue sensitivity to fetal sex steroids.