CLRN1

The CLRN1 gene provides information for making a protein called clarin 1. This protein is probably involved in normal vision and hearing. Clarin 1 has been found in several tissues in the body, including hair cells, which are sensory cells in the inner ear that help transmit sound and motion signals to the brain. This protein is also active in the light-sensing tissue that lines the back of the eye (the retina). Although the function of clarin 1 has not been determined, studies suggest that it plays role in nerve cell communication in the inner ear and retina. Clarin 1 may be important for the function of synapses, which are junctions between nerve cells where cell-to-cell communication occurs.

Usher syndrome - caused by mutations in the CLRN1 gene

At least 10 mutations in the CLRN1 gene have been identified in people with Usher syndrome. Several of these mutations change single protein building blocks (amino acids) in the clarin 1 protein. In some cases, these mutations lead to the production of an abnormally short version of the protein or prevent the cell from making any functional clarin 1. Other mutations insert or delete small amounts of DNA in the CLRN1 gene, which probably impairs the normal function of clarin 1. Researchers have not determined how a missing or altered clarin 1 protein leads to the signs and symptoms of Usher syndrome.

Two particular CLRN1 mutations have been identified in families of Finnish ancestry. One mutation, sometimes called Finn(major) and written as Tyr176Ter, leads to the production of an abnormally short, nonfunctional version of clarin 1. The other mutation, Met120Lys, also known as Finn(minor), substitutes the amino acid lysine for the amino acid methionine at protein position 120. This mutation may disrupt the protein's normal function.