山西地区线粒体DNA11778突变所致Leber遗传性视神经病变外显率分析

目的　分析山西地区线粒体 DNA11778位点突变者外显率。方法　应用等位基因特异性PCR检测视神经病变者线粒体DNA11778位点 ,对突变者及其母系成员进行分析。结果　在 30个家系中 17个家系仅先证者患病 ,另 13个家系除先证者外母系亲属有 72人携带该位点突变 ,其中 4 0人出现临床症状。结论　山西地区线粒体 DNA11778位点突变者外显率达 5 5 .6 %。     

线粒体DNA11778突变所致Leber遗传性视神经病变外显率分析

目的 分析携带线粒体DNA（mitochondrialDNA,mtDNA)11778突变者视神经病变的外显率。方法 对经基因诊断确定为mtDNA11778突变的Leber遗传性视神经病变（Leber hereditary optic neuropathy,LHON)家系进行分析。确定mtDNA11778突变携带者及患者。结果 16个家系中mtDNA11778突变携带者130人,其中男65人,女65人,130人突变携带者中43人患病,外显率33.1%。男性患者34人,男性外显率52.3%,女性患者9人,女性外显率13.8%,男女患病比率3.8:1,患者中男性占79%。结论 携带纯合性mtDNA11778位点突变的中国人,LHON外显率近1/3。     

Clinical, genetic, and biochemical characterization of a Leber hereditary optic neuropathy family containing both the 11778 and 14484 primary mutations.

Four mitochondrial DNA (mtDNA) mutations at nps 3460, 11778, 14484, and 14459 account for roughly 90% of cases of Leber hereditary optic neuropathy (LHON) and are designated as "primary" LHON mutations since they act as major predisposition factors for LHON. Although each primary mutation can arise independently on different mtDNA backgrounds during human evolution, they characteristically do not co-occur in LHON patients. We report here a family with the simultaneous occurrence of the 11778A and 14484C mutations. Neuro-ophthalmological examination of the proband, a nine-year-old Caucasian female, revealed the bilateral optic atrophy, central scotomas, and reduced visual acuity typical of LHON. Her mother had normal appearing optic discs and is today visually asymptomatic. Analysis of the proband blood mtDNA revealed that she harbored both the 11778A (heteroplasmic, 94% mutant) and the 14484C (homoplasmic mutant) mutation. This genotype was maintained in proband lymphoblasts and transmitochondrial cybrids. The mother also had both mutations, with the 14484C mutation homoplasmic in all cell types examined. However, only 31% of her blood mtDNAs carried the 11778 mutation, which segregated to essentially 100% wild-type in lymphoblast and cybrid mtDNA. Complex I-linked respiration and specific enzyme activity were consistently lowest in proband lymphoblast and cybrid mitochondria compared to those from the mother, 11778A patients, 14484C patients, or controls, thus demonstrating both a deleterious synergistic interaction between the 11778A and 14484C mutations and the magnitude of 11778A-associated complex I dysfunction. Remarkably, spontaneous vision recovery occurred in the proband, highlighting the complexities encountered when associating mtDNA genotype and complex I function with LHON expression.     

On the many faces of Leber hereditary optic neuropathy

Leber hereditary optic neuropathy (LHON) is a maternally inherited disorder, associated with mutations in the mitochondrial DNA, which is notorious for its aspecific presentations. Two pedigrees are described with cases that are atypical for LHON with respect to sex, age of onset, interval between the eyes becoming affected, course of the disease, concomitant disorders, additional test results, final visual acuity, and/or results of mtDNA analysis. Moreover, the pedigrees themselves did not suggest maternal inheritance. We analysed the diagnostic and clinical genetic difficulties related to the atypical aspects of these pedigrees. We conclude that mtDNA analysis is justified in every case of optic nerve atrophy with no clear cause. Identification of one of the three LHON specifically associated mtDNA mutations is essential to confirm the diagnosis.     

The unique characteristics of Thai Leber hereditary optic neuropathy: analysis of 30 G11778A pedigrees

Leber hereditary optic neuropathy (LHON) is characterized by acute or subacute bilateral visual loss, and affects mostly young males. The most common mitochondrial DNA mutation responsible for LHON worldwide is G11778A. Despite different genetic backgrounds, which are believed to influence the disease expression, most features of LHON are quite common in different populations. However, there seem to be a few ethnic-specific differences. Analyses of our 30 G11778A LHON pedigrees in Thailand showed some characteristics different from those of Caucasians and Japanese. In particular, our pedigrees showed a lower male to female ratio of affected persons (2.6:1) and much higher prevalence of G11778A blood heteroplasmy (37% of the pedigrees contained at least one heteroplasmic G11778A individual). Heteroplasmicity seemed to influence disease manifestation in our patients but did not appear to alter the onset of the disease. The estimated overall penetrance of our G11778A LHON population was 37% for males and 13% for females. When each of our large pedigrees were considered separately, disease penetration varied from 9 to 45% between the pedigrees, and also varied between different branches of the same large pedigree. Survival analysis showed that the secondary LHON mutations G3316A and C3497T had a synergistic deleterious effect with the G11778A mutation, accelerating the onset of the disease in our patients.     

Transmission of heteroplasmic G11778A in extensive pedigrees of Thai Leber hereditary optic neuropathy

Leber hereditary optic neuropathy (LHON) is characterized by the acute or subacute bilateral painless loss of central vision, predominantly in young males. G11778A is the most common mitochondrial DNA mutation responsible for the disease. Thirty-seven percent of our LHON pedigrees (which is a much higher prevalence than that generally found) carried heteroplasmic G11778A. Analyses of four large Thai LHON pedigrees spanning four to six generations strongly suggested that the transmission of the heteroplasmic G11778A mutation is under selective pressure in favour of the mutated allele and that heteroplasmy influences the disease expression.     

Molecular epidemiology of mtDNA mutations in 903 Chinese families suspected with Leber hereditary optic neuropathy

We report the molecular epidemiology of three primary mutations in mitochondrial DNA (mtDNA) responsible for Leber hereditary optic neuropathy (LHON) based on analysis of probands suspected with LHON from 903 Chinese families. Most of them had optic neuropathy of unknown cause, and only 128 had a family history of optic neuropathy. Mutations in the mtDNA were detected in 346 probands. Of the 346 cases, 340 were homoplasmic and only six were heteroplasmic; 284 were male and 62 were female; 120 had a family history and 226 were sporadic. G11778A, T14484C and G3460A mutations were detected in 312 (90.2%), 30, and four families, respectively. The majority (226/346, 65.3%) of all LHON cases in Chinese are sporadic. These 226 probands (29.2%) were identified from 775 probands with sporadic optic neuropathy. Affected male-to-female ratio was 4.6:1 for all probands but was 2.2:1 for family members. Average age at onset was 18.5 years, ranging from 4.5 to 47 years old.     

Intrafamilial variation in Leber hereditary optic neuropathy revealed by direct mutation analysis

Leber hereditary optic neuropathy (LHON) has been associated with a mitochondrial mutation at position 11,778 in the ND4 gene in about 50% of families. Individuals from six Swedish families with LHON were investigated for the presence of this mutation using allele-specific oligonucleotides and a sensitive chemoluminescent detection system. The point mutation was seen in mitochondrial DNA extracted from leukocytes in five families, four of which showed a homoplasmic pattern. One family showed a heteroplasmic pattern and one family was negative for the mutation. Six adults without impaired vision from three LHON families were detected as carriers with a degree of mutated mitochondrial DNA similar to that in affected relatives. The results show that the penetrance of LHON varies remarkably among carriers of the 11,778 mutation within families. We conclude that the prognosis for carriers should be stated cautiously when interpreting results from mutation analysis of mitochondrial DNA in leukocytes.     

Leber遗传性视神经病变线粒体DNA三个原发性突变位点的研究

目的 通过对Leber遗传性视神经病变(Leber's hereditary optic neuropathy,LHON)线粒体DNA ND4 11778G＞A、ND1 3460G＞A和ND6 14484T＞C 3个原发性突变位点序列分析,阐明LHON患者发病的分子机理.方法 PCR扩增35例患者的上述3个原发性突变位点所在的区段,PCR产物直接测序分析.结果 35例患者中,6例存在ND4 11778 G＞A突变位点,1例存在ND1 3460 G＞A突变位点,未检出ND6 14484 T＞C突变位点,3个原发性突变位点的检出率为20.0％(7/35).35例患者均存在ND4 11719G＞A同义突变,除此突变位点外,23例(65.7％)患者共计筛出21个突变位点,2种突变类型.其中13例患者存在单个突变位点,8例存在2个突变位点,2例存在3个突变位点.21个突变位点中,ND4 11778G＞A突变频率最高,为28.6％(6/21); ND1 3552 T＞A、ND6 14470 T＞C、ND4 11794 T＞C、ND1 3497 C＞T和3644 T＞C位点突变频率依次为19.0％(4/21)、19.0％(4/21)、14.3％(3/21)、9.5％(2/21)和9.5％(2/21).3例存在ND4 11794 T＞C突变位点的患者,2例为异质性突变,1例为同质性突变.结论 LHON患者线粒体DNA ND4 11778G＞A、ND1 3460G＞A和ND6 14484T＞C 3个原发性致病突变中,以ND4 11778 G＞A为主;继发性突变位点ND1 3552 T＞A或ND1 3644 T＞C单独或协同原发性突变位点ND4 11778 G＞A导致LHON的发生,与单纯携带ND4 11778 G＞A的患者相比视力受损较弱.     

Asian-specific mtDNA backgrounds associated with the primary G11778A mutation of Leber's hereditary optic neuropathy

We studied 19 patients of Southeast Asian (SEA) ethnic ancestry with Leber's hereditary optic neuropathy (LHON) to investigate the mtDNA haplotypes associated with the primary mutation(s). Eighteen patients carried a mitochondrial DNA (mtDNA) G11778A mutation (Arg340His in the respiratory complex I ND4 subunit), while one had a T14484C mutation (Met64Val in the ND6 subunit). One patient had a class II LHON mtDNA mutation, G3316A. Sequencing data of the ND genes showed many single-nucleotide polymorphisms (62 SNPs in 17 individuals; 10 LHON patients and 7 normal controls) not previously reported in Europeans or Japanese. The SEA G11778A LHON mutation was associated mostly with two mtDNA haplogroups, M (47%) and a novel lineage, characterized by the gain of a 10394 DdeI site but absence of the 10397 AluI site, designated BM (37%). A significant association was observed between one SNP, A10398G, resulting in a Thr114Ala substitution in the ND3 subunit, and the primary LHON mutation. This SNP also characterizes haplogroup J, with which the European LHON 11778 and 14484 mutations show preferential association. The combination of A10398G and other SNPs, specific for the haplogroups J, M, or BM, might act synergistically to increase the penetrance of the LHON mutations, thus allowing their detection. Received: June 6, 2002 / Accepted: August 23, 2002 Acknowledgments We thank Dr. Mulia Sitepu, School of Medicine, University of Atmajaya, Jakarta, Drs. Norma Handoyo and Inakawati Rivai of the School of Medicine, University of Diponegoro, Semarang, and Dr. Tjahyono Ghondowiardjo of the School of Medicine, University of Indonesia, for referring their patients for DNA analysis. This work was supported by grants from PT Krakatau Steel and PT Inti through the Agency for Strategic Industries (Indonesia) and by a generous development fund from the National Development Planning Agency (BAPPENAS) of the Republic of Indonesia. Correspondence to:S. Marzuki     

Leber's hereditary optic neuropathy with 14484 mutation in Central Java,Indonesia

Leber's hereditary optic neuropathy (LHON) is a maternally inherited late-onset form of blindness characterized by acute or subacute bilateral retinal degradation resulting in a permanent loss of central vision. G11778A, C3460A, and T14484C mutations on mitochondrial DNA (mtDNA) are specific for LHON and account for most, but not all, worldwide LHON cases. A six-generation Indonesian LHON family with the T14484C mutation was analyzed. Polymerase chain reaction/restriction fragment length polymorphism analysis showed that all of the maternal lineages had the T14484C mutation in a homoplasmic form. Penetrance of the disease (33.3%) and male predominance (3:1) was similar to other worldwide LHON with the T14484C mutation. The incidence of offspring born to affected mothers was no different from that of unaffected mothers, and the age distribution of cases was no higher than that of asymptomatic carriers. Eight secondary mutations were sought but not detected. The patients of this family belonged to haplogroup M. These findings support the idea that the mtDNA backgrounds involved in the expression of LHON mutations in southeast Asians are different from those of Europeans.T. Nishioka and M. Tasaki contributed equally to this work     

Leber遗传性视神经病三个家系患者线粒体DNA突变位点的研究

目的对Leber遗传性视神经病（Leber’s hereditary optic neuropathy，LHON）家系的原发突变位点11778与继发突变位点9804、13708、13730、15257进行突变分析，探讨两者之间相关性及对LHON的影响。方法应用聚合酶链反应一单链构象多态性和DNA测序对3个LHON家系37位母系成员和47名正常人的线粒体DNA（mitochondrial DNA，mtDNA）进行检测。结果16例患者及其母系亲属均存在11778位点突变，未发现9804、13708、13730、15257位点突变，但DNA测序发现13759、13928、13942、15301、15326、15323这6个新突变位点。结论3个家系都存在mtDNA11778位点突变，在13759位点患者突变率远高于正常人，差异有统计学意义（P〈0．001），表明13759是LHON新的继发突变位点。     

Leber遗传性视神经病变线粒体DNA突变的研究

目的 探讨Leber遗传性视神经病变患者的线粒体DNA突变类型及特点.方法 分别应用等位基因特异性PCR（MSP-PCR）、聚合酶链反应-限制性片段长度多态性（PCR-RFLP）和聚合酶链反应-单链构象多态性（PCR-SSCP）联合DNA测序的方法,对12个家系中21位临床症状疑诊为LHON的患者及其19位无明显眼疾的母系亲属进行线粒体DNA检测.结果 40例受检者中35例发生11778位点突变,2位成员有3460位点突变,有1例发现有4258位点突变（A→G）.结论 11778是LHON患者常见的突变位点,3460突变少见,新发现的突变位点4258可能是新的继发突变或基因多态性.     

伴有mtDNA14484位点突变的Leber病一大家系

目的 研究Leber病一大家系的遗传因素,探讨其外显率、遗传早现、自发视力恢复,以及与mtDNA的关联性.方法 对家系中18例患者进行调查,并行视力、眼底等常规检查;5例患者作了视觉诱发电位(visual evoked potential,VEP)及视野检查;应用聚合酶链反应对6例患者外周血液进行mtDNA11778、3460及144843个位点检查.结果 (1)本家系第Ⅰ代娶二妻,前妻后代皆无明显诱因出现双眼视力下降,经眼底镜检查符合视神经萎缩诊断.后妻无眼病,其后代均无眼病.(2)6例患者的mtDNA检查显示11778、3460位点未发现突变,而在14484位点出现同质性突变.结论 该家系Leber病呈典型母系遗传,该病的临床表现可能与mtDNA14484位点突变密切关联.     

Phylogenetic analysis of Leber's hereditary optic neuropathy mitochondrial DNA's indicates multiple independent occurrences of the common mutations

The mitochondrial DNAs (mtDNA) from 17 Caucasian 11778-positive and 30 Caucasian 11778-negative Leber's hereditary optic neuropathy (LHON) patients were PCR-amplified and subjected to high resolution restriction endonuclease analysis. Concurrently, all patient mtDNAs were screened for the common primary LHON mtDNA mutations at nucleotide pairs (nps) 3460, 11778, and 14484, the ambiguous intermediate-risk LHON mtDNA mutations at nps 5244 and 15257, and the secondary LHON mtDNA mutations at nps 3394, 4216, 4917, 7444, 13708, and 15812. Phylogenetic analysis was performed using mtDNA haplotype data from the 47 LHON patients and 175 non-LHON Caucasian controls. The superimposition of the LHON mutation screening results upon the Caucasian mtDNA phylogeny revealed (1) 35 different LHON haplotypes, (2) that all three common primary mutations have occurred multiple times in Caucasians, (3) that while recurrent mutation is common for the primary mutations, secondary mutations tend to be lineage-specific, (4) that the np 15257 mutation was confined to a single mtDNA lineage but may be etiologically important in some LHON cases since it was found in a LHON pedigree which lacked a common primary mutation; complete sequence analysis of the proband mtDNA revealed only a single other candidate missense mutation (at np 10663 of the ND4L gene) of uncertain pathological significance; and (5) that the np 14484 mutation may be less pathogenic than either the np 3460 or np 11778 mutations, as this mutation most commonly occurred on a single mtDNA lineage and almost always in association with secondary LHON mutations. A phylogenetic ageneous disease has thus provided key genetic data bearing on the relative pathogenicity of the LHON-associated mtDNA mutations. © 1995 Wiley-Liss, Inc.     

中国人Leber 遗传性视神经病变的原发突变及临床特征

目的 分析中国人Leber遗传性视神经病变(Leber’s hereditary optic neuropathy,LHON)线粒体DNA3个原发致病基因突变遗传及其临床特征。方法 分别用突变特异性引物聚合酶链反应,异源双链-单链构象多态性,限制性片段长度多态性和DNA测序方法,对110个家系的156例LHON患者进行11778A、3460A、14484C 3个原发位点检测,并收集患者病史及其临床资料,进行统计学分析。结果 110例LHON先证者中,11778位点突变者100例,占90．9％;3460位点突变者2例,占1．8％;14484位点突变者8例,占7,3％。不同突变位点的LHON患者发病时视力分布：125人(250眼)11778位点突变患眼中发病时视力≤0．01(占17．6％),视力介于0.01至0．1之间(占52．1％),视力≥0．1(占30．3％);28人(56眼)14484位点突变患眼中无患眼视力低于0．01视力介于001至0．1之间(占12．7％),视力≥0．1(占87．3％);3人(6眼)3460位点突变患眼视力均介于0．03至0．08之间。视力恢复情况：250只11778位点突变的患眼中,6．97％的眼视力有所恢复,平均最终视力0．03(指数～0．07);56只14484位点突变的患眼中,50％的眼视力有所恢复,占50％,平均最终视力0．8(0．3～1．2)。结论 中国人LHON患者mtDNA 3个原发致病突变中,以11778A位点突变为主、14484C位点突变较少、3460A罕见。LHON的临床表现与致病突变位点有关,14484C突变患者的发病视力及视力恢复情况明显好于11778A患者。     

线粒体tRNAThr A15951G可能是与Leber遗传性视神经病变相关的基因突变

目的 进一步分析中国汉族Leber遗传性视神经病变(Leber's hereditary optic neuropathy,LHON)家系的临床和分子遗传学特征,阐明LHON的分子致病机制.方法 对2例具有典型LHON临床特征的先证者和家系其他成员进行眼科学及其临床检查.对这2个家系先证者使用24对有部分重叠的引物进行线粒体DNA(mitochondrial DNA,mtDNA)全序列扩增分析.结果 检查发现这些家系成员中视力损害的外显率分别为5.3％(1/19)、18.2％(4/22).经mtDNA测序分析,并没有发现mtDNA G11778A、G3460A和T14484C 3个常见的突变,在tRNAThr上发现了A15951G同质性突变位点.线粒体DNA全序列分析显示2个家系呈现mtDNA多态性,都属于东亚单倍型D4b1.A15951G突变位于线粒体tRNAThr高度保守区(通用位点为71位),可能导致tRNA空间结构和稳定性发生改变,线粒体蛋白合成功能受损,最终发生视力损害.结论 线粒体tRNAThr A15951G可能是与Leber遗传性视神经病变相关的致病性线粒体基因突变.     

中国Leber遗传性视神经病变G11696A突变两个家系分析

目的对两个中国Leber遗传性视神经病变(Leber’shereditary optic neuropathy,LHON)家系的临床和分子遗传学特征进行分析。方法眼科临床检查发现在这两个家系中只有先证者1人出现视力障碍,发病年龄分别为10岁和17岁。对这两个家系先证者使用24对有部分重叠的引物进行线粒体DNA(mitochondrial DNA,mtDNA)全序列扩增分析。结果没有发现mtDNAG11778A、G3460A和T14484C3个常见的突变位点,而发现了与LHON相关的ND4G11196A同质性突变位点的存在,在167名正常对照只发现1例G11696A突变。结论线粒体DNA全序列分析发现两个家系呈现独特的mtDNA多态性,都属于东亚单体型D4。不完全外显率和正常对照频率(1/167)表明G11696A突变本身不足以导致LHON的发生,说明其它因素在这两个LHON家系的表型表达中也起一定的作用。在这些家系mtDNA中缺乏影响重要功能突变位点的存在,排除了线粒体背景对LHON临床表型的影响。因此,核修饰基因、环境因素可能对两个中国G11696A突变家系的外显率和发病严重程度起促进作用。     

A mutation of mitochondrial DNA in Japanese families with Leber's hereditary optic neuropathy

Leber's hereditary optic neuropathy (LHON) is a maternally inherited disease characterized by optic nerve degeneration associated with severe bilateral visual loss in young men and occasionally in women. A mitochondrial DNA (mtDNA) replacement mutation in LHON patient, G to A transition at nucleotide position (nt) 11778 converting the 340th arginine to histidine in the NADH dehydrogenase subunit 4, was detected asSfaNI site polymorphism (Wallaceet al., Science,242: 1427–1430, 1988). To evaluate if theSfaNI site loss can be used to diagnose LHON patients, mtDNAs from peripheral blood of six affected males including five probands from five unrelated Japanese families with LHON, a pair of parents and a normal sister of one of the probands and 4 control persons were analyzed using PCR amplification method. The mutation of leukocyte mtDNA at nt 11778 was identified in all of the affected patients, the normal mother and the sister examined, while the father who is normal and 4 control persons did not show the change. These findings support that the mutation at nt 11778 is also associated with LHON in the Japanese and the test of theSfaNI site loss described here is useful for confirming the clinical diagnosis of LHON patients with the mutation at nt 11778.     

继发突变位点对Leber's遗传性视神经萎缩作用机制的研究

目的探讨继发突变位点在Leber’s遗传性视神经萎缩(Leber’s hereditary optic neuropathy,LHON)疾病发生发展中的作用。方法对4个LHON家系患者及家系男性子代进行3个原发位点、24个继发位点及相邻片段检查。结果4家系均携带11778位点突变,所查患者无24个继发位点突变,但在这些位点的相邻片段上有5178、5108、3705、3721、13734等多个多态位点存在。结论线粒体多态位点具有家族遗传性,在LHON继发位点研究中应同时进行男性子代检查,以排查突变位点是否具有致病性。"修复基因"的存在可能对LHON疾病发展有影响。