trinucleotide repeat expansion disease
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trinucleotide repeat expansion diseaseone 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.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005