Background: Nephronophthisis (NPHP) is an autosomal recessive disease, which is the most common genetic cause of end-stage renal disease in the first three decades of life. The disease is caused by mutations in the NPHP 1-5 genes, and is referred to as NPHP types 1-5, respectively. The association of NPHP and retinitis pigmentosa (RP) is known as Senior-Loken syndrome (SLS). The RP is associated with 10% of cases of NPHP types 1, 3 and 4, and all cases of NPHP type 5, but never in NPHP type 2, the infantile form of NPHP. The NPHP type 2 is distinguished from other types of NPHP by its early age of onset and by cystic enlargement of the kidneys.
Methods: Mutational analysis of all five NPHP genes was performed by exon sequencing in a child with infantile NPHP and RP from a consanguineous kindred.
Results: A homozygous mutation was identified in exon 13 of inversin (INVS) (C2719T, R907X) in this child.
Conclusions: This is the first report of the presence of RP in a patient with NPHP type 2 and INVS mutations. This report now extends the association of RP with NPHP to NPHP type 2.