CTG18.1 and ERDA-1 CAG/CTG repeat size in bipolar disorder

Several groups have reported association between large CAG/CTG repeat seque nces in the genome and bipolar disorder using the Repeat Expansion Detectio n (RED) method. Unfortunately, the RED method cannot identify the specific repeat(s) responsible for these findings but it has recently been proposed that around 90% of the large CAG/CTG repeats detected by RED can be explain ed by repeat size at either CTG18.1, which maps to 18q21.1,or ERDA-1(also k nown as Dir 1), which maps to 17q21.3. These data suggest that the previous associations between bipolar disorder and large CAG/CTG repeats might be e xplained at least in part by a specific association between bipolar disorde r and either or both of these loci. However, using a case control study des ign, we find no evidence for such associations. Thus we conclude that in ou r sample, the previous RED associations are not a result of large CAG/CTG r epeats at CTG18.1 or ERDA-1. (C) 1999 Academic Press.