The clinicogenetic features of Japanese patients with nephronophthisis

Abstract

Nephronophthisis (NPH), an inherited kidney disease with a poor prognosis, is caused by abnormality of an NPHP gene. There are three subtypes of NPH regarding the development of end-stage renal disease, and three different genes responsible for each subtype have been identified. The main pathogenesis of this disease is the dysfunction of primary cilia called ciliopathy. NPHP1 to NPHP13 have been identified as the genes responsible for various types of NPH. NPHP1 and NPHP4 are the main genes responsible for NPH, but this disorder may occur with no abnormality in these genes; other, presently undetermined genes may be involved. The characteristics of Japanese NPH patients are as follows; (1) difficulty of detection by urine mas screening system, (2) high incidence of hypotonic urine (>1.010) and/or low-molecular weight proteinuria, (3) sometimes association with extrarenal findings such as retinitis pigmentosa, (4) NPHP1 abnormality most often by large deletion.