中国人家族性早发2型糖尿病／MODY家系HNF-1alpha基因缺陷的分子筛查

Molecular Scanning on Hepatocyte Nuclear Factor-1 Alpha（ HNF-1 alpha） Gene in Chinese Familial Early-onset Type 2 Diabetes Mellitus/MODY Pedigrees

目的通过对疑为MODY的中国人家族性早发2型糖尿病患者HNF-1alpha基因分子筛查，探求该基因的分子缺陷是否为中国人家族性早发2型糖尿病／MODY家系的主要致病基因；同时期望能寻找到HNF-1alpha致病基因新的突变位点。方法对7个疑为MODY的中国人早发2型糖尿病家系先证者进行HNF-1alpha全基因外显子的突变筛查——DNA直接测序以明确具体的核酸突变及其编码的氨基酸突变。对测序明确的突变类型用DHPLC方法筛查出标准突变峰型，并用同样的条件对家系中其他成员进行HNF-1alpha相关位点基因扫描。结果在7个家系先证者中分别发现HNF-1alpha基因编码区的Leu17Leu同义变异，I27L错义变异，E105V、E73K和G184W错义变异，Leu459Leu同义变异，Gln486Gln同义变异，S487N和S574G错义变异。家族性早发2型糖尿病人群127L各等位基因频率分别为A0．70，C0．30，其中4例127L位点的CC基因型纯合变异均为2型糖尿病患者，但家系内不同基因型频率关联分析无统计学意义（0．25〈P〈0．50）。结论尽管I27L变异在各家系中无典型共分离现象，但在两个家系中发现的4例该位点CC基因型纯合变异均为2型糖尿病患者，因此推测HNF-1alpha基因I27L位点的CC基因型可能参与了2型糖尿病的致病过程。需要对在先证者中发现的E73K、E105G、G184W拟为突变的位点进行家系内其他成员的分子缺陷筛查，以期望证实为新致病位点。

Objective To explore whether HNF-1alpha gene mutations are the main genetic disorders which could cause the diseases in Chinese familial early-onset type 2 diabetes mellitus/MODY pedigrees. Methods Direct sequencing of all the exons of HNF-1 alpha gene was given to 7 probands of Chinese early-onset type 2 diabetes pedigrees who were suspected to be MODY. Denaturing high-performance liquid chromatograph （DHPLC） was used to filtrate the standard pictures for the mutations known after HNF-1 alpha gene sequencing. Using the same conditions of DHPLC to scan the same mutation in the rest members of the 7 pedigrees. Results We found Leul7Leu, Leu459Leu and Gln486Gln with same sense mutations and I27L, E105G, E73K, G184W, S487N and S574G with mistake sense mutations in 7 probands. The I27L polymorphism allelic frequency in Chinese familial early-onset type 2 diabetes mellitus were A 0.70, C 0.30 respectively, and all of four CC genotype subjects were diabetes mellitus in 2 pedigrees, but the genotype frequency association analysis in all members of pedigrees had no difference between each other （0.25 〈 P 〈 0.50）. Conclusion Although HNF-1 alpha gene I27L polymorphism was not definitely co-segregated with all the Chinese early-onset type 2 diabetes mellitus pedigrees＇ members, but all of four CC genotype family members were diabetes mellitus. Thus, we concluded that the CC genotype of HNF-1 alpha gene I27L polymorphism might play an important role in causing the type 2 diabetes mellitus. We still need to do further research on HNF-1 alpha gene E73K, E 105G and GI84W mutations in order to make sure whether they are new disease-associated gene mutations.