trinucleotide repeat expansion disease


trinucleotide repeat expansion disease

one of a number of diseases caused by the elongation of an array of trinucleotide repeats to two or more times the normal length in or near a gene. For example, in HUNTINGTON'S CHOREA a trinucleotide repeat expansion in the coding region of the human gene HD results in an increased tract of polyGLUTAMINE and in turn a dysfunctional gene product. Expansion in the untranslated LEADER REGION of the human gene FRMi is associated with fragile X syndrome.