眼皮肤白化病研究的新途径及TYR基因2种新突变的分析

A new method for oculocutaneous albinism typing and analysis of two novel mutations in TYR gene

目的:探讨自眼皮肤白化病(OCA)患者毛发提取DNA对OCA分型研究的可行性及TYR基因2种新突变的致病性。方法:应用毛发压片镜检,PCR扩增毛发DNA中OCA相关基因各外显子、外显子-内含子交界区及启动子区,直接以序列测定技术分析患者基因突变,明确患者的基因型。对于发现的新突变,采用突变等位基因频率等方法对其进行深入研究。结果:3个家系的先证者均为1型OCA。家系1的先证者为c.715C>T(p.R239W)和c.929insC(p.P310PfsX7)突变的复合杂合子;家系2的先证者为c.896G>A(p.R299H)的纯合子;家系3的先证者为c.1362+3A>T和c.650G>C(p.R217P)突变的复合杂合子。其中,c.1362+3A>T和c.650G>C(p.R217P)突变为至今尚未报道的新突变,通过对新突变进行分析,推测其极可能为病理性新突变。结论:本实验成功证实从毛发中提取DNA的方法对OCA分型研究的可行性,同时确定了2种致病性新突变,为今后OCA研究开拓了新的思路和途径。

AIM： To establish a new approach to oculocutaneous albinism（OCA） classification using the DNA extracted from hair bulb and identify two novel pathogenic mutations in TYR gene.METHODS： The morphological changes of hair bulb tissues were observed under optical microscope.The target DNA fragments of axons,promoter and exon-intron adjacent were amplified by PCR,followed by direct DNA sequencing.The novel mutations were further analyzed using mutant allele frequency method.RESULTS： The 3 probands were all tyrosinase-related OCA（OCA1）.The proband in family 1 showed as a compound heterozygote with mutants of c.715CT（p.R239W） and c.929ins〉C（p.P310PfsX7）.The proband in family 2 showed as a homozygote with c.896GA（p.R299H）.The proband in family 3 was a compound heterozygote with mutants of c.1362＋3AT and c.650GC（p.R217P）.The mutations of c.1362＋3AT and c.650GC（p.R217P） were novel.The result of mutant allele frequency indicated that the novel mutations were most likely pathological mutations.CONCLUSION： We successfully establish a feasible approach to OCA classification using the DNA extracted from hair bulb,and identify two novel mutations.