Abstract: Interdigital pattern distribution in 101 nuclear families is analyzed, and the genes of this phenotype controlling either Ⅲ or Ⅳ area, right or left hand are all on the same locus. Genes controlling Ⅲ or Ⅳ area is mosaic dominant. One gene controls a couple of corresponding areas on both right and left hands. Different genes' phenotypes have different asymmetric degrees. There are 6 kinds of perfectible dominant genes and one inperfectible dominant gene. This is interdigital pattern' s major gene locus. There also finds a Ⅲ pattern' s recessive gene very occasionally. These genes' frequen- cies in random population are calculated. This heredity mode can be applied to parentage identification etc.

Key words: Interdigital patterns; Left-right asymmetry; Mosaic dominance; Pedigree analysis; Major gene inheritance; Gene frequencies