小耳脑形染色体大片段变异及相关基因研究

发布时间：2018-05-17 05:09

本文选题：小耳畸形 + 拷贝数分析　；参考：《北京协和医学院》2016年博士论文

【摘要】：研究背景先天性小耳畸形是一种来源于第一二腮弓的发育异常的先天性出生缺陷,发病机制比较复杂。大量研究显示遗传因素在小耳畸形发病中具有重要作用：(1)同卵双生子共同患病率高于异卵双生子；(2)家系中患者遗传症状的不完全外显性；(3)有家族史者占3-34%,远高于小耳畸形占正常人群的比例；(4)在小耳畸形相关的综合征中发现了基因或染色体异常；(5)诱导特定基因突变可以导致小鼠小耳畸形发生。由此可见,鉴定小耳畸形遗传致病位点是明确小耳畸形病因研究的核心。研究目的先天性小耳畸形遗传学病因包括染色体水平的变异和基因水平的变异。本研究利用单核苷酸多态性芯片在全基因组范围内对小耳畸形患者进行拷贝数变化(CN)分析,筛选可能与先天性小耳畸形有关的染色体大片段变异,并根据变异类型对累及的相关基因进行分析。研究方法采用病例对照方法研究小耳畸形患者进行染色体变异,病例组包括942例小耳畸形患者,对照组为1802例正常人群组。具体方法如下：1.小耳畸形患者染色体大片段变异分析。所有样本DNA采用Illumina公司的Omni ZhongHua Human基因芯片进行全基因组范围分型,运用CNV partition进行基因组拷贝数分析。(1)分析CN的变化：正常二倍体CN=2,拷贝数增加表示该片段染色体的局部重复,拷贝数减小的片段代表染色体的局部缺失；(2)结合CN变化判断畸变发生的位置及片段长度；(3)判断染色体变异类型：分为染色体数目的变异及染色体结构的变异。2.小耳畸形患者染色体结构变异累及基因分析。(1)染色体片段发生部分缺失：查找缺失片段内功能基因的检索及定位；(2)染色体片段发生部分重复：基因的剂量效应和基因的位置效应与先天性小耳畸形的潜在关系。3.小耳畸形相关的染色体数目变异及分析。研究结果1.先天性小耳畸形患者组共发现染色体大片段变异5例,对照组没有发现阳性结果。对染色体变异在先天性小耳畸形患者和对照组中出现的频率进行确切概率法检验,P=0.0033,表明该差异具有统计学意义。2.其中2例表现为染色体结构变异：病例一为13号、14号染色体长臂部分重复,14号染色体断裂片段内发现同源框基因OTX2,OTX2-AS1,对拷贝数增加的染色体片段进行基因筛选,发现2个与NCC及耳发育相关基因及信号通路基因：BMP4及GSC；病例二为5号染色体长臂部分重复,染色体断裂片段内未发现小耳畸形相关的基因,对拷贝数增加的片段内进行检索,发现FGF信号通路相关基因FGF18,FGFR4,FGFl和BMP信号通路相关基因FST, MSX2,SMAD5。3.另外3例表现为染色体数目变异：均表现为X染色体增加。其中一例为XXY综合征；另外两例为X三体综合征。研究结论1.对染色体变异在先天性小耳畸形患者和对照组中出现的频率进行确切概率法检验,显示先天性小耳畸形患者中出现染色体变异的频率高于正常对照,说明染色体变异与先天性小耳畸形的发生存在一定的相关性。2.14号染色体发生畸变的位置累及基因OTX2,可能与该病例小耳畸形的发病有关。3.13、14号染色体重复导致GSC、BMP4基因拷贝数增加,可能与小耳畸形发生有关。4.5号染色体长臂部分重复导致FGF信号通路相关基因FGF18,FGFR4,FGFl和BMP信号通路相关基因FST, MSX2,SMAD5拷贝数增加,可能与小耳畸形发病有关。
[Abstract]:Congenital microtia of the background is a congenital birth defect derived from the developmental abnormality of the first branchial arch . The pathogenesis is complicated . A large number of studies show that the genetic factor plays an important role in the pathogenesis of microtia .
( 2 ) incomplete external dominance of the genetic symptoms of the patients in the family department ;
( 3 ) The family history accounts for 3 - 34 % , which is much higher than that of the normal population .
( 4 ) gene or chromosomal abnormality is found in the syndrome associated with the microtia ;
( 1 ) The genetic etiology of congenital microtia was analyzed by using single nucleotide polymorphism ( CN ) .
( 2 ) judging the position of the distortion and the length of the segment according to the change of the CN ;
( 3 ) judging the type of chromosome variation : the variation of the chromosome number and the variation of the chromosome structure ; 2 . the mutation of the chromosome structure of the patient with the small ear malformation is involved in gene analysis ; ( 1 ) the partial deletion of the chromosomal segment : finding and positioning the functional gene in the deletion fragment ;
( 2 ) Partial repeat of the chromosomal segment : The dose effect of the gene and the potential relationship between the position effect of the gene and the congenital microtia . The results showed that there were 5 cases of chromosome aberration and no positive result in the control group .
Case 2 was repeated in the long arm part of chromosome 5 , and no gene related to microtia was found in the fragment of chromosome fragment . It was found that FGF signaling pathway related genes FGF18 , FGFR4 , FGFl and BMP signaling pathway related genes were found to be related to the expression of FGF18 , FGFR4 , FGFl and BMP signaling pathway . The other three cases showed that the number of chromosomes increased . One of them was XXY syndrome .
Conclusion 1 . The frequency of chromosome variation in the patients with congenital microtia and the control group is higher than that of normal controls . It is suggested that the chromosomal variation has a certain correlation with the occurrence of congenital microtia .
【学位授予单位】：北京协和医学院
【学位级别】：博士
【学位授予年份】：2016
【分类号】：R764.7

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