trinucleotide repeat expansion(redirected from Trinucleotide repeat disorders)
Also found in: Medical, Wikipedia.
trinucleotide repeat expansion[‚trī¦nü·klē·ə‚tīd ri′pēt ik‚span·shən]
An increase in the number of copies of a trinucleotide that is normally already present in multiple adjacent copies. For example, the X-linked mental retardation 1 (XLMRI) locus in humans usually contains 6-50 tandem repeats of CCG, but this is expanded to 200-2000 copies in the fragile-X syndrome.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.