Novel mutation in the nephrin gene of a Japanese patient with congenital nephrotic syndrome of the Finnish type

Background. Congenital nephrotic syndrome (CNS) of the Finnish type is a rare autosomal-recessive disorder. Kestila et al reported that a positionally cloned gene for a novel glomerular protein nephrin is mutated in CNS. Most Finnish patients have one of two mutations. In this study, we described a Japanese CNS family associated with a novel missense point mutation in the nephrin gene. Methods. Reverse transcription-polymerase chain reaction, polymerase chain reaction, and sequence analysis were used. Results. The patient had the three missense mutations homozygously. One mutation was already reported as sequence variant. The two other novel mutations were the GAG to AAG transition, leading to a Glu(447)Lys and the GAC to GTC transition, predicting an Asp(819)Val substitution in the nephrin protein. Conclusion. Our findings indicate that an abnormality of nephrin may cause CNS of the Finnish type in Japanese subjects.