中国人并多指(趾)畸形家系中HOXD13基因突变及产前诊断  

HOXD13 polyalanine tract expansion in synpolydactyly: mutation detection and prenatal diagnosis in a large Chinese family

作　　者：赵秀丽[1] 孟金萍 孙淼[1] 敖杨[1] 吴爱华 罗会元[1] 张学[1] 

机构地区：[1]中国医学科学院中国协和医科大学基础医学研究所医学遗传学系,医学分子生物学国家重点实验室,北京100005 [2]山东省计划生育科学技术研究所

出　　处：《中华医学遗传学杂志》2005年第1期5-9,共5页Chinese Journal of Medical Genetics

基　　金：国家高技术研究发展计划(2001AA221101和2002BA711A07-09);美国中华医学基金会(CMB)(03-785)~~

摘　　要：目的对中国山东一个并多指(趾),又称型并指(趾),畸形大家系进行致病基因突变的鉴定,确定中国人并多指(趾)畸形家系中是否存在HOXD13基因突变;通过检测突变HOXD13基因对高危胎儿进行产前基因诊断。方法根据家族史、临床体征和手足X线检查进行临床诊断;采集家系成员外周血标本及受检孕妇羊水和绒毛标本,常规提取基因组DNA;设计并合成1对特异引物,通过PCR扩增HOXD13基因第1外显子内多聚丙氨酸链编码序列;PCR扩增片段经琼脂糖凝胶电泳检测,异常扩增片段经TA克隆后测序鉴定;产前诊断中,通过PCR扩增、变性聚丙烯酰胺凝胶电泳和银染检查HOXD13基因内及基因两侧共3个微卫星多态标记进行单体型分析。结果本家系4代54人,患者16人(男6人,女10人);手足共同表现为3/4完全并指伴软组织蹼内多指,4/5并趾伴软组织蹼内多趾;外显率为100%,表现度变异明显。上述表现符合典型常染色体显性并多指(趾)的表型特征。对家系中18人(患者9人)进行HOXD13基因分析,结果显示全部患者多聚丙氨酸链中丙氨酸残基数由正常的15个延长为24个。通过HOXD13基因多聚丙氨酸链延展突变检测和单体型分析,对家系中1女性患者两次怀孕进行产前诊断,发现胎儿均携带突变HOXD13基因。结论首次在中国人典型并多指(趾)Objective Synpolydactyly (SPD, MIM 186000), also known as syndactyly type II, is a dominantly inherited limb malformation with incomplete penetrance and variable expressivity. Polyalanine tract expansion in HOXD13 has been shown to be the disease-causing mutation in SPD. The present study was designed to identify mutation in HOXD13 and to provide prenatal diagnosis, in a large Chinese SPD family consisting of 54 individuals. Methods The proband and 4 other affected individuals in the family were evaluated physically and radiologically to ascertain the SPD phenotype. Genomic DNA was extracted from peripheral blood samples obtained from 18 family members (9 affected and 9 unaffected), and from amniotic fluid and chorionic villus samples obtained from the proband during her two consecutive pregnancies. With the use of a pair of specific primers, a fragment of 161bp was amplified by polymerase chain reaction (PCR) to cover the imperfect GCN triplet repeat sequence in exon 1 of HOXD13 encoding the 15-residue polyalanine ~tract. The PCR products were detected by agarose gel ~electrophoresis, and sequenced after cloning into pMD18T ~vector. To confirm prenatal ~diagnosis, haplotype analysis was also performed by allele-typing three microsatellite markers, including the intronic CA repeats in HOXD13. Results Digital and radiographic findings indicated a typical SPD phenotype in the family. These included 3/4 finger syndactyly and 4/5 toe syndactyly with an extra digit in the syndactylous web. Unilateral finger syndactyly in the proband, unilateral toe syndactyly in 2 individuals, bilateral brachydactyly of the fifth toes in 1 individual, and clinodactyly of the fifth fingers in 4 individuals were also observed, indicating variable expressivity. Gel electrophoresis of the PCR products showed an additional longer fragment in all 9 affected individuals but not in the unaffected ones. Sequence analysis of the longer fragment revealed a 9-alanine expansion. The expansion was detectable in DNA from the amniotic fluid and chori

关 键 词：家系 基因突变 产前诊断 患者 畸形 胎儿 单体型 PCR扩增 银染 变性聚丙烯酰胺凝胶电泳 

分 类 号：R394[医药卫生—医学遗传学]