The inheritance of palmar and hallucal dermatoglyphic patterns in fifty-four American Caucasian families.

We searched for single gene effects determining certain palmar and plantar patterns - two interdigital and the hypothenar areas, palmar main line sequence, and hallucal pattern. Our subjects were 108 parents from central Louisiana and 123 of their offspring; there were 127 females and 104 males. For the third and fourth interdigital areas, we classified for presence of a pattern (+) or no pattern (-). For the hypothenar area, we classified arch, anteform, and open field as no pattern (-) and other configurations as a pattern (+). Main line sequence we determined by the distal to proximal ordering of the five main lines. We analyzed the hallucal area by combining three loop patterns. Segregational analyses followed. For the third interdigital area, the frequency of + was 51%. For the fourth interdigital area, the frequency of + was 45%. We set out the six mating types by the bilateral occurence of pattern in each area and found similar results. The proportion of ++ offspring was highest with both ++ parents and diminished as the parents became increasingly more --. Evidence for genetic determination of six different main line sequences consisted of the proportion of related/(related + unrelated) which averaged 0.48. Parent-offspring occurrence of an accessory triradius and absence of the c triradius suggested monogenic control. Segregation of the hallucal patterns was less suggestive. We conclude that the results offer evidence for substantial genetic determination of palmar dermatoglyphics, and for some patterns possible monogenic determination.