Classification tree of the mtDNA haplogroups observed in Han Chinese. The diagnostic mutations considered here (relative to the revised CRS; Andrews et al. 1999) are indicated on the branches. Nucleotide changes are specified for transversions by suffixes, and “d” indicates deletion; mutations recurrent in this tree are underlined. The revised CRS differs from the root of haplogroup R by mutations at 73, 2706, 7028, 11719, and 14766 that are characteristic of HV or H and by seven private mutations at 263, 315+C, 750, 1438, 4769, 8860, and 15326 (Andrews et al. 1999).