一汉族念珠状发家系Ⅱ型毛发角蛋白基因突变的检测

Detection of Mutation of Type Ⅱ Hair Keratin Gene in a Han Family of Monilethrix

目的检测一个汉族念珠状发家系Ⅱ型毛发角蛋白(hHb)基因的突变情况。方法在取得遗传学研究知情同意书后,采集先证者及其家系成员外周血并提取基因组DNA。运用聚合酶链式反应(PCR)扩增hHb1、hHb3、hHb6外显子1和外显子7,DNA直接测序,然后与GenBank中登记序列进行比对分析。对新发现的单核苷酸多态性(SNPs)进行限制性位点酶切分析加以验证。结果经网上比对分析,该家系患者均未发现已报道的10种hHb致病突变,但发现该家系hHb1的外显子1存在第348位的单个碱基转换(G/A),经限制性位点酶切分析法证实为一个同义cSNPs(第348位G/A,R116R)。结论该家系念珠状发患者的致病基因不同于现已报道的10种hHb致病突变,在他们hHb1外显子1存在一个同义cSNPs。

Objective To investigate the mutation of type Ⅱ human basic hair keratin （hHb/KRTHB） gene in a Han family of monilethrix and accumulate information for further study on pathogenic mechanism of monilethrix. Methods Informed consent for the study was obtained from the proband and her family members. Their peripheral blood samples were drawn for their genomic DNA. Exon 1 and exon 7 of hHbl, hHb3 and hHb6 were amplified by polymerase chain reaction （PCR）. All PCR products were sequenced directly using ABI3730 automated sequencer. These sequences were compared with those in Gen-Bank with BLAST software. At last, digestion with restriction endonuclease and restriction fragment length polymorphism （RFLP） was used to confirm a novel single nucleotide polymorphisms （SNPs）. Results A series of specific PCR products were obtained from all specimens. The 10 missense mutations in hHb which had been reported were not identified in our study pedigree. A SNPs （348 G/A, R116R） was identified in exon 1 of hHbl gene from this family members. It was a novel coding SNPs （cSNPs） confirmed with restriction endonuclease and RFLP. Conclusion There is a pathogenic gene in our study family, which is different from the 10 reported pathogenic mutations in hHb gene; There is a novel synonymous cSNPs identified in the exon 1 of hHbl gene in this family.