INHERITANCE STUDIES IN DERMATOGLYPHICS

Variability in dermatoglyphics is absolute in that no human individual has exactly the same phenotype as any other individual in either space or time. Because of this dermatoglyphics presents a fascinating area to study human variation and its underlying genetic power structure. The great extent of variation lends itself well to the study of variation but the unlimited nature of phenotypes encountered has made attempts at a genetical analysis difficult. The total variability has led to dermatoglyphics being utilized as an identification medium and because of the enormous practical advantages involved a large volume of literature has resulted on systems of classification of phenotypes, devised specifically to differentiate one individual’s prints from hundreds of others recorded previously. The stress on individual differentiation has led to a considerable amount of minutiae being considered in such classifications. N o consistent attempt was made, while this work of improving the classification of dermatoglyphic phenotypes was being developed, to search for underlying causative factors. Most workers, searching for genetic information, used the basic classification already set up and have succeeded partially in establishing certain features of inheritance. The information garnered so far on the inheritance of dermatoglyphics is far from being definitive because of (1) The phenotypes considered are invariably those set up originally for identification purposes, and (2) The areas of ridged skin examined are often very fragmentary and localized. Investigators have been bound within the traditions of the “arch, loop, whorl” categories and consider fingers and palms completely separately. Even on the fingers only the apical area is considered, the basal and medial sections being ignored. With the advent of new knowledge concerning the relationship of dermatoglyphics with adverse clinical conditions and chromosomal abnormalities a new urgency has arisen in ascertaining the genetic processes in dermatoglyphics. Studies are now being done on the association of different dermatoglyphic traits and various abnormal conditions. This has further aroused interest in the inheritance of such associated traits. The need to look more closely at inheritance mechanisms led to studies on communities in India. Two endogamous groups from Andhra Pradesh, India, the Kammas and Reddis, were examined to procure samples of 100 males each. All known classifiable traits were correlated on both fingers and palms. The author’s hypothesis is that complexity upon the first three radial digits is correlated positively with complexity of patterning upon the radial side of the palm and that the same holds true for the last two ulnar digits. Thus it may be more feasible to investigate inheritance mechanisms in dermatoglyphics using both fingers and palms divided by a vertical axis running between the third and fourth digits, as two units, than considering the fingers as one unit and the palm as another. The correlation matrix for Kammas, and that for Reddis are reproduced here (TABLES 1 to 4).