Mutation frequency analysis of mitochondrial ND1 gene associated with Leber hereditary optic neuropathy in Chinese population / 中华实验眼科杂志

Background Leber hereditary optic neuropathy (LHON)is a common inherited eye disease,which generally affects young adults with bilateral loss of central vision.Mutation frequency of Leber hereditary has not been fully clarified. Objective This study was to investigate the mutation frequency of mitochondrial NDI gene associated with LHON in Chinese population. Methods The proposal of the study was approved by Ethic Committee of Wenzhou Medical College.Written informed consent was obtained from each subject initial of this trial.Eight hundred and ninety-four LHON patients and 134 normal subjects were collected.Genomic DNA was extracted from peripheral blood leukocytes of the all participants.Polymerase chain reaction (PCR) was used to amplify and sequence analysis of the mitochondrial ND1 gene was performed and aligned with revised Cambridge Reference Sequence(rCRS) of mitochondrial DNA.Then mutated gene frequency was screened and analyzed. Results Mutational analysis of mitochondrial ND1 gene in 894 LHON patients revealed the presence of G3316A,T3394C,G3460A,C3497T,G3635A,G3733A,and T4216C.11.19％ LHON patients (100/894 ) were found to be associated with the gene mutations mentioned above,and 3.24％ patients (29/894) showed the co-occurrence of three primary mutations.Mutation frequencies in LHON patients were 2.57％,2.23％,1.45％,3.80％,0.67％,0.11％,0.34％,respectively,and G3316A,T3394C,C3497T and T4216C also were detected in 134 normal controls with the mutation frequencies of 4.48％,2.99％,4.48％ and 1.49％,respectively.Mutation frequency analysis showed an insignificant difference in the mutations of G3316A,T3394C,C3497T and T4216C between LHON patients and normal controls (x2 =0.926,P=0.336;x2 =0.052,P=0.820; x2 =0.142,P=0.707;P=0.129).G3376A,G3496T,G3700A,A4136G,T4160C and C4171A were absent in Chinese LHON patients. Conclusions Mitoehondrial ND1 gene in LHON is a mutational hotspot in Chinese population,11.19％ (100/894)associated with LHON was caused by ND1 gene mutation.G3635A,G3733A may be rare pathological mutation in Chinese population.However,G3316A,T3394C,C3497T and T4216C are insufficient to produce the clinical phenotype,but they may play a synergic role for penetrance and phenotypic manifestation in LHON.

The mitochondrial tRNA(Thr) A15951G mutation may be associated with Leber's hereditary optic neuropathy in two Chinese families / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To explore clinical, genetic and molecular features of two Chinese Han families with Leber's hereditary optic neuropathy (LHON).</p><p><b>METHODS</b>Ophthalmologic examinations revealed variable severity and age-at-onset of visual loss among probands and other matrilineal relatives of both families. The families exhibited extremely low penetrance of visual impairment. The entire mitochondrial genome of two probands was amplified by PCR in 24 overlapping fragments using sets of oligonucleotide primers.</p><p><b>RESULTS</b>Sequence analysis of complete mitochondrial genome in the pedigrees excluded three common LHON associated mutations G11778A, G3460A and T14484C, but revealed the presence of a known homoplasmic tRNA(Thr) A15951G mutation. It also showed distinct sets of mtDNA polymorphisms belonging to Eastern Asian haplogroup D4b1. The A15951G mutation is located at the extremely conserved nucleotide (conventional position 71) of tRNA(Thr). Thus, this mutation may alter the structure and stability of mitochondrial tRNA(Thr), thereby leading to a failure in the tRNA metabolism and mitochondrial dysfunction, causing visual impairment.</p><p><b>CONCLUSION</b>The results suggested that the A15951G mutation might be involved in the pathogenesis of Leber's hereditary optic neuropathy in the two families.</p>

Leber's hereditary optic neuropathy is associated with the mitochondrial G11696A mutation in two Chinese families / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To report the clinical, genetic, and molecular characterization of two Chinese families with Leber's hereditary optic neuropathy (LHON).</p><p><b>METHODS</b>Ophthalmological examinations showed that only probands in two families exhibited visual loss at the age of 10 and 17 years respectively. The entire mitochondrial genome of two probands was PCR amplified in 24 overlapping fragments using sets of oligonucleotide primers.</p><p><b>RESULTS</b>Mutational analysis of mitochondrial DNA (mtDNA) in these pedigrees revealed the absence of three common LHON associated G11778A, G3460A and T144484 mutations but the presence of homoplastic LHON associated ND4 G11696A mutation, which was present in one out of 167 Chinese healthy controls.</p><p><b>CONCLUSION</b>Sequence analysis of the complete mitochondrial genomes in two pedigrees showed the distinct sets of mtDNA polymorphisms, belonging to Eastern Asian haplogroup D4. The incomplete penetrance of visual loss and the presence of one in 167 controls suggested that this mutation itself is insufficient to produce a clinical phenotype and other modifier factors play a role in the phenotypic manifestation. The lack of functional mtDNA variants in these pedigrees ruled out the role of mitochondrial background in the phenotypic expression of visual loss. Therefore, nuclear modifier gene(s) or environmental factor(s) may play a role in the phenotypic expression of the LHON-associated G11696A mutation in two Chinese pedigrees.</p>