Two commonly expanded CAG/CTG repeat loci: Involvement in affective disorders?

K. Lindblad, P. O. Nylander, C. Zander, Q. P. Yuan, L. Stähle, C. Engström, J. Balciuniene, U. Pettersson, T. Breschel, M. Mclnnis, Ç A. Ross, R. Adolfsson, M. Schalling

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


An association between bipolar affective disorder and CAG/CTG trinucleotide repeat expansions (TRE) has previously been detected using the repeat expansion detection (RED) method. Here we report that 89% of RED products (CAG/CTG repeats) > 120 nt (n = 202) detected in affective disorder patients as well as unaffected family members and controls correlate with expansions at two repeat loci, ERDA1 on chromosome 17q21.3 and CTG18.1 on 18q21.1. In a set of patients and controls in which we had previously found a significant difference in RED size distribution, the frequency of expansions at the CTG18.1 locus was 13% in bipolar patients (n = 60) and 5% in controls (n = 114) (P < 0.07) with a significantly different size distribution (P < 0.03). A second set of patients were ascertained from 14 affective disorder families showing anticipation. Twelve of the families had members with RED products > 120 nt. The RED product distribution was significantly different (P < 0.0007) between affected (n = 53) and unaffected (n = 123) offspring. Using PCR, a higher frequency (P < 0.04) of CTG18.1 expansions as well as a different (P < 0.02) repeat size distribution was seen between affected and unaffected offspring. In addition, a negative correlation between RED product size and the age-of-onset could be seen in affected offspring (r(s) = -0.3, P = 0.05, n = 43). This effect was due to an earlier onset in individuals with long CTG18.1 expansions. No difference in ERDA1 expansion frequency was seen either between bipolar patients (35%, n = 60) and matched controls (29%, n = 114), or between affected and unaffected offspring in the families. We conclude that expanded alleles at the CTG18.1 locus confers an odds ratio of 2.6-2.8 and may thus act as a vulnerability factor for affective disorder, while the ERDA1 locus seems unrelated to disease.

Original languageEnglish (US)
Pages (from-to)405-410
Number of pages6
JournalMolecular psychiatry
Issue number5
StatePublished - 1998
Externally publishedYes


  • Anticipation
  • Bipolar affective disorder
  • CTG18.1
  • Depression
  • ERDA1
  • Repeat expansion detection
  • SEF2-1B
  • Trinucleotide repeat expansion
  • Unipolar affective disorder

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience
  • Psychiatry and Mental health


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