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目的 了解CYP2 1基因编码区的常见突变谱和突变热点 ,并分析基因型和表现型的关系。方法 对来自 51个家庭的 52例 2 1 羟化酶缺乏症患者的全长CYP2 1基因分两个片断进行特异性聚合酶链反应 (PCR)扩增 ,在此基础上进行相应的巢式PCR扩增 ,再根据突变的特点分别采用限制性片段长度多态性 (RFLP)和扩增产生酶切位点 (ACRS)的方法 ,检测 6种突变 :P3 0L、I2g(内含子 2的nt 656a/c→g剪切突变 )、E3Δ8nt(外显子 3第 111～ 113密码子的 8bp缺失 )、I172N、V2 81L和Q3 18X。结果 在 10 2个等位基因中 ,除了 2 7个等位基因外都能够确定基因型。最常见的突变为I2g ,其发生频率为 3 1% ,其次为I172N( 2 3 % ) ,Q3 18X( 14 % ) ,V2 81L( 9% ) ,P3 0L( 3 % ) ,E3Δ8nt( 2 % ) ,其中有 2个以上复合突变的等位基因占 6%。失盐型患者最常见的突变为I2g( 4 5 7% )和Q3 18X( 2 6% )。单纯型最常见的突变为I172N( 4 0 7% )和I2g( 18 5% )。结论 本组 52例患者中 73 %的等位基因突变为上述 6种突变 ,以I2g和I172N为突变热点 ,2种突变占 54%。上述结果为进一步的遗传咨询和产前诊断服务提供了有用的信息
Objective To understand the common mutations and hotspots in the coding region of CYP2 1 gene and to analyze the relationship between genotypes and phenotypes. Methods 52 full-length CYP2 1 genes from 51 families of 21 patients with 21-hydroxylase deficiency were amplified by polymerase chain reaction (PCR) amplification in two fragments. Based on this, corresponding nested PCR According to the characteristics of the mutation, restriction fragment length polymorphism (RFLP) and amplified restriction site (ACRS) were used to detect six mutations: P3 0L, I2g (intron 2 nt 656a / c → g cleavage mutation), E3Δ8nt (8 bp deletion of codons 111 to 113 of exon 3), I172N, V2 81L and Q3 18X. As a result, of the 102 alleles, all but 2 of the 7 alleles were genotyped. The most common mutation was I2g with a frequency of 31% followed by I172N (23%), Q3 18X (14%), V2 81L (9%), P3 0L (3%), E3A 8nt , Of which more than two compound mutations alleles accounted for 6%. The most common mutations in patients with loss of salt were I2g (457%) and Q3 18X (26%). The most common mutations in simple type were I172N (407%) and I2g (185%). CONCLUSIONS: Of the 52 patients in this study, 73% of the alleles were mutated into the above six types of mutations. I2g and I172N were the hotspots of the mutation, and the two mutations accounted for 54%. The above results provide useful information for further genetic counseling and prenatal diagnosis services