Arches. Photo by Daniel Chia
HOPES: Huntington's Outreach Project for Education, at Stanford
Nov
14
2010

contraction

A mutation in which the child has fewer copies of a certain codon in a gene than either of the parents. In Huntington’s disease, a contraction occurs when the child has fewer copies of the CAG codon in the Huntington gene than either of the parents. Contractions are the opposite of expansions.