The Study Of MtDNA Mutation In Leber Hereditary Optic Neuropathy

Objective To investigate the mtDNA mutation in Leber hereditary optic neuropathy (LHON) patients, and identify the mtDNA mutation type and features.Methods Blood samples from 12 families, which include 21 patients and 19 healthy maternal members , were simultaneously analyzed using mutation specific primer polymerase chain reaction (MSP-PCR) , restriction fragment length polymorphisms (PCR-RFLP) technique , polymerase chain reaction combined single strand conformation polymorphism (PCR-SSCP) and DNA sequencing.Results (1) There were 35 members who habored mutation and there were 2 members who did not habored mutation in MSP analysis of the mtDNA mutation at np11778 . 19 members who contain 12 men and 7 women were ill and 16 members were healthy in 35 members who habored 11778 mutation, so the mutable penetrance of 11778 mutation is 54.3% . (2) There were 2 members habored heterozygosity mutation and there were 38 members who did not habored mutation in RFLP analysis of the mtDNA mutation at np3460 . Only one male member was ill and the other was healthy, so the mutable penetrance of 3460 mutation is 50% . (3) SSCP analysis of the mtDNA mutation showed band shift in two lanes. The two members were male patients . DNA sequencing revealed np4258 A to G . It did not follow primary mutation at np11778 and 3460 . (4) On the whole, there were 38 members who habored mtDNA mutation in 40 subjects of 12 families . 21 members had clinical symptom , so the mutable penetrance of mtDNA mutation is 55.2%. 21 patients contain 14 males and 7 females . It indicated the penetrance of man was prominent higher than woman .Conclusion (1) Primary mutation at np11778 is overwhelming majority in China . In our test, the ratio of mutation is 87.5% (35/40); Primary mutation at np3460 is relatively minor .The ratio of mutation is 5 % (2/40) in this test; The novel mutation at np4258(A→G)may be a original secondary mutation point or single nucleotide polymorphism in normal individuals ? (2) Only part of mitochondrial DNA mutation carries can onset, because the disease has visible incomplete penetrance and deviation of sex . (3) Because the primary mutation at np11778 is predominant in China ,it should be regarded as a routine test in diagnosis of patient and member of LHON pedigrees . (4) Two methods- Restriction fragment length polymorphisms and mutation specific prime polymerase chain reaction are convenient , specific and economic ,because they are aim directly at some mutations , which have definite mutable site and character . They are used routine test in clinical diagnosis and empirical study ; Even though two methods-single strand conformation polymorphism and DNA sequencing arecomplicated, they can be used bolting and identity those novel mutations.