Mitochondrial DNA haplogroups M7b1'2 and M8a affect clinical expression of leber hereditary optic neuropathy in Chinese families with the m.11778G-->a mutation.
Leber hereditary optic neuropathy (LHON) is the most extensively studied mitochondrial disease, with the majority of the cases being caused by one of three primary mitochondrial DNA (mtDNA) mutations. Incomplete disease penetrance and gender bias are two features of LHON and indicate involvement of additional genetic or environmental factors in the pathogenesis of the disorder. Haplogroups J, K, and H have been shown to influence the clinical expression of LHON in subjects harboring primary mutations in European families. However, whether mtDNA haplogroups would affect the penetrance of LHON in East Asian families has not been evaluated yet. By studying the penetrance of LHON in 1859 individuals from 182 Chinese families (including one from Cambodia) with the m.11778G-->A mutation, we found that haplogroup M7b1'2 significantly increases the risk of visual loss, whereas M8a has a protective effect. Analyses of the complete mtDNA sequences from LHON families with m.11778G-->A narrow the association of disease expression to m.12811T-->C (Y159H) in the NADH dehydrogenase 5 gene (MT-ND5) in haplogroup M7b1'2 and suggest that the specific combination of amino acid changes (A20T-T53I) in the ATP synthase 6 protein (MT-ATP6) caused by m.8584G-->A and m.8684C-->T might account for the beneficial background effect of M8a. Protein secondary-structure prediction for the MT-ATP6 with the two M8a-specific amino acid changes further supported our inferences. These findings will assist in further understanding the pathogenesis of LHON and guide future genetic counseling in East Asian patients with m.11778G-->A.
Ji
Yanli
Y
State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
Zhang
A-Mei
AM
Jia
Xiaoyun
X
Zhang
Ya-Ping
YP
Xiao
Xueshan
X
Li
Shiqiang
S
Guo
Xiangming
X
Bandelt
Hans-Jürgen
HJ
Zhang
Qingjiong
Q
Yao
Yong-Gang
YG
D044466:Asian People / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D005190:Family; D005260:Female; D006239:Haplotypes; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009154:Mutation; D029242:Optic Atrophy, Hereditary, Leber / Q000235:genetics*; D010375:Pedigree; D017422:Sequence Analysis, DNA; D012737:Sex Factors
D004272:DNA, Mitochondrial