Analysis of clinical phenotype and genotype of LAMB2 mutation / 中华肾脏病杂志

ABSTRACT

Objective:To report two cases of steroid-resistant nephrotic syndrome (SRNS) caused by LAMB2 gene mutation, and summarize the characteristics of genotype, clinical and pathological phenotypes of children with LAMB2 gene mutation. Methods:Two cases with SRNS caused by LAMB2 gene mutation were from Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology in December 2013 and September 2019. The demographic, family history and clinical data of two cases were collected, and the peripheral blood genomic DNA was captured and sequenced by whole exome sequencing. PubMed, Medline, CNKI and Wanfang databases were searched to summarize the clinicopathological phenotypes and genotypes of patients with LAMB2 mutation. Results:Among the two cases with SRNS caused by LAMB2 gene mutation, the clinical phenotypes were all manifested as nephrotic level of proteinuria and hypoalbuminemia, and there was no extrarenal clinical manifestation. One case presented with basement membrane delamination and the other with focal segmental glomerulosclerosis (FSGS). LAMB2 mutations of two cases were Exon32 c.5390G>T(p.Cys1797Phe), Exon19 c.2557C>T(p.Arg853*) and Exon27 c.4370G>A(p.R1457Q), Exon23 c.3325G>A(p.E1109K), respectively. In literature retrieval, there were 37 cases with LAMB2 gene mutation, including 24 cases with renal biopsy data, 13 cases of focal segmental glomerulosclerosis (FSGS), 4 cases of minimal change disease, one case of diffuse mesangial sclerosis, one case of IgM nephropathy, two cases of thin basement membrane nephropathy, and three cases of mesangial hyperplasia. Among them, eight cases had basement membrane delamination tear. Among the 37 cases, 11 cases were homozygous, 22 cases were complex heterozygosity, and 4 cases were heterozygous mutation. Conclusions:LAMB2 mutation may cause delamination tear of glomerular basement membrane. The clinical phenotype is congenital nephrotic syndrome or SRNS. The literature review shows the extrarenal manifestations caused by LAMB2 mutation are mostly various ocular abnormalities, as well as respiratory, digestive and nervous system abnormalities, and the time of progression to end-stage renal disease is also different.