目的 探索包含青少年起病的成人型糖尿病(maturity-onset diabetes of the young,MODY)患者的2型糖尿病家族中可能存在的MODY基因的致病突变。方法 选择MODY基因中突变率最高的葡萄糖激酶(GCK,MODY2)和肝细胞核因子1α(HNF-1α,MODY3)基因的微卫星多态遗传标志在2个包含临床MODY患者的中国人2型糖尿病家系中进行连锁分析,对HNF-1α基因进行全基因外显子的突变筛查-DNA序列直接测定以明确具体的核苷酸突变和所编码的氨基酸的改变。结果 HNF-1α基因标志物在家系50001中MODY3的最大LOD值达到2.38(θ=0.00),家系50002中,MODY3最大LOD值达到3.59(θ=0.00);两家系均未发现与MODY2连锁的依据。DNA直接测序发现在家系50001中所有家族成员外显子7中存在一个杂合多态Ser487Asn(AGC/AAC),该多态在正常人中也可见到;家系50002中NIDDM/MODY个体MODY3基因外显子5编码区存在一个杂合错义突变Tyr322Asn(TAT→AAT)。结论 GCK基因内或附近的基因变异不是本家系糖尿病的主要致病原因;家系50001中,HNF-1α基因的启动子和所有外显子内没有发现明确的致病突变,但不能否定内含子或其他调节区域的变异可能的致病倾向;由于本家系遗传标志D12S86与糖尿病的连锁LOD最大值达到2.38(θ=0.00),所以也不能排除HNF-1α基因附近其他未知?
Objective To detect mutations of the retinitis pigmentosa GTPase regulator (RPGR) gene in two Chinese X-linked retinitis pigmentosa families. Methods Fragments of exons 1-19 of the RPGR gene were amplified with intronic primers, using genomic DNA as template. The polymerase chain reaction (PCR) products were analysed by single-strand conformation polymorphism (SSCP) and direct sequencing. Mutations were identified by comparing DNA sequences of the patients with those of the normal controls.Results Two novel mutations, c1536delC and E332X, were identified in exons 12 and 9 of the RPGR gene in both families. Each mutation was the first mutation found in their respective exons. Both mutations were predicted to cause premature termination, which resulted in truncated proteins without normal functions of the RPGR products.Conclusions Both mutations are the genetic basis of the pathogenesis in the respective families. Our data might be helpful in analysing the function of the RPGR protein.
