一个非综合征手足裂畸形家系的临床调查及遗传学分析

目的分析一先天性手足裂伴并指／趾畸形家系的临床表现，并从分子水平查找致病原因，为罹患家庭提供遗传咨询。方法通过X线检查资料及手足裂外观照片，对家系3代现存3例患者（共4例患者）进行临床分析，对3例患者用常规方法制备外周血淋巴细胞染色体标本，进行G显带核型分析。从7名家系成员（包含3例患者）外周血样品中提取基因组DNA。针对p63基因全部15个外显子及删rJ0b基因5个外显子进行引物设计合成、PCR扩增、回收纯化并测序。结果家系中现存3名患者均表现为双手中央分裂，其中1例患者双足呈楔形裂开，2例患者右足均为第3、4趾并指，皮肤黏连；G显带核型分析未发现染色体畸变；p63基因未检测到突变，删rJ0b基因的外显子5a中发现一个碱基突变c．1058C〉T。结论通过家系内息者临床表型分析，可将该疾病类型确定为非综合征手足裂畸形，且临床症状逐代加重。测序结果提示p63基因和删rJ0b基因关键区域内的点突变都不是引起该家系手足裂畸形的原因。     

中国汉族单纯型发作性运动诱发性运动障碍家系的致病基因定位研究

目的 在1个中国汉族单纯型发作性运动诱发性运动障碍(paroxyamal kinesigenic dykinesia,PKD)大家系中定位其致病基因所在区域.方法 用商业化的ABI微卫星试剂盒进行全基因组扫描,用Linkage和Genehunter等软件对基因分型的结果 进行参数和非参数连锁分析,并在最可能的阳性区域内进一步选择微卫星位点进行精细定位和单倍型分析.验证全基因组扫描结果 并缩小单纯型PKD家系的新位点区域.结果 全基因组扫描在D3S1580处得到最大的两点LOD值1.75(θ=0);精细定位在D3S3669处得到最大的LOD值2.82(θ=0),NPL值9.83.单倍型分析将致病基因定位于D3S1314和D3S1265之间约10.2 cM大小的区域.结论 该单纯型PKD家系的致病基因定位于3q28-29的D3S1314和D3S1265之间10.2 cM区域,是一个新的PKD致病基因位点.     

全基因组扫描定位一个先天性全白内障家系的致病基因

目的定位一个先天性全白内障家系的致病基因。方法收集一个先天性全白内障家系中10个成员的外周血样本,提取基因组DNA。应用ABI-MD10试剂盒中的常染色体382个微卫星位点,对此家系进行全基因组扫描。MLINK软件进行两点连锁分析。结果发现在D13S263位点处提示存在连锁(最大LOD=1.20,重组率θ=0),进一步检测该位点附近若干其它的微卫星标记,经连锁分析其致病基因被定位到D13S175和D13S156之间的大约53.9厘摩(cM)区域上。结论该家系致病基因位点被定位到13号染色体的13q12.11-q22.1之间的大约53.9cM区域上。此研究为探讨遗传性全白内障的发病机制提供了有价值的信息,并为该家系今后开展产前诊断奠定了基础。     

先天性视网膜脉络膜缺损一家系基因连锁定位分析

目的 对一个连续3代常染色体显性遗传性先天性视网膜脉络膜缺损(autosomal dominant congenital retinaochoroidal coloboma)家系进行致病基因的连锁定位分析.方法 对家系所有成员进行详细的临床检查,排除其他系统疾患.提取家系成员外周血DNA,选取位于全部染色体上的398对微卫星标记物,进行全基因组扫描.经ABI3130型遗传分析仪,Genescan收集数据,Genotyper进行基因分型,Linkage软件计算两点Lod值.结果 在2号染色体长臂上的微卫星标记物D2S2382取得最大的Lod值,其Lod值为3.01.进一步在D2S2382附近选择微卫星标记物,进行连锁分析,发现微卫星标记物D2S2382-D2S301-D2S2244-D2S163与家系中所有患者疾病表型共分离.结论 将一个常染色体显性遗传性先天性视网膜脉络膜缺损家系的致病基因定位于2q34-2q35之间的3.80 cM范围内.     

先天性视网膜脉络膜缺损一家系基因连锁定位分析

目的 对一个连续3代常染色体显性遗传性先天性视网膜脉络膜缺损(autosomal dominant congenital retinaochoroidal coloboma)家系进行致病基因的连锁定位分析.方法 对家系所有成员进行详细的临床检查,排除其他系统疾患.提取家系成员外周血DNA,选取位于全部染色体上的398对微卫星标记物,进行全基因组扫描.经ABI3130型遗传分析仪,Genescan收集数据,Genotyper进行基因分型,Linkage软件计算两点Lod值.结果 在2号染色体长臂上的微卫星标记物D2S2382取得最大的Lod值,其Lod值为3.01.进一步在D2S2382附近选择微卫星标记物,进行连锁分析,发现微卫星标记物D2S2382-D2S301-D2S2244-D2S163与家系中所有患者疾病表型共分离.结论 将一个常染色体显性遗传性先天性视网膜脉络膜缺损家系的致病基因定位于2q34-2q35之间的3.80 cM范围内.     

先天性视网膜脉络膜缺损一家系基因连锁定位分析

目的 对一个连续3代常染色体显性遗传性先天性视网膜脉络膜缺损(autosomal dominant congenital retinaochoroidal coloboma)家系进行致病基因的连锁定位分析.方法 对家系所有成员进行详细的临床检查,排除其他系统疾患.提取家系成员外周血DNA,选取位于全部染色体上的398对微卫星标记物,进行全基因组扫描.经ABI3130型遗传分析仪,Genescan收集数据,Genotyper进行基因分型,Linkage软件计算两点Lod值.结果 在2号染色体长臂上的微卫星标记物D2S2382取得最大的Lod值,其Lod值为3.01.进一步在D2S2382附近选择微卫星标记物,进行连锁分析,发现微卫星标记物D2S2382-D2S301-D2S2244-D2S163与家系中所有患者疾病表型共分离.结论 将一个常染色体显性遗传性先天性视网膜脉络膜缺损家系的致病基因定位于2q34-2q35之间的3.80 cM范围内.     

先天性视网膜脉络膜缺损一家系基因连锁定位分析

目的 对一个连续3代常染色体显性遗传性先天性视网膜脉络膜缺损(autosomal dominant congenital retinaochoroidal coloboma)家系进行致病基因的连锁定位分析.方法 对家系所有成员进行详细的临床检查,排除其他系统疾患.提取家系成员外周血DNA,选取位于全部染色体上的398对微卫星标记物,进行全基因组扫描.经ABI3130型遗传分析仪,Genescan收集数据,Genotyper进行基因分型,Linkage软件计算两点Lod值.结果 在2号染色体长臂上的微卫星标记物D2S2382取得最大的Lod值,其Lod值为3.01.进一步在D2S2382附近选择微卫星标记物,进行连锁分析,发现微卫星标记物D2S2382-D2S301-D2S2244-D2S163与家系中所有患者疾病表型共分离.结论 将一个常染色体显性遗传性先天性视网膜脉络膜缺损家系的致病基因定位于2q34-2q35之间的3.80 cM范围内.     

先天性视网膜脉络膜缺损一家系基因连锁定位分析

目的 对一个连续3代常染色体显性遗传性先天性视网膜脉络膜缺损(autosomal dominant congenital retinaochoroidal coloboma)家系进行致病基因的连锁定位分析.方法 对家系所有成员进行详细的临床检查,排除其他系统疾患.提取家系成员外周血DNA,选取位于全部染色体上的398对微卫星标记物,进行全基因组扫描.经ABI3130型遗传分析仪,Genescan收集数据,Genotyper进行基因分型,Linkage软件计算两点Lod值.结果 在2号染色体长臂上的微卫星标记物D2S2382取得最大的Lod值,其Lod值为3.01.进一步在D2S2382附近选择微卫星标记物,进行连锁分析,发现微卫星标记物D2S2382-D2S301-D2S2244-D2S163与家系中所有患者疾病表型共分离.结论 将一个常染色体显性遗传性先天性视网膜脉络膜缺损家系的致病基因定位于2q34-2q35之间的3.80 cM范围内.     

先天性视网膜脉络膜缺损一家系基因连锁定位分析

目的 对一个连续3代常染色体显性遗传性先天性视网膜脉络膜缺损(autosomal dominant congenital retinaochoroidal coloboma)家系进行致病基因的连锁定位分析.方法 对家系所有成员进行详细的临床检查,排除其他系统疾患.提取家系成员外周血DNA,选取位于全部染色体上的398对微卫星标记物,进行全基因组扫描.经ABI3130型遗传分析仪,Genescan收集数据,Genotyper进行基因分型,Linkage软件计算两点Lod值.结果 在2号染色体长臂上的微卫星标记物D2S2382取得最大的Lod值,其Lod值为3.01.进一步在D2S2382附近选择微卫星标记物,进行连锁分析,发现微卫星标记物D2S2382-D2S301-D2S2244-D2S163与家系中所有患者疾病表型共分离.结论 将一个常染色体显性遗传性先天性视网膜脉络膜缺损家系的致病基因定位于2q34-2q35之间的3.80 cM范围内.     

先天性视网膜脉络膜缺损一家系基因连锁定位分析

目的 对一个连续3代常染色体显性遗传性先天性视网膜脉络膜缺损(autosomal dominant congenital retinaochoroidal coloboma)家系进行致病基因的连锁定位分析.方法 对家系所有成员进行详细的临床检查,排除其他系统疾患.提取家系成员外周血DNA,选取位于全部染色体上的398对微卫星标记物,进行全基因组扫描.经ABI3130型遗传分析仪,Genescan收集数据,Genotyper进行基因分型,Linkage软件计算两点Lod值.结果 在2号染色体长臂上的微卫星标记物D2S2382取得最大的Lod值,其Lod值为3.01.进一步在D2S2382附近选择微卫星标记物,进行连锁分析,发现微卫星标记物D2S2382-D2S301-D2S2244-D2S163与家系中所有患者疾病表型共分离.结论 将一个常染色体显性遗传性先天性视网膜脉络膜缺损家系的致病基因定位于2q34-2q35之间的3.80 cM范围内.     

A second autosomal split hand/split foot locus maps to chromosome 10q24-q25

Ectrodactyly (split hand/split foot malformation, SHSF) is ahuman limb malformation characterized by absent central digitalrays, deep median cleft, and syndactyly of remaining digits.The disorder is genetically heterogeneous, with at least twoloci thus far determined: an autosomal locus at 7q21 designatedSHFM1 and an X-linked locus at Xq26 designated SHFM2. Cytogeneticanalysis of sporadic SHSF patients and linkage studies in extendedpedigrees both suggest more than one autosomal locus exists.We report a novel SHSF locus suggested by a stillborn infantwith ectrodactyly and other malformations who inherited an unbalancedtranslocation resulting in monosomy 4p15.1–4pter and trisomyfor 10q25.2-qter. To investigate 10q25 as a possible split hand/splitfoot locus, microsatellite markers spanning 52 cM of 10q wereutilized for linkage analysis of a large autosomal dominantSHSF pedigree in which the region encompassing SHFM1 previouslywas excluded as containing the causative mutation. The markerD10S583 was fully informative in the family, giving a maximumLOD score of 4.21 at recombination     

一个先天性手足裂畸形家系的遗传学分析

目的对1个先天性手足裂畸形家系进行遗传学分析,以鉴定致病性变异。方法提取先证者及家系中其他患者的基因组DNA,应用染色体微阵列技术对患者进行全基因组拷贝数变异分析。结果染色体微阵列分析显示先证者和另外3例患者存在染色体10q24.31-q24.32区域约400 kb的片段重复变异,该重复区域包含完整的LBX1、BTRC、POLL及DPCD基因,并含有FBXW4基因的部分外显子。结论染色体10q24.31-q24.32区域的重复与该家系患者疾病表型共分离,基因组拷贝数变异为患者的致病原因。     

Refined mapping of a gene for split hand-split foot malformation (SHFM3) on chromosome 10q25.

Split hand-split foot malformation (SHFM) is a genetically heterogeneous limb developmental defect characterised by the absence of digital rays and syndactyly of the remaining digits. Three disease loci have recently been mapped to chromosomes 7q21 (SHFM1), Xq26 (SHFM2), and 10q25 respectively (SHFM3). We report the mapping of SHFM3 to chromosome 10q25 in two large SHFM families of French ancestry (Zmax for the combined families = 6.62 at theta = 0 for marker AFM249wc5 at locus D10S222). Two recombinant events reduced the critical region to a 9 cM interval (D10S1709-D10S1663) encompassing several candidate genes including a paired box gene PAX2 (Zmax = 5.35 at theta = 0). The fibroblast growth factor 8 (FGF 8), the retinol binding protein (RBP4), the zinc finger protein (ZNF32), and the homeobox genes HMX2 and HOX11 are also good candidates by both their position and their function.     

Clouston hidrotic ectodermal dysplasia (HED): genetic homogeneity, presence of a founder effect in the French Canadian population and fine genetic mapping

HED is an autosomal dominant skin disorder that is particularly common in the French Canadian population of south-west Quebec. We previously mapped the HED gene to the pericentromeric region of chromosome 13q using linkage analysis in eight French Canadian families. In this study, we extend our genetic analysis to include a multiethnic group of 29 families with 10 polymorphic markers spanning 5.1 cM in the candidate region. Two-point linkage analysis strongly suggests absence of genetic heterogeneity in HED in four families of French, Spanish, African and Malaysian origins. Multipoint linkage analysis in all 29 families generated a peak lod score of 53.5 at D13S1835 with a 1 lod unit support interval spanning 1.8 cM. Recombination mapping placed the HED gene in a 2.4 cM region flanked by D13S1828 proximally and D13S1830 distally. We next show evidence for a strong founder effect in families of French Canadian origin thereby representing the first example of a founder disease in the south-west part of the province of Quebec. Significant association was found between HED in these families and all markers analysed (Fisher's exact test, P < 0.001). Complete allelic association was detected at D13S1828, D13S1827, D13S1835, D13S141 and D13S175 (P(excess) = 1) spanning 1.3 cM. A major haplotype including all 10 associated alleles was present on 65% of affected chromosomes. This haplotype most likely represents the founder haplotype that introduced the HED mutation into the French Canadian population. Luria-Delbrück equations and multipoint likelihood linkage disequilibrium analysis positioned the gene at the D13S1828 locus (likely range estimate: 1.75 cM) and 0.58 cM telomeric to this marker (support interval: 3.27 cM) respectively.     

An ancestral core haplotype defines the critical region harbouring the North Carolina macular dystrophy gene (MCDR1).

Autosomal dominant North Carolina macular dystrophy (NCMD) or central areolar pigment epithelial dystrophy (CAPED) is an allelic disorder that maps to an approximately 7.2 cM interval between DNA markers at D6S424 and D6S1671 on 6q14-q16.2. The further refinement of the disease locus has been hindered by the lack of additional recombination events involving the critical region. In this study, we have identified three multigeneration families of German descent who express the NCMD phenotype. Genotyping was carried out with a series of markers spanning approximately 53 cM around the NCMD locus, MCDR1. Genetic linkage between the markers and the disease phenotype in each of the families could be shown. Disease associated haplotypes were constructed and provide evidence for an ancestral founder for the German NCMD families. This haplotype analysis suggests that a 4.0 cM interval flanked by markers at D6S249 and D6S475 harbours the gene causing NCMD, facilitating further positional cloning approaches.     

Localization of a gene responsible for autosomal recessive demyelinating neuropathy with focally folded myelin sheaths to chromosome 11q23 by homozygosity mapping and haplotype sharing

Hereditary motor and sensory neuropathy (HMSN) with focally folded myelin sheaths, or Charcot-Marie-Tooth type 4B (CMT4B), is a distinct clinical entity belonging to the heterogeneous group of autosomal recessive demyelinating neuropathies. We first described a large pedigree with CMT4B, which showed a high consanguinity level and an autosomal recessive pattern of inheritance. Through conventional linkage analysis, we excluded linkage of the locus segregating in this pedigree to any of the known genes responsible for other HMSNs. Using homozygosity mapping and haplotype sharing analysis, we were able to localize the disease gene in a 4 cM interval on chromosome 11q23, between the D11S1332 and D11S917 loci. On the basis of the clinical characteristics of the disease, we propose that this locus corresponds to the CMT4B gene.      

Genomewide linkage scan in a multigeneration Caucasian pedigree identifies a novel locus for keratoconus on chromosome 5q14.3-q21.1.

PURPOSE: Keratoconus is a corneal dystrophy with an incidence of 1 in 2000 and a leading cause for cornea transplantation in Western developed countries. Both clinical observations and segregation analyses suggest a major role for genes in its pathogenesis. It is genetically heterogeneous, most commonly sporadic, but inherited patterns with recessive or dominant modes have also been reported. We studied a four-generation autosomal-dominant pedigree to identify disease loci for keratoconus. METHODS: A two-stage genome-wide scan was applied to 27 family members. First linkage analysis was performed with 343 microsatellite markers along the 22 autosomal chromosomes at approximately 10 cM density. This was followed by fine mapping at approximately 2 cM density, in regions suggestive of linkage. Multipoint linkage analysis was performed using GeneHunter2. RESULTS: Evidence of suggestive linkage from the initial scan was observed at the 82 to 112 cM region of chromosome 5q14.1-q21.3 with a maximum lod score (LOD) of 3.48 (penetrance = 0.5). Fine mapping by testing an additional 11 microsatellite markers at 1 to 3 cM intervals revealed a narrower and higher peak (99-119 cM) with LOD 3.53. By analysis of the recombination of haplotypes, the putative locus of keratoconus was further narrowed to a 6 cM region (8.2 Mbp physical distance) between markers D5S2499 and D5S495. CONCLUSION: These results indicate a promising new locus for keratoconus in this pedigree. Because of the heterogeneous nature of keratoconus, this locus may be specific to familial autosomal-dominant keratoconus. Nevertheless, the identification of this locus may provide new insights into the pathogenesis of keratoconus.     

Search for a shared segment on chromosome 10q26 in patients with bipolar affective disorder or schizophrenia from the Faroe Islands

Previous linkage studies have suggested a new locus for bipolar affective disorder and possibly also for schizophrenia on chromosome 10q26. We searched for allelic association and chromosome segment and haplotype sharing on chromosome 10q26 among distantly related patients with bipolar affective disorder or schizophrenia and controls from the relatively isolated population of the Faroe Islands by investigating 22 microsatellite markers from a 35 cM region. We used a combined approach with both assumption free tests and tests based on genealogical relationships. The 6.5 cM region between D10S1230 and D10S2322, which has been implied in previous linkage analyses, received some support. A search for segment sharing yielded empirical P-values around 0.02 among patients with bipolar affective disorder and around 0.03 for patients with schizophrenia. For both disorders combined allelic association yielded empirical P-values around 0.003 at marker D10S1723. A haplotype data mining approach supported haplotype sharing in this region. In another, more distal, 11.5 cM region between markers D10S214 and D10S505, which has received support in previous linkage studies, increased haplotype sharing in patients with bipolar affective disorder was supported by Fisher's exact test, tests based on genealogy and by haplotype data mining. Our findings yield some support for a risk gene for bipolar affective disorder and possibly also for schizophrenia.     

A split hand-split foot (SHFM3) gene is located at 10Q24→25

The split hand-split foot (SHSF) malformation affects the central rays of the upper and lower limbs. It presents either as an isolated defect or in association with other skeletal or non-skeletal abnormalities. An autosomal SHSF locus (SHSFM1) was previously mapped to 7q22.1. We report the mapping of a second autosomal SHSF locus to 10q24→25. A panel of families was tested with 17 marker loci mapped to the 10q24→25 region. Maximum lod scores of 3.73, 4.33 and 4.33 at a recombination fraction of zero were obtained for the loci D10S198, PAX2 and D10S1239, respectively. An 19 cM critical region could be defined by haplotype analysis and several genes with a potential role in limb morphogenesis are located in this region. Heterogeneity testing indicates the existence of at least one additional autosomal SHSF locus. © 1996 Wiley-Liss, Inc.     

Linkage analysis of a large Swedish kindred provides further support for a susceptibility locus for schizophrenia on chromosome 6p23.

Several reports have indicated genetic linkage between markers on the short arm of chromosome 6 and schizophrenia. However, significant threshold levels were not always achieved, and the chromosomal regions identified are large and different in different families. One way to decrease the problem of heterogeneity is to study a single extended pedigree. Here we report the analysis of a very large, previously undescribed pedigree from northern Sweden that includes 31 affected individuals. We typed 16 markers spanning 40 cM on the short arm of chromosome 6. Linkage analysis was performed only with the affected individuals. Suggestive lod scores (maximum 2.6) were obtained with markers on chromosome 6p23 in a single branch of the large pedigree indicating possible heterogeneity inside the family. A haplotype comprising markers from D6S309 to D6S1578 was found to segregate with the disease. This chromosomal region is included within a segment proposed to contain a susceptibility gene for schizophrenia by many other investigators. Our results thus give further support for a possible localization of a susceptibility locus for schizophrenia in 6p23 and help to narrow the candidate chromosomal region to the segment included between markers D6S309 and D6S1578.