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 journalArticle


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 - Jan 1 1998



  • 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
  • Psychiatry and Mental health
  • Cellular and Molecular Neuroscience

Cite this

Lindblad, K., Nylander, P. O., Zander, C., Yuan, Q. P., Stähle, L., Engström, C., Balciuniene, J., Pettersson, U., Breschel, T., Mclnnis, M., Ross, Ç. A., Adolfsson, R., & Schalling, M. (1998). Two commonly expanded CAG/CTG repeat loci: Involvement in affective disorders? Molecular psychiatry, 3(5), 405-410.