Two novel homozygous mutations in NPHP1 lead to late onset end-stage renal disease: A case report of an adult nephronophthisis in a Chinese intermarriage family

Abstract

Background: Nephronophthisis (NPHP) is an autosomal recessive hereditary disease with highly variable clinical characteristics for which 20 genes (NPHP1-20) have been identified. NPHP1 is the major subtype leading to pediatric end-stage renal disease (ESRD). Reports of adult NPHP1 are rare. Case presentation: Here, we report a 27-year-old male from a Chinese intermarriage family who was diagnosed as NPHP from clinical presentations and molecular genetic analysis by whole-exome sequencing. The genetic investigation revealed a novel homozygous nonsense mutation, p. E697X,37 and a novel homozygous missense mutation, p. F691 L, in the NPHP1 gene. His parents and fraternal twin harbored heterozygous mutations of the two loci and had no renal symptoms. His elder sister developed ESRD and died at 23 years of age. Conclusions: The report indicated that adult NPHP should be taken into consideration for adults with ESRD of uncertain cause. The genotype-phenotype correlation requires further investigation.