Senior-Loken syndrome (SLS) is a rare genetic disorder that affects the kidneys and eyes. The main symptoms of SLS include nephronophthisis, a progressive deterioration of the kidneys, and retinal dystrophy, a loss of vision. SLS usually becomes apparent during the first year of life.
SLS is likely caused by several different types of mutations in several genes. The genes involved are NPHP1, NPHP3, NPHP4, and NPHP5, also known as IQCB1. There is limited information indicating the possibility of several types of SLS. One source suggests that SLS1 is associated with mutations in the nephronophthisis-1 gene (NPHP1), SLS3 with mutations in the NPHP3 gene, SLS4 with mutations in the NPHP4 gene, and SLS5 with mutations in the NPHP5 gene, also known as IQCB1.
The type of mutation determines the disease. The NPHP1 gene provides instructions for making the nephrocystin protein, whose function is currently unknown. This gene is defective in other disorders as well, including nephronophthisis and Joubert syndrome. The NPHP3 gene provides instructions for making a protein that interacts with the nephrocystin protein. The NPHP4 gene provides instructions for making the nephrocystin-4 protein, whose function is also currently unknown. The NPHP5 gene provides instructions for making the nephrocystin-5 protein.
SLS is inherited, or passed down from parents to children, as an autosomal recessive trait. This means that two copies of the defective gene must be inherited, one from each parent, for the disease to appear.
SLS is extremely rare, with about 150 cases reported in the scientific literature. The exact prevalence of this condition is not known. The disorder affects males and females in equal numbers.
There is no cure for SLS. Treatment aims to relieve symptoms and to prevent or manage complications. Medications, dialysis, or kidney transplantation may become necessary depending on the severity of the disease.
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types of the disease
There is limited information indicating the possibility of several types of Senior-Loken syndrome (SLS). One source suggests that SLS1 is associated with a mutation in the nephronophthisis-1 gene (NPHP1), SLS3 with a mutation in the NPHP3 gene, SLS4 with a mutation in the NPHP4 gene, and SLS5 with a mutation in the NPHP5 (IQCB1) gene. If different forms of the disease do exist, they appear to all have similar symptoms and differ only in the gene that is affected.