Senior-Loken syndrome

Senior-Loken syndrome (SLS), also known as renal-retinal dystrophy or nephronophthisis with retinal dystrophy, is a rare autosomal recessive disorder classified among the ciliopathies — diseases caused by dysfunction of primary cilia. It is characterized by the combination of nephronophthisis (a progressive tubulointerstitial kidney disease) and retinal dystrophy (typically Leber congenital amaurosis or retinitis pigmentosa). The condition primarily affects two organ systems: the kidneys and the eyes. Nephronophthisis leads to progressive kidney damage with symptoms including excessive thirst (polydipsia), excessive urination (polyuria), and impaired urine-concentrating ability, ultimately progressing to end-stage renal disease (ESRD), often by adolescence or early adulthood. The retinal dystrophy causes progressive vision loss, which may present in infancy or early childhood with nystagmus, photophobia, and severely reduced visual acuity. In some cases, blindness may precede the onset of noticeable kidney symptoms. Senior-Loken syndrome is genetically heterogeneous, with mutations identified in several genes involved in ciliary function, including NPHP1, NPHP3, NPHP4, NPHP5 (IQCB1), NPHP6 (CEP290), and others. Diagnosis is based on clinical findings, imaging of the kidneys (which may show small kidneys with corticomedullary cysts), ophthalmologic examination including electroretinography, and genetic testing. There is currently no cure or disease-specific therapy for Senior-Loken syndrome. Treatment is supportive and includes management of chronic kidney disease, renal replacement therapy (dialysis or kidney transplantation) when ESRD develops, and ophthalmologic interventions to optimize remaining vision. Genetic counseling is recommended for affected families.

Common questions about Senior-Loken syndrome