中国南方汉族人家族性激素耐药型肾病综合征家系NPHS2基因突变

Mutations in NPHS2 in familial steroid-resistant nephrotic syndrome in Southern Chinese Han ethnic group

目的分析中国南方汉族人家族性激素耐药型肾病综合征（SRNS）家系NPHS2基因突变及其特点。方法研究对象为A、B、C3个南方汉族人SRNS家系先证者及其姐和父母，50例尿检正常的南方汉族成年人作为对照人群。取所有研究对象外周静脉血3ml，提取基因组DNA，PCR扩增NPHS2全部8个外显子及其周围的部分内含子和启动子全长序列，对PCR产物直接进行DNA序列测定。结果对3个南方汉族人SRNS家系先证者NPHS2全部8个外显子及其周围的部分内含子进行突变分析，未发现NPHS2突变，仅在外显子8上检测到1个NPHS2基因多态性（954T〉C）。在3个家系的先证者及其姐和父母的NPHS2启动子上检测到6个变异：-1715A〉G、-1709G〉A、-1000A〉T、-670C〉T、-116C〉T和-51G〉T。其中5个变异（-1709G〉A、-1000A〉T、-670C〉T、-116C〉T和-51G〉T）在100条正常染色体中也有检出，它们在SRNS患者中的等位基因频率分别与在对照人群中的等位基因频率比较差异均无统计学意义（P〉0．05）；另1个变异（-1715A〉G）在家系C的先证者及其母亲（尿检正常）中检出，为杂合变异，而在100条正常染色体中未发现。-1000A〉T为新发现的NPHS2基因多态性，-1715A〉G为新发现的NPHS2变异。结论NPHS2基因突变不是本研究3个南方汉族人家族性SRNS家系的主要致病原因。

Objective Mutations in NPHS2 mapped to 1q25-q31 and encoding podocin, which is exclusively expressed in glomerular podocytes, are responsible for autosomal recessive familial steroid- resistant nephrotic syndrome （SRNS） with minor glomerular abnormalities or focal segmental glomerulosclerosis. Different groups from European and North American countries have screened NPHS2 mutations in familial SRNS with recessive inheritance, documenting a mutation detection rate of 45%-55% in families. This study aimed to examine mutations in the NPHS2 gene in Southern Chinese Han ethnic group patients with familial SRNS. Methods Genomic DNA from 3 probands from Southern Chinese Han families with autosomal recessive SRNS, and their siblings and parents was isolated and analyzed for all eight exons, exon-intron boundaries and promoter of NPHS2 using the pelymerase chain reaction and direct sequencing. Results No mutation of NPHS2 in all eight exons and exon-intron boundaries was identified in the 3 probands. However, a polymorphism of 954T 〉 C in exon 8 was detected in all the 3 probands and some controls, and 5 variants of NPHS2 promoter, - 1709G 〉 A, - 1000A 〉 T, - 670C 〉 T, - 116C 〉 T and -51G 〉 T, were identified in some patients and controls, indicating that these variants are polymorphisms. One heterozygous variant of NPHS2 promoter, - 1715A 〉 G, was also identified in one proband and her mother whose urinalyses were normal, whereas it was not found in any of the 50 controls. There was no significant difference in the allelic frequencies of - 1709G 〉 A, - 1000A 〉 T, - 670C 〉 T, - 116C 〉 T and -51G 〉 T polymorphisms between the patients and controls. Conclusion NPHS2 mutations are not a major cause of familial steroid-resistant nephrofic syndrome in Southern Chinese Han ethnic group included in the study.