Tri-nucleotide expansions in human neuro-muscular disease
Trinucleotide repeat diseases were unsuspected prior to
investigation of Huntington Disease. They are now known to
be quite common: CAG expansions are implicated in a
number of neuro-muscular conditions, where the consequent poly-Glu
repeat within the translated product produces plaques
that interfere with normal function. Expression of the
modified protein therefore 'dominates' the standard
product: the allele behaves as a dominant.
Figure © 2012 TA Brown, Introduction
to Genetics (1st ed.); additional
text © 2014 by Steven M. Carr