遗传性多指（趾）畸形及相关基因研究进展

先天性肢异常是人群中较为常见的遗传缺陷，而多指畸形是最常见的先天手畸形。本综述了多指畸形的分类及遗传特点，总结了脊椎动物中肢发育相关基因的研究现状，以及人类多指畸形相关基因的研究进展，并对其研究意义及前景作了展望。     

一个并指(趾)多指(趾)家系的 HOXD13基因突变研究

目的 研究一个中国人并指(趾)多指(趾)(synpolydactyly，SPD)家系的临床特征，检测患者中是否存在同源盒D13基因(homeobox D13，HOXD13）突变。方法 现场调查获取临床资料和19个家系成员的外周血液标本；PCR扩增HOXD13基因突变热点序列进行突变检测；并扩增全编码区用于检测是否存在其他位点的突变；采用2％琼脂糖凝胶电泳初步分析PCR产物，5％聚丙烯酰胺凝胶电泳分离突变片段，纯化后将所有产物直接测序进行基因检测。结果 患者HOXD13基因第1外显子额外插入了编码8个丙氨酸残基的序列，可认为是正常基因中编码第5～12丙氨酸残基序列的异常重复。结论 证实该家族畸形可由HOXD13基因的多聚丙氨酸链扩展突变引起。     

多指 (趾) 致病基因研究进展

多指 (趾) 畸形是最常见肢体畸形之一, 具有遗传性, 分为综合征型和非综合征型两大类型。 非综合征型按照解剖位置可分为轴前、 轴后及中央型多指, 综合征型多指 (趾) 是指除多指表型以外, 还 伴随其他症状。 近些年, 多用连锁分析、 全外显子测序等对相关致病基因的定位及突变进行分析, 并通过 分析突变的基因所表达的蛋白, 了解其对相关信号通路可能产生的影响。 通过总结多指 (趾) 畸形主要致 病基因最新研究及影响肢体前后模式主要通路, 旨在了解多指 (趾) 致病基因的研究方向和热点, 为今后 能在胚胎阶段阻断多指 (趾) 形成的研究提供依据和思路。     

一个中国人并多指(趾)畸形家系中HOXD13基因突变的检测

目的 在一个中国汉族并多指(趾)畸形家系中检测HOXD13基因致病突变.方法 通过PCR扩增HOXD13基因外显子序列,对产物进行直接测序及TA克隆测序寻找致病突变.结果 在患者中发现HOXD13基因外显子1的5'末端丙氨酸重复区内,具有27bp的不完全三核苷酸重复的插入突变,使其多聚丙氨酸链延长了9个丙氨酸残基.结论 HOXD13基因内9个丙氨酸残基的延展突变为该家系的致病突变.     

一个中国人并多指(趾)畸形家系中HOXD13基因突变的检测

目的 在一个中国汉族并多指(趾)畸形家系中检测HOXD13基因致病突变.方法 通过PCR扩增HOXD13基因外显子序列,对产物进行直接测序及TA克隆测序寻找致病突变.结果 在患者中发现HOXD13基因外显子1的5'末端丙氨酸重复区内,具有27bp的不完全三核苷酸重复的插入突变,使其多聚丙氨酸链延长了9个丙氨酸残基.结论 HOXD13基因内9个丙氨酸残基的延展突变为该家系的致病突变.     

一个中国人并多指(趾)畸形家系中HOXD13基因突变的检测

目的 在一个中国汉族并多指(趾)畸形家系中检测HOXD13基因致病突变.方法 通过PCR扩增HOXD13基因外显子序列,对产物进行直接测序及TA克隆测序寻找致病突变.结果 在患者中发现HOXD13基因外显子1的5'末端丙氨酸重复区内,具有27bp的不完全三核苷酸重复的插入突变,使其多聚丙氨酸链延长了9个丙氨酸残基.结论 HOXD13基因内9个丙氨酸残基的延展突变为该家系的致病突变.     

一个中国人并多指(趾)畸形家系中HOXD13基因突变的检测

目的 在一个中国汉族并多指(趾)畸形家系中检测HOXD13基因致病突变.方法 通过PCR扩增HOXD13基因外显子序列,对产物进行直接测序及TA克隆测序寻找致病突变.结果 在患者中发现HOXD13基因外显子1的5'末端丙氨酸重复区内,具有27bp的不完全三核苷酸重复的插入突变,使其多聚丙氨酸链延长了9个丙氨酸残基.结论 HOXD13基因内9个丙氨酸残基的延展突变为该家系的致病突变.     

一个中国人并多指(趾)畸形家系中HOXD13基因突变的检测

目的 在一个中国汉族并多指(趾)畸形家系中检测HOXD13基因致病突变.方法 通过PCR扩增HOXD13基因外显子序列,对产物进行直接测序及TA克隆测序寻找致病突变.结果 在患者中发现HOXD13基因外显子1的5'末端丙氨酸重复区内,具有27bp的不完全三核苷酸重复的插入突变,使其多聚丙氨酸链延长了9个丙氨酸残基.结论 HOXD13基因内9个丙氨酸残基的延展突变为该家系的致病突变.     

一个中国人并多指(趾)畸形家系中HOXD13基因突变的检测

目的 在一个中国汉族并多指(趾)畸形家系中检测HOXD13基因致病突变.方法 通过PCR扩增HOXD13基因外显子序列,对产物进行直接测序及TA克隆测序寻找致病突变.结果 在患者中发现HOXD13基因外显子1的5'末端丙氨酸重复区内,具有27bp的不完全三核苷酸重复的插入突变,使其多聚丙氨酸链延长了9个丙氨酸残基.结论 HOXD13基因内9个丙氨酸残基的延展突变为该家系的致病突变.     

Preaxial polydactyly type 4: variability in a large kindred

A five generation family with type 4 preaxial polydactyly is reported. The 21 affected individuals demonstrated variability in expression without apparent sex influence and penetrance which was complete. The deformities were more severe in the feet than the hands. Anteroposterior flatness of the thumbs was the only manifestation of the trait in the hands of several affected family members.     

一个轴前多指畸形家系的基因变异分析CSCD

目的对1个轴前多指畸形家系进行基因变异分析,明确其可能的致病原因。方法提取先证者及其父母外周血DNA,采用trio全外显子组测序法检测疾病相关基因,筛选出可疑致病基因,并在家系其他成员中进行Sanger测序验证。结果基因测序结果显示家系中6例患者的LMBR1基因均存在c.423+4909(IVS5)C>T杂合变异。表型正常家系成员未检测到该变异。根据美国医学遗传学与基因组学学会遗传变异分类标准与指南,LMBR1基因c.423+4909(IVS5)C>T变异被判断为致病性(PM1+PM2+PP1-S(PS)+PP4+PP5)。结论LMBR1基因第c.423+4909C>T变异可能为该家系患者的致病原因。     

Mutation analysis of a large Chinese pedigree with congenital preaxial polydactyly

Mutations in the long-range limb-specific cis-regulator (ZRS) could cause ectopic shh gene expression and are responsible for preaxial polydactyly (PPD). In this study, we analyzed a large Chinese isolated autosomal dominant PPD pedigree. By fine mapping and haplotype construction, we located the linked region to a 1.7 cM interval between flanking markers D7S2465 and D7S2423 of chromosome 7q36. We directly sequenced the candidate loci in this linked region, including the coding regions of the five genes (HLXB9, LMBR1, NOM1, RNF32 and C7orf13), the regulatory element (ZRS) of shh, the whole intron 5 of LMBR1 which contained the ZRS, and 18 conserved noncoding sequences (CNSs). Interestingly, no pathogenic mutation was identified. By using real-time quantitative PCR (qPCR), we also excluded the ZRS duplication in this pedigree. Our results indicate that, at least, it is not the mutation in a functional gene, CNS region or duplication of ZRS that cause the phenotype of this pedigree. The etiology of this PPD family still remains unclear and the question whether another limb-specific regulatory element of shh gene exists in the noncoding region in this 1.7 cM interval remains open for future research.     

Trisomy 2p syndrome: A fetus with anencephaly and postaxial polydactyly

We report on a male fetus with partial trisomy 2p21-2pter and monosomy 15q26-15qter due to t(2,15)(p21;q26). This fetus had a typical trisomy 2p phenotype including minor facial anomalies, musculoskeletal defects and two unusual findings: polydactyly and anencephaly. The observation of anencephaly adds support to the theory that genetic material mapping to chromosome band 2p24 is involved in neural tube development. In addition, we propose that a gene on 2p23 may play a role in the morphogenetic patterning of hands and feet. Am. J. Med. Genet. 87:45–48, 1999. © 1999 Wiley-Liss, Inc.     

Lack of evidence of a major gene acting on postaxial polydactyly in South America

Data on polydactyly were obtained from two large samples: the Latin American Collaborative Study of Congenital Malformations (ECLAMC), and from a migrant Northeastern Brazilian population of rural origin (Hospedaria). ECLAMC is a case-control clinical epidemiological program comprising 10,035 individuals distributed among 2,030 segregating nuclear families. Hospedaria data consisted of 6,586 examined individuals belonging to 1,040 nuclear families. Using complex segregation analysis methodology we found no evidence of two loci (a major gene and a modifier locus) acting on postaxial polydactyly in the present study. Very high heritability values (in a classical multifactorial model) of postaxial polydactyly were detected, for several sets of analyses in ECLAMC and in Hospedaria. For the whole ECLAMC sample there is a peculiar suggestion of a major recessive gene effect responsible for the trait; however, no comparison with a model involving transmission probabilities (τ) was possible in this highly heterogeneous sample. If the whole ECLAMC sample is divided in subsamples, according to Black admixture proportions, the same multifactorial picture emerges. Two different inheritance patterns were verified for hand (HP) and foot (FP) postaxial polydactyly: For HP there is evidence of a non-Mendelian transmission mechanism, while for FP the parental/sib transmission appears to be due only to multifactorial causes. Am. J. Med. Genet. 80:466–472, 1998. © 1998 Wiley-Liss, Inc.     

Resolution of fluorescence in-situ hybridization mapping on rice mitotic prometaphase chromosomes, meiotic pachytene chromosomes and extended DNA fibers

Fluorescence in-situ hybridization (FISH) is a quick and affordable approach to map DNA sequences to specific chromosomal regions. Although FISH is one of the most important physical mapping techniques, research on the resolution of FISH on different cytological targets is scarce in plants. In this study, we report the resolution of FISH mapping on mitotic prometaphase chromosomes, meiotic pachytene chromosomes and extended DNA fibers in rice. A majority of the FISH signals derived from bacterial artificial chromosome (BAC) clones separated by approximately 1 Mb of DNA cannot be resolved on mitotic prometaphase chromosomes. In contrast, the relative positions of closely linked or even partially overlapping BAC clones can be resolved on a euchromatic region of rice chromosome 10 at the early pachytene stage. The resolution of pachytene FISH is dependent on early or late pachytene stages and also on the location of the DNA probes in the euchromatic or heterochromatic regions. We calibrated the fiber-FISH technique in rice using seven sequenced BAC clones. The average DNA extension was 3.2 kb/μm among the seven BAC clones. Fiber-FISH results derived from a BAC contig that spanned 1 Mb DNA matched remarkably to the sequencing data, demonstrating the high resolution of this technique in cytological mapping. This revised version was published online in July 2006 with corrections to the Cover Date.     

Tetramelic mirror-image polydactyly and a de novo balanced translocation between 2p23.3 and 14q13

We report on a male infant with tetramelic mirror-image polydactyly and a de novo, balanced reciprocal translocation between 2p23.3 and 14q13. This patient suggests that a novel gene, which functions in the morphogenesis of the hands and feet along the anterior-posterior axis, may be located at 2p23.3 or 14q13. Am. J. Med Genet. 68:70–73, 1997 © 1997 Wiley-Liss, Inc.