Identification of a novel frameshift mutation in PITX2 gene in a Chinese family with Axenfeld-Rieger syndrome  

作　　者：Hou-fa YIN Xiao-yun FANG Chong-fei JIN Jin-fu YIN Jin-yu LI Su-juan ZHAO Qi MIAO Feng-wei SONG 

机构地区：[1]Eye Center, the Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou 310009, China [2]Zhejiang Provincial Key Lab of Ophthalmology, Hangzhou 310009, China

出　　处：《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》2014年第1期43-50,共8页浙江大学学报（英文版）B辑（生物医学与生物技术）

基　　金：Project supported by the Qianjiang Talents Project of Zhejiang Province(No.2010R10067);the Zhejiang Key Innovation Team Project of China(No.2009R50039);the Zhejiang Key Laboratory Foundation of China(No.2011E10006)

摘　　要：Objective： Axenfeld-Rieger syndrome （ARS） is phenotypically and genetically heterogeneous. In this study we identified the underlying genetic defect in a Chinese family with ARS. Methods： A detailed family history and clinical data were recorded. The ocular phenotype was documented using slit-lamp photography and systemic anomalies were also documented where available. The genomic DNA was extracted from peripheral blood leukocytes. All coding exons and intron-exon junctions of paired-like homeodomain transcription factor 2 （PITX2） gene and the forkhead box C1 （FOXC1） gene were amplified by polymerase chain reaction （PCR） and screened for mutation by direct DNA sequencing. Variations detected in exon 5 of PITX2 were further evaluated with cloning sequencing. The exon 5 of PITX2 was also sequenced in 100 healthy controls, unrelated to the family, for comparison. Structural models of the wild type and mutant homeodomain of PITX2 were investigated by SWISS-MODEL. Results： Affected individuals exhibited variable ocular phenotypes, whereas the systemic anomalies were similar. After direct sequencing and cloning sequencing, a heterozygous deletion/insertion mutation c. 198_201delinsTTTCT （p.M661fs＊133） was revealed in exon 5 of PITX2. This mutation co-segregated with all affected individuals in the family and was not found either in unaffected family members or in 100 unrelated controls. Conclusions： We detected a novel frameshift mutation p.M661fs＊133 in PITX2 in a Chinese family with ARS. Although PITX2 mutations and polymorphisms have been re- ported from various ethnic groups, we report for the first time the identification of a novel deletion/insertion mutation that causes frameshift mutation in the homeodomain of PITX2 protein.研究目的:对1个Axenfeld-Rieger综合征家系的临床特点及基因突变进行研究,探索Axenfeld-Rieger综合征发病的遗传机制。研究方法:对该Axenfeld-Rieger综合征家系进行全面临床检查,对家系成员应用聚合酶链反应(PCR)扩增PITX2基因和FOXC1基因的所有外显子及相邻内含子,对其产物进行直接测序并对PITX2基因第5个外显子进行克隆测序。选取100名健康者作为对照组,应用PCR扩增PITX2基因第5个外显子并进行直接测序。应用SWISS-MODEL软件对野生型和突变型的PITX2蛋白同源域进行建模分析。重要结论:该Axenfeld-Rieger综合征家系的眼部表型多样,但是各患者的全身系统异常却呈现一致性(见图2;表1)。基因测序结果显示先证者及其他患者均具有PITX2基因杂合突变c.198_201delins TTTCT(p.M66Ifs*133)。尽管PITX2基因突变引起Axenfeld-Rieger综合征已经被广泛证实,但是PITX2基因缺失/插入移码突变引起的Axenfeld-Rieger综合征仅被报道过一次,我们的研究首次在中国人群中揭示了这种罕见的突变方式。

关 键 词：Axenfeld-Rieger syndrome PITX2 gene FOXC1 gene Frameshift mutation HOMEODOMAIN 

分 类 号：R774.1[医药卫生—眼科]