MYO1A

The MYO1A gene provides instructions for making a protein called myosin IA, 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 IA is made in intestinal epithelial cells, which are cells that line the walls of the intestine. These cells have fingerlike projections called microvilli that absorb nutrients from food as it passes through the intestine. Based on their appearance, groups of these microvilli are known collectively as the brush border. Microvilli contain bundles of actin filaments that provide structural support and are used for internal transport. Although the precise function of the myosin IA protein is unknown, it is active in the brush border and is probably involved in transporting nutrients from food.

Myosin IA is also present in the inner ear and appears to be involved in normal hearing. Researchers have not determined the protein's role in the inner ear.

nonsyndromic deafness - associated with the MYO1A gene

At least eight mutations in the MYO1A 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 DFNA48. Most of these genetic changes alter single protein building blocks (amino acids) in the myosin IA protein. In one case, a mutation adds an extra amino acid to the protein. These mutations probably alter the structure of myosin IA or cause an abnormally small, nonfunctional version of the protein to be made. Researchers have not determined how mutations in the MYO1A gene could result in hearing loss, and it remains unclear whether MYO1A mutations impair hearing.