The [[human genome]] contains two atrophin genes; DRPLA has been correlated to the expansion of the polyglutamine region of the [[ATN1|atrophin-1]] gene on chromosome 12p13.3
Atrophin-1 (ATN1) encodes a hydrophilic 1184 amino acid protein with several repetitive motifs including a serine-rich region, a variable length polyglutamine tract, a polyproline tract, and a region of alternating acidic and basic residues.