先天性软骨发育不全成纤维细胞生长因子受体3基因1138位核苷酸点突变的检测

目的 验证成纤维细胞生长因子受体3(fibroblast growth factor receptor 3，FGFR3)跨膜区1138位核苷酸为先天性软骨发育不全突变热点及用变性梯度电泳方法筛查的效果。方法 对17例临床诊断为先天性软骨发育不全患者进行基因组DNA聚合酶链反应－限制性酶切片段长度多态性（polymerase chain reaction-restriction fragment length polymorphism,PCR-RFLP)分析，并用变性梯度凝胶电泳（denaturing gradient gel electrophoresis,DGGE)进行其它突变位点的筛查。结果 17例患者中14例RFLP检测显示能被Sfc I酶切，提示存在1138位核苷酸G→A的转换，且均为杂合子。17例用Msp I酶切均阴性，提示无G→C的颠换。DGGE方法的筛查中，酶切阳性的14例标本均显示存在杂合型突变。3例PCR－RFLP检测阴性的标本未显示突变位点，提示在该扩增区域确实不存在突变位点。结论 FGFR3跨膜区1138核苷酸G→A的突变是软骨发育不全的主要发病机理，DGGE可作为筛查某一区域基因突变的敏感而可靠的检测手段，尤其是对杂合子的检测。

Detection of fibroblast growth factor receptor 3 gene mutation at nucleotide 1138 site in congenital achondroplasia patients

OBJETIVE: To investigate the mutation at the transmembrane domain of fibroblast growth factor receptor 3 (FGFR3) nucleotide 1138 site for identifying the major pathologic mechanism of achondroplasia (ACH) and to evaluate the efficacy of denaturing gradient gel electrophoresis(DGGE) method for screening the point mutations. METHODS: The genomic DNA from 17 clinically diagnosed ACH patients where analysed by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) with Sfc I and Msp I restriction endonucleases and by PCR-DGGE technique for screening. RESULTS: G to A transition mutation at nucleotide 1138 was detected in 14/17 of the ACH patients as heterozygotes by PCR-RFLP with Sfc I digestion. No 1138 G to C transition was detected by Msp I digestion. All of the 14 samples with G to A mutation were also found to be positive for point mutation by PCR-DGGE. No mutation was detected in 3 negative samples by PCR-RFLP, implying that there was actually no point mutation in this amplified region. CONCLUSION: Nucleotide 1138 in transmembrane domain of FGFR3 gene is the hot point for mutation in ACH and hence its major pathologic cause. PCR-DGGE is a sensitive and reliable technique for point mutation screening, especially for the heterozygotes.