In addition to the identical T14502C mutation, as shown in Table 2, these subjects exhibited distinct sets of mtDNA polymorphism. Of other nucleotide changes in these mitochondrial genomes, there are 21 known variants in the D-loop, four known variants in 12S rRNA gene, two known variants in the 16S rRNA gene, the known G5824A mutation variant in the tRNACys gene, the A8296G variant in the NC7, the T15900C variant in the tRNAThr gene, 37 silent variants (one novel) in the protein-encoding
PF2341066 as well as 19 missense mutations in the protein-encoding genes [7]. These missense mutations are the T3866C (I187T) in the ND1 gene, the C6268T (A122V) in the CO1 gene, the T8618C (I31T), A8701G (T59A), T8821G (S99A), A8860G (T112A), and G9053A (S176N) in the A6 gene, the G9966A (V254I) in the CO3 gene, the A10398G (T114A) in the ND3 gene, the T10609C (M47T) in the ND4L gene, the T10908C (F50S) in the ND4 gene, the G12406A (V20I), G13135A (A267T), G13759A (A475T), and G13928C (S531T) in the ND5 gene, the C14766T (T7I), T15071C (Y109H), A15218G (T158A), and A15326G (T194A) in the Cytb gene. These variants in RNAs and polypeptides were further evaluated by
phylogenetic analysis of these variants and sequences from other organisms including mouse [26], bovine [27], and Xenopus laevis [28]. Here, I187T in the ND1, A122V in the CO1, S99A in the A6, and V254I in the CO3 gene exhibited evolutionary conservation among these four organisms. However, none of the other variants showed evolutionary conservation. Based on the nomenclature of mitochondrial haplogroups [29] and [30], we used the mtDNA sequence variations among three Chinese probands to establish the haplogroup affiliation of each mtDNA. Here, mtDNAs of pedigree WZ401, WZ402, and WZ403 belong to the Eastern Asian haplogroups M10a, F1a1, and H2, respectively.
