This tract has never been found in patients, and might be more similar to that usually found in the huntingtin mutant protein associated with juvenile forms of Huntington disease, which are clinically distinct (and possibly have a different molecular basis of toxicity) from the forms found in older patients associated with shorter, but still pathological tracts (polyQs ranging from 36 to 60) (Martindale et al., 1998). This evidence concerns the gene HTT and juvenile Huntington disease.