Mitochondrial DNA polymorphism in Japanese. I. Analysis with restriction enzymes of six base pair recognition.

The mitochondrial DNA (mtDNA) from 120 Japanese was analysed with 15 restriction enzymes that recognize six base pairs, of which 11 enzymes showed at least one atypical cleavage pattern. Digestion patterns with Hinc II and Hae II were highly polymorphic. The observed restriction enzyme morphs were classified into 22 types of distinct cleavage patterns. By pairwise comparison of each restriction type, the average number of nucleotide substitutions per nucleotide site (delta) was estimated at 0.00417, which agreed with the values obtained from other human populations in previous studies. There were 11 site gains, of which seven were transitions and four were transversions. Phylogenetic analysis of the present data suggested that the Japanese population conceals a considerably high degree of mtDNA diversity.