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

expanded polyglutamine chain

occurs when a normal protein that has a certain number of glutamines in a chain is mutated, so that the number of glutamines in the chain increases, it is an expanded chain. For example in Huntington’s Disease, a normal polyglutamine chain in the huntingtin protein would have from 10 to 35 glutamines, but an expanded polyglutamine chain would have more than 40 glutamines in a row.