NPHS1 gene mutation in Japanese patients with congenital nephrotic syndrome

Background and Methods. The NPHS1 gene was analysed in different five Japanese patients with congenital nephrotic syndrome (CNS) from the patients in a previous report (Sako M, Nakanishi K, Obana M et al. Analysis of NPHS1, NPHS2, ACTN4, and WT1 in Japanese patients with congenital nephrotic syndrome. Kidney Int 2005; 67: 1248-1255) that suggested that the mutation of NPHS1 was not a major cause of CNS in Japanese patients. Genomic DNA was extracted from leukocytes, and all exons and exon-intron boundaries were analysed for NPHS1 using polymerase chain reaction and direct sequencing. Results and Conclusions. Compound heterozygous mutations of NPHS1 were found in four patients and homozygous mutations in one patient. Interestingly, three patients out of five had the same mutation in NPHS1: nt2515(delC). Parents who had this mutation heterozygously were from neighbouring prefectures. Two among five patients in this research and one in the previous report (Kidney Int 2005; 67: 1248-1255) had the same mutation: 736G > T in exon 7. All mutations including these two mutations except for one have never been reported outside of Japan yet.