A number of inherited disorders, most of which are neurodegenerative in nature, are caused by expansion of CAG repeats within the coding region of the causative gene, resulting in an expanded run of glutamine (Q) residues in the encoded protein. This report includes general information about this class of diseases. See the "Related diseases" section below for links to reports for specific diseases and for the "polyQ-only" model systems developed in Drosophila (FBhh0000001). Runs of short nucleotide repeats may also result in pathologies effected via the transcript(s) of a gene, rather than the protein products. Work in Drosophila addressing this phenomenon is described in a separate disease report; see RNA-repeat diseases (FBhh0000059).
[updated Mar. 2016 by FlyBase; FBrf0222196]