甘露聚糖结合凝集素基因多态性与血清蛋白表达水平的关系

The relationship between gene polymorphisms and serum protein level of mannan-binding lectin

目的了解汉族儿童甘露聚糖结合凝集素(MBL)第一外显子54密码子的基因多态性以及与血清MBL蛋白水平的关系。方法用ELISA方法检测71例儿童血清MBL水平,用聚合酶链反应-限制性内切酶片段长度多态性分析(PCR-RFLP)方法对第一外显子54密码子基因多态性进行分析,比较不同基因型的血清蛋白质表达水平,并测定部分PCR产物的核苷酸序列。结果汉族人群MBL基因第1外显子54密码子3种基因型为GGC/GGC(77.5%)、GGC/GAC(18.3%)、GAC/GAC(4.2%),等位基因GGC(0.87)出现频率较GAC(0.13)高;低MBL水平基因型为GGC/GGC(12.5%)、GGC/GAC(75.0%)、GAC/GAC(12.5%),GGC/GAC基因型及等位基因GAC(0.50)频率较正常MBL组(0.03)高(P<0.005);GGC/GGC基因型的血清MBL的水平比GGC/GAC基因型明显增高[(3.67±2.10)μg/ml,(0.10±0.05)μg/ml,P<0.001],GGC/GGC基因型汉族人群血清水平较巴布亚新几内亚人[Papua NewGuinea,(2.45±0.82)μg/ml]明显增高(P<0.001);发现MBL第一外显子15、21、58、61密码子的突变。结论第一外显子第54密码子表现不同基因多态性分布,并对应不同的血清MBL水平。主要是GGC/GAC导致低血清MBL水平,但可能存在除52、54、57密码子外的第一外显子其他部位的基因多态性导致血清MBL蛋白质表达的种族差异。

Objective To identify the relationship of gene polymorphism at code 54 of exon 1 with sennn protein level of mannose-hinding lectin（MBL）. Methods To detect the serum MBL level and observe the mutation on code 54 of exon 1 of 71 Hart people with enzyme-linked immunosdsordent assay and polymerase chain reaction（PCR）-restriction fragment length polymorphism（RFLP）, then to compare the difference among serum MBL levels caused by each genotype. Results The mutations at code 54 of exon 1 had three genotypes： GGC/GGC （77.5%）, GGC/GAC （18.3%） and GAC/GAC（4.2% ） in Han people. The probability of GGC allele（0.87） was more than allele GAC（0.13）. The polymorphisms within exon 1 of MBL were identified in low serum MBL group,GGC/GGC（12.5%）, GGC/GAC（75.0%） and GAC/GAC （12.5%）. The GGC/GAC genotype and GAC allele（0.50） had hitcher frequency of occurrence as compared with normal serum MBL group（ P 〈0.005）. difference among serum MBL levels caused by GGC/GGG, GGC/GAC, GAC/GAC was striking[（3.67±2.10） μg/ml, （0.10±0.05）μg/ml, （0.20±0.17）μg/ml, P〈0.001], and the serum MBLlevel expressed by GGC/ GGC of Han people was higher than that of Papua New Guinea population[ （2.45 ± 0.82） μg/ml, P 〈 0.001 ]. The novel mutations at codes 15, 21, 58, 61 of exon 1 have been found. Conclusion The polymorphism of genotypes（GGC/GGG, GGC/GAG, GAC/GAC） result from mutations on the code 54 which control serum MBL level, and there are possible mutations at other codes besides codes 52, 54, 57 leading to ethnic difference on MBL level low serum MBL concentration of Hart people was mostly caused by GGC/GAC.