Analysis of mitochondrial DNA polymorphisms in Guangdong Han Chinese

Previous investigations on Chinese mitochondrial DNA (mtDNA) variation revealed that the matrilineal gene pool of southern Han Chinese is rather complex, with much higher genetic diversity and more basal/ancient lineages than the northern Hans. The extreme case is Guangdong Han populations, among which pronounced (matrilineal) differentiation has been observed, indicative of complex demography of the region. To get more insights into the maternal makeup of southern Han Chinese, mtDNA variation of a total of 106 individuals sampled from Dongguan, Guangdong Province, China, was analyzed in this study. With the aid of the information from control-region hypervariable segments I and II (HVS-I and -II) as well as some necessary coding-region segments, the phylogenetic status of all mtDNAs under examination were determined according to the reconstructed East Asian mtDNA tree. In this way, the mtDNAs have been classified into various haplogroups or sub-haplogroups. The southern-prevalent haplogroups, such as R9 (20.8%), B (17.9%), M7b (14.2%), show relatively high distribution frequencies in Dongguan Hans; whereas the frequencies of Northern-prevalent haplogroups (with the exception of D) are quite low: C (1.9%), G2 (1.9%) and Z (1.9%), indicating the southern-origin of Dongguan Hans.