Retinitis pigmentosa and renal failure in a patient with mutations in INVS

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.