a cytosolic protein that is widely expressed in tissues and contains glutamine, proline, and lysine repeats. It has no known function or homology to other proteins. The atrophin gene, at 12p13.31, encodes 1185 amino acids. The glutamine repeat (6 — 36 residues) expands to 49 — 84 residues (but the proline and lysine repeats are unchanged) in the form of spinocerebellar ataxia known as dentatorubropallidoluysian atrophy.