蛋白尿综合征一家系致病基因研究

Mutation analysis of genes in a family with proteinuria syndrome

目的 分析1个以蛋白尿为主，伴镜下血尿家系的临床特征，并对可能的致病基因进行筛查。方法 调查1个以蛋白尿为主，伴镜下血尿的汉族家系，收集临床资料，绘制家系图谱，并对家系中所有成员进行尿液筛查，并留取其外周血，对尿液筛查异常的一对同胞及其父母进行NPHS1和NPHS2基因所有外显子、WT1基因外显子8和9，以及外显子和内含子交界区直接测序。结果 该家系共有3代，17名成员。同一代中发病的有2例，男、女各1例，平均发病年龄1.3岁。临床资料分析显示，该家系临床特点符合常染色体隐性遗传。先证者表现初发型激素耐药肾病综合征，肾脏病理光镜下表现局灶增生性肾小球肾炎，免疫荧光 IgA、IgM、C1q和C3均阴性，Ⅳ型胶原蛋白α1、α3和α5链均阳性，电镜下基底膜正常，足突融合。2例患儿在 NPHS2基因外显子3和4上均存在杂合p.R138Q（c.413G 〉A）和 p.L156FfX11（c.467-468insT），其中 p.R138Q 错义突变来自母亲，p.L156FfX11为移码突变来自父亲，2个突变均为报道的致病性突变，前者为NPHS2基因最常见的突变，后者仅在我国人群中报道。结论 p.L156FfX11突变可能是我国肾病综合征儿童的一个特异性突变。NPHS2基因突变不仅可引起蛋白尿，也可伴镜下血尿。NPHS2基因突变引起的肾脏病理不仅可表现为局灶节段性肾小球硬化，还可以为局灶增生性肾小球肾炎，肾脏病理改变可能仅是疾病病程的反映。

Objective To investigate the clinic features of a family present with proteinuria and microscopic hematuria, and screen 3 commonly pathogenic genes of hereditary proteinuria syndrome. Methods Clinical data of a family present with proteinuria and microscopic hematuria were collected and analyzed. Pedigree of the family was drawn. Urine screening was-conducted to all members of the family. Peripheral blood was taken from all members of the family. Direct sequencing of all exons of NPHS1 and NPHS2 gene and exon 8,9 of WT1 gene was performed on 2 patients and their parents. Results The family had 3 generations, 17 members. There were 2 sibling patients in the family. One was a female,the other was male. The average age onset was 1.3 years. Analysis of clinical data revealed the family genetic features was consistent with the autosomal recessive inheritance. The proband presented with initial steroid -resistant nephrotic syndrome. His renal pathological changes under light microscope showed focal proliferative glomerulonephritis. Under immunofluorescence microscope IgA, IgM, C1q and C3 were all negative, but type 1V collagen α1,α3 and α5 chains were positive. The basement membrane was normal,and foot process fusion was found under the electron microscope. Two patients both had heterozygous p. R138Q（ c. 413G 〉 A） and p. L156FfX11 （c. 467 - 468insT） in the NPHS2 gene exon 3 and 4. Analysis mutation of NPHS2 gene in the family revealed that p. R138Q missense mutation and p. L156FfX11 frameshift mutation were from their parents, respectively. Two mutations had been reported before,which were disease - causing mutation. The former was the most common mutation of NPHS2 gene in European population,but the latter only had been reported in the Chinese population. Conclusions The p. L156FfX11 mutation may be a specific mutation in Chinese children with nephrotic syndrome. Mutations of NPHS2 gene can not only cause proteinuria,but also be associated with microscopic hematuria. Renal pathological changes caused by NPHS2 gene mutation could not only become focal segmental glomerulosclerosis, but also be focal proliferative glomerulonephritis. Renal pathological changes may simply reflect the course of the disease.