我国人睑裂狭小综合征患者FOXL2基因突变检测

Mutation analysis of FOXL2 in Chinese patients with blepharophimosis-ptosis-epicanthus inversus syndrome

目的研究分析我国人睑裂狭小综合征(BPES)两家系及6例散发病例的基因突变。方法选取染色体3q区域5个微卫星位点D3S3696、D3S1549、D3S3586、D3S1764和D3S1744进行家系连锁分析,应用聚合酶链反应(PCR)和DNA测序技术对提示连锁的染色体区域内候选基因FOXL2进行突变筛查。结果家系连锁分析,将致病基因定位在3q23区D3S3696至D3S1744之间9.88cM范围,其中位点D3S1549、D3S3586的LOD最大值为2.11(θ=0.00),D3S1764为1.51(θ=0.00);对FOXL2基因突变筛查发现,2例散发患者有909～938dup30重复突变,1例散发患者有1041～1042insC移码突变,但两个家系中无突变。结论两个家系与3q23区域的D3S1549、D3S3586和D3S1764位点存在连锁。首次在散发患者中发现两种FOXL2基因突变,其中909～938dup30突变被认为是BPES综合征FOXL2基因两大突变热点之一。尚未发现突变的家系,其致病机制可能与FOXL2基因周围的位置效应,或是与提示连锁的3q23区域内其他基因相关。

Objective To identify the genetic mutation in two Chinese families and 6 sporadic patients with belpharophimesis-ptosis-epicanthus inversus syndrome （BPES）. Methods Polymorphisms of 5 satellite markers on 3q were analyzed and linkage analysis was performed using linkage software （MLINK） in all cases of two families. FOXL2 gene fragments were amplified by PCR and mutation was determined by sequencing DNA fragments in all patients. Results The BPES locus in the pedigrees was mapped to 3q23, a 9, 88 cM interval between markers D3S3696 and D3S1744. The maximum lod scores were 2. 11 （ θ =0.00） at D3S1549 and D3S3586 and 1.51 （θ= 0. 00 ） at D3S1764. By direct sequencing FOXL2 gene, two sporadic cases had a 30-bp in frame duplication 909-938 dup 30 and one sporadic case showed a nucleotide insertion 1041-1042 ins C. However, it was unable to find any causal mutation of FOXL2 in two families with BPES. Conclusions The gene responsible for BPES in two Chinese families was linked to D3S1549, D3S3586 and D3S1764. This is the first reported mutations of FOXL2（909-938 dup 30 and 1041-1042 ins C） in Chinese sporadic cases. One of the mutations, in-frame 30-bp duplication （909-938 dup 30 ）, is one of the most common mutation hotspots in the coding region of FOXL2. In BPES families without FOXL2 mutation, it cannot be excluded that the disorder is caused by a position effect in the surrounding region of FOXL2 gene or by other genes located at 3q23. （Chin J Ophthalmol, 2006,42 ： 409-414）