Goldenhar 综合征家系的临床表型和遗传学分析

目的分析1组Goldenhar综合征家系的临床表现及遗传学特征。方法我们随访到1组4代33人的Goldenhar综合征家系，对目前存活的29人进行了临床表型和遗传学的初步分析。结果家系内有Goldenhaar综合征患者5人．临床表现具高度多样性，累及眼、耳、脊柱、颜面、口腔等多个器官和系统的发育不良，在遗传方式上属于常染色体显性遗传。从细胞遗传学水平对家系中成员进行染色体检查，未发现核型异常。结论该Goldenhar综合征家系属常染色体显性遗传，染色体检查未发现核型异常。     

应用遗传学分析方法诊断遗传性血小板减少综合征

目的对一血小板减少症伴巨型血小板家系进行遗传学分析,分析其基因突变位点,确定其发病机制。方法采用PCR与测序相结合的方法对血小板减少症家系进行遗传学分析。结果此家系为MYH9基因突变相关的常染色体显性遗传性血小板减少综合征。结论遗传学分析可以辅助确诊遗传性血小板减少综合征。     

一个常染色体显性遗传Emery-Dreifuss型肌营养不良家系的基因突变分析

目的 探讨一个常染色体显性遗传Emery-Dreifuss型肌营养不良(Emery-Dreifuss muscular dystrophy,EDMD)家系的临床、病理及遗传学特点.方法 收集家系中2例患者(先证者及女儿)的临床资料及骨骼肌标本,行组织化学染色病理分析;收集先证者及家系成员(3代7人)血液DNA标本,采用聚合酶链反应和DNA直接测序方法 对LMNA基因进行突变检测;明确基因变异位点后对家系行单倍型分析.结果 先证者具有典型的EDMD临床表现:关节挛缩、进行性加重的肌无力和肌萎缩、心脏传导异常;骨骼肌活检病理示肌源性合并轻度神经源性改变;2例患者LMNA基因第9外显子发现杂合错义突变1583(C→G)(T528R),表型正常的其他家系成员未发现该突变;单倍型分析显示先证者及女儿具有相同的致病单倍型.结论 报道了中国人常染色体显性遗传EDMD患者的表现型及基因型.     

一个常染色体显性遗传非综合征性耳聋家系的HBSY-012家系基因检测及遗传学特征分析

目的 研究常染色体显性遗传非综合征性耳聋家系的HBSY-012家系致病基因的突变位点，分析基因型与异常表型的关系。方法 采集一个常染色体显性遗传性非综合征型耳聋HBSY-012家系患者的临床资料，分析耳聋表型、遗传方式，并绘制家系图。提取家系成员外周血DNA，利用耳聋相关基因靶向测序，对家系成员进行全基因组外显子测序，寻找致病基因，采用Sanger测序技术验证突变位点。结果 HBSY-012家系现存四代共19人，9人诊断为感音神经性聋，耳聋表型特点为语后聋，发病早期呈现高频感音神经性耳聋，双耳对称，随着疾病进展出现渐进性听力下降，且快速下降，并转变成全频受累的极重度感音神经性耳聋。该家系的9例患者均在5～7岁开始出现听力下降，患者中年龄最大68岁，最小10岁。HBSY-012家系系谱分析该家系符合常染色体显性遗传特征。遗传性耳聋基因筛查检测显示EVI5基因NM＿005665:c.2399C>T变异、ANKMY2基因NM＿020319:c.822＿826del变异以及CCDC50基因c.363C>T(p.Leu121Phe)杂合突变，其中CCDC50基因c.363C>T...     

两个有血缘关系的常染色体显性非综合性耳聋家系基因突变分析

目的 对两个有血缘关系的常染色体显性非综合性耳聋家系进行基因定位及突变分析,确定其致病基因.方法 通过家系调查和临床检查,鉴定了两个有血缘关系的常染色体显性非综合性耳聋大家系.并对已知位点及基因进行连锁分析,对致病基因在染色体上进行定位.PCR扩增候选基因MYH14基因的所有外显子和外显子-内含子交界区,直接测序法进行突变检测.结果 将这两个家系的致病基因定位于DFNA4位点,最大连锁值为4.94.具有统计学意义.突变检测发现MYH14基因的杂合突变c.359T>C(p.S120L),DNA直接测序确证两家系的所有患者均携带该突变,而家系中正常人则均不携带该突变.结论 第1次在中国非综合性耳聋家系中发现MYH14基因的突变,表明MYH14基因突变也是导致中国人非综合性耳聋的原因.     

Ⅰ型神经纤维瘤一家系4例的分析报告

目的 分析一个面部有巨大神经纤维瘤家系的临床表现及遗传方式.方法 根据美国国立卫生研究院(NIH)提出的神经纤维瘤诊断标准进行诊断,通过染色体检查和家系分析方法确定遗传方式.结果 家系12名成员中有3名患者表现出Ⅰ型神经纤维瘤的4项临床特征,染色体检查无异常,家系分析表现出常染色体显性遗传特点.结论 该家系为Ⅰ型神经纤维瘤家系,遗传方式为常染色体显性遗传.     

不完全外显的遗传性痉挛性截瘫一家系临床与致病基因排除定位分析

目的 描述一个遗传了4代的不完全外显的遗传性痉挛性截瘫(hereditary spastic paraplegia,SPG)大家系的临床特征,并进行致病基因排除定位分析.方法 对SPG家系内11例患者的临床资料进行回顾性分析,并采用荧光多重PCR、毛细管凝胶电泳、Linkage软件包,选择对已定位常染色体显性遗传致病基因位点附近微卫星标记进行连锁分析.结果 该SPG家系的11例患者的发病年龄2～10岁,表现为缓慢进展的双下肢僵硬无力,四肢肌张力轻度增高,双上肢为主的腱反射亢进,剪刀步态和病理征阳性,无小便失禁或尿频、感觉障碍、眼震、痴呆等;遗传学分析该家系符合常染色体显性遗传,但外显不完全,连锁分析和突变分析发现该家系与已知的常染色体显性遗传SPG致病基因位点不连锁.结论 该SPG家系具有典型的"单纯型"痉挛性截瘫临床特点,发病年龄早,上肢体征较下肢明显,遗传学分析不支持该家系与已定位常染色体显性遗传位点相连锁,是一种新的SPG亚型.     

先天性白内障的分子遗传学研究进展

先天性白内障(congenital cataract)是指在孕期或胎儿期由于各种因素使晶状体发育受到影响,是儿童致盲的首要原因之一.先天性白内障有明显的临床异质性和遗传异质性,一般与晶体蛋白基因、缝隙连接蛋白基因、转录因子基因及其他基因突变有关,常见的遗传方式有常染色体显性遗传、常染色体隐性遗传和性染色体连锁遗传,其中以常染色体显性遗传最为常见.近几年先天性白内障的分子遗传学水平有了新的突破,此文就其研究进展进行综述.     

广西染色体结构异常的不育者家系遗传研究

目的 探讨广西不育患者中染色体结构异常家系的遗传方式、遗传概率及家系中染色体异常携带者妊娠结局。方法 在广西筛选60例染色体平衡易位或倒位的不育患者，对家系所有成员行细胞遗传学分析，染色体遗传图谱绘制，并对染色体异常患者进行生育指导。结果 生育正常及携带者子代的遗传概率远高于理论值，经生育指导及产前诊断，共成功生育子代42人，无缺陷儿出生。结论 染色体异常在家系中通过携带者稳定遗传，染色体异常类型和断裂位点会导致不同程度的临床表现，对子代的生育影响有所差别，尽早检出家系的染色体异常携带者并在合适的育龄生育至关重要。     

182例遗传咨询者外周血染色体分析

我室1992、11至1993、10遗传咨询中，对182例患者采用自体血浆半量培养法培养外周血淋巴细胞染色体，常规制片显带分析。在就诊原因中，查出染色体异常核型23例，占受检者12．6％，其中常染色体结构异常核型6例，占受检者3．3％．性染色体异态性Yq 17例，占9．3％。发现一种新型异常染色体，经湖南医科大学细胞遗传学国家培训中心鉴定为世界首报桉型(一家系二代中4人)。     

Dissecting clinical findings: platelet defects segregate independently of deafness and cataract in a family affected by an apparent syndromic form of macrothrombocytopenia

We studied a family with a suspected diagnosis of MYH9-related disease, which is one of the most common forms of autosomal dominant macrothrombocytopenias associated with hearing impairment, cataracts and nephritis. No mutation of the MYH9 gene was identified. Moreover, the A156V variant of the GPIbalpha gene, responsible for 30% of macrothrombocytopenias in Italy, was not detected in the family. Therefore, we hypothesized that the clinical symptoms were caused by mutations in different genes. The screening of the candidate genes for deafness and/or cataract allowed us to identify two variants, M34T and S19T, of the GJB2 gene in family members with hearing impairment. Because of the relatively common occurrence of inherited hearing loss and, at least in the Mediterranean area, of platelet macrocytosis, the two traits occurred by chance in the same family and mimicked the MYH9-related disease.     

Clinical and molecular genetic analysis of a family with macrothrombocytopenia and early onset sensorineural hearing loss

A kindred with inherited macrothrombocytopenia (MTCP) and sensorineural hearing loss (SNHL) from Ghent, Belgium was identified. Currently, joint expression of MTCP and hearing loss are linked to mutations within MYH9 only. Thus, we tested the hypothesis that a mutation within MYH9 is responsible for the autosomal dominant inheritance of MTCP and hearing loss in the Ghent family. A mutation screen of MYH9 coding region including its intron–exon junctions, as well as common hearing loss genes GJB2, GJB3, and GJB6, was performed. However, no pathogenic sequence alteration was identified. Patients' leukocytes were determined to be normal for NMMHC-A distribution via immunofluorescence analysis and free of Döhle body-like inclusions, identified as aggregates of mutant NMHC-IIA in MYH9 disorders. Also, western blot analysis with anti-NMHC-IIA antibody identified a single 220 kDa immunoreactive band with normal expression level of NMHC-IIA within the platelets and leukocytes of the affected family members. The immunoblot analysis eliminates the possibility of a large deletion within MYH9 that can escape detection by direct sequencing. Collectively, these results suggest that molecular genetic etiology of the Ghent family disorder may be due to as yet unidentified gene whose mutation(s) yields a phenocopy of the MYH9-related disease.     

MYH9-related disease: Five novel mutations expanding the spectrum of causative mutations and confirming genotype/phenotype correlations

MYH9-related disease (MYH9-RD) is a rare autosomal dominant syndromic disorder caused by mutations in MYH9, the gene encoding for the heavy chain of non-muscle myosin IIA (myosin-9). MYH9-RD is characterized by congenital macrothrombocytopenia and typical inclusion bodies in neutrophils associated with a variable risk of developing sensorineural deafness, presenile cataract, and/or progressive nephropathy. The spectrum of mutations responsible for MYH9-RD is limited. We report five families, each with a novel MYH9 mutation. Two mutations, p.Val34Gly and p.Arg702Ser, affect the motor domain of myosin-9, whereas the other three, p.Met847_Glu853dup, p.Lys1048_Glu1054del, and p.Asp1447Tyr, hit the coiled-coil tail domain of the protein. The motor domain mutations were associated with more severe clinical phenotypes than those in the tail domain.     

Identification of the first duplication in MYH9-related disease: A hot spot for unequal crossing-over within exon 24 of the MYH9 gene

MYH9-related disease (MYH9RD) is a rare autosomal dominant disorder caused by mutations in MYH9, the gene encoding the heavy chain of non-muscle myosin IIA. All patients present with congenital macrothrombocytopenia and inclusion bodies in neutrophils. Some of them can also develop sensorineural deafness, presenile cataracts, and/or progressive nephritis leading to end-stage renal failure. The spectrum of mutations so far identified is peculiar, consisting of mostly missense mutations. Others are nonsense and frameshift mutations, all localized in the COOH terminus of the protein, or in-frame deletions. We report a family with three affected members carrying a novel mutation, the first duplication (p.E1066_A1072dup), of MYH9. The mutation was localized within exon 24, where the presence of a 16 nucleotide repeat was likely to be responsible for unequal crossing-over. Of note, a deletion of the same amino acids 1066_1072 was also identified in another MHY9RD family. Since two of the four patients with the duplication or the deletion in exon 24 were affected with bilateral neonatal cataracts, we speculate that these mutations might correlate with the ocular defect, which is reported only in 16% of MYH9RD patients.     

Familial hydrocephalus with normal cognition and distinctive radiological features

Hydrocephalus is a clinically and genetically heterogeneous condition. Individuals with posterior fossa abnormalities have an increased risk of developing hydrocephalus. The Dandy-Walker malformation, Dandy-Walker variant, and mega-cisterna magna (MCM) seem to represent a continuum of developmental anomalies of the posterior fossa. Here we describe the natural clinical history and the radiological features of a family with autosomal or X-linked dominant inheritance of MCM and hydrocephalus of variable severity. The affected family members demonstrate similar structural brain abnormalities including midline cyst, colpocephaly, MCM with a large posterior fossa and minimal vermian hypoplasia. The cognitive development of the affected individuals is normal. L1CAM and FOXC1 gene involvement in the pathogenesis of the disease in this family was excluded. The rare possibility of autosomal dominant or X-linked dominant inheritance and variable penetrance and expressivity must always be considered in genetic counseling of families with hereditary hydrocephalus.     

Immunofluorescence analysis of neutrophil nonmuscle myosin heavy chain-A in MYH9 disorders: association of subcellular localization with MYH9 mutations

The autosomal dominant macrothrombocytopenia with leukocyte inclusions, May-Hegglin anomaly, Sebastian syndrome, and Fechtner syndrome, are rare human disorders characterized by a triad of giant platelets, thrombocytopenia, and characteristic D?hle body-like cytoplasmic inclusions in granulocytes. Epstein syndrome is another autosomal dominant macrothrombocytopenia associated with Alport syndrome but without leukocyte inclusions. These disorders are caused by mutations in the same gene, the MYH9, which encodes the nonmuscle myosin heavy chain-A (NMMHCA). The term, MYH9 disorders, has been proposed, but the clinicopathologic basis of MYH9 mutations has been poorly investigated. In this study, a total of 24 cases with MYH9 disorders and suspected cases were subjected to immunofluorescence analysis by a polyclonal antibody against human platelet NMMHCA. Abnormal subcellular localization of NMMHCA was observed in every neutrophil from individuals with MYH9 mutations. Comparison with May-Grünwald-Giemsa staining revealed that the NMMHCA always coexisted with the neutrophil inclusion bodies, suggesting that NMMHCA is associated with such bodies. In three cases, neutrophil inclusions were not detected on conventional May-Grünwald-Giemsa-stained blood smears but immunofluorescence analysis revealed the abnormal NMMHCA localization. In contrast, cases with Epstein syndrome and the isolated macrothrombocytopenia with normal NMMHCA localization had no MYH9 mutations. An antibody that recognizes the C-terminal 12 mer peptides showed similar immunoreactivity from the patients heterozygous for truncated mutations that abolished the C-terminal epitope, suggesting that normal NMMHCA dimerizes with abnormal NMMHCA to form inclusion bodies. We further propose that the localization pattern can be classified into three groups according to the number, size, and shape of the fluorescence-labeled NMMHCA granule. Immunofluorescence analysis of neutrophil NMMHCA is useful as a screening test for the clear hematopathologic classification of MYH9 disorders.     

Protein‐elongating mutations in MYH11 are implicated in a dominantly inherited smooth muscle dysmotility syndrome with severe esophageal,gastric, and intestinal disease

Gastrointestinal motility disorders include a spectrum of mild to severe clinical phenotypes that are caused by smooth muscle dysfunction. We investigated the genetic etiology of severe esophageal, gastric, and colonic dysmotility in two unrelated families with autosomal dominant disease presentation. Using exome sequencing, we identified a 2 base pair insertion at the end of the myosin heavy chain 11 (MYH11) gene in all affected members of Family 1 [NM_001040113:c.5819_5820insCA(p.Gln1941Asnfs*91)] and a 1 base pair deletion at the same genetic locus in Proband 2 [NM_001040113:c.5819del(p.Pro1940Hisfs*91)]. Both variants are predicted to result in a similarly elongated protein product. Heterozygous dominant negative MYH11 pathogenic variants have been associated with thoracic aortic aneurysm and dissection while biallelic null alleles have been associated with megacystis microcolon intestinal hypoperistalsis syndrome. This report highlights heterozygous protein‐elongating MYH11 variants affecting the SM2 isoforms of MYH11 as a cause for severe gastrointestinal dysmotility, and we hypothesize that the mechanistic pathogenesis of this disease, dominant hypercontractile loss‐of‐function, is distinct from those implicated in other diseases involving MYH11 dysfunction.     

Mutations and sequence variation in the human myosin heavy chain IIa gene (MYH2)

We recently described a new autosomal dominant myopathy associated with a missense mutation in the myosin heavy chain (MyHC) IIa gene (MYH2). In this study, we performed mutation analysis of MYH2 in eight Swedish patients with familial myopathy of unknown cause. In two of the eight index cases, we identified novel heterozygous missense mutations in MYH2, one in each case: V970I and L1061V. The mutations were located in subfragment 2 of the MyHC and they changed highly conserved residues. Most family members carrying the mutations had signs and symptoms consisting mainly of mild muscle weakness and myalgia. In addition, we analyzed the extent and distribution of nucleotide variation in MYH2 in 50 blood donors, who served as controls, by the complete sequencing of all 38 exons comprising the coding region. We identified only six polymorphic sites, five of which were synonymous polymorphisms. One variant, which occurred at an allele frequency of 0.01, was identical to the L1061V that was also found in one of the families with myopathy. The results of the analysis of normal variation indicate that there is strong selective pressure against mutations in MYH2. On the basis of these results, we suggest that MyHC genes should be regarded as candidate genes in cases of hereditary myopathies of unknown etiology.