MYO6

The MYO6 gene provides instructions for making a protein called myosin VI, which is part of a group of proteins called unconventional myosins. These proteins, which have similar structures, each play a role in transporting molecules within cells. Myosins interact with actin, a protein that is important for cell movement and shape. Researchers believe that myosins use long filaments of actin as tracks along which to transport other molecules.

Myosin VI is produced in the inner ear as well as in many other cell types. In the inner ear, myosin VI plays a role in the development and maintenance of hairlike projections called stereocilia. Stereocilia, which are rich in actin, line the inner ear and bend in response to sound waves. This bending motion is critical for converting sound waves to nerve impulses, which is an essential process for normal hearing.

nonsyndromic deafness - caused by mutations in the MYO6 gene

At least three mutations in the MYO6 gene have been identified in people with a form of nonsyndromic deafness (hearing loss without related signs and symptoms affecting other parts of the body) called DFNB37. These mutations cause an autosomal recessive form of nonsyndromic deafness. Autosomal recessive inheritance means that two copies of the gene in each cell are altered. Some of these mutations lead to changes in single amino acids (the building blocks of proteins) in the myosin VI protein. Other mutations cause the cell to produce an abnormally short version of myosin VI. MYO6 mutations probably alter the function of myosin VI, which disrupts the structure and organization of stereocilia and leads to hearing loss.

At least one mutation in the MYO6 gene causes an autosomal dominant form of nonsyndromic hearing loss called DFNA22. Autosomal dominant inheritance means that one altered copy of the gene in each cell is sufficient to cause the condition. This mutation leads to a change in a single amino acid in a critical region of the myosin VI protein, impairing its normal function. Altering the function of myosin VI disrupts the structure and organization of stereocilia, leading to hearing loss. Additionally, there is evidence that a mutation in the MYO6 gene can cause heart problems in some affected individuals.