The serotonin transporter (5-HTTLPR) but not serotonin receptor (5-HT2C Cys23Ser) variant is associated with bipolar I disorder in Kurdish population from Western Iran

Neurosci Lett. 2015 Mar 17;590:91-5. doi: 10.1016/j.neulet.2015.01.027. Epub 2015 Jan 14.


The role of 5-HTTLPR and 5-HT2C Cys23Ser polymorphisms in the psychopathology of mood disorders and suicide behavior is controversial. The aim of present study was to investigate the association between 5-HTTLPR and 5-HT2C Cys23Ser variants and susceptibility to bipolar I disorder (BID). The 5-HT2C genotypes were studied in 152 patients with BID and 173 gender- and age-matched healthy individuals with Kurds ethnic background from Western Iran using PCR and PCR-RFLP methods. In recessive model (SS vs. LL+LS) the SS genotype was associated with 1.79-fold increased risk of BID (p=0.018). Also, the presence of S allele increased the risk of adult-onset BID by 1.76-fold (p=0.027). No association was detected between 5-HTTLPR genotypes and alleles with suicide attempt. The frequency of 5-HT2C Ser allele in patients and controls were 12.3 and 12.5%, respectively. Mutant allele of HT2C Ser had higher frequency in female (14.7%) than male (10.5%, p=0.27) patients. The frequency of HT2C Ser allele in patients with a family history of BID tended to be higher (15.7%) than those without a family history of the disease (11.8%). The frequency of HT2C Ser allele in suicide attempter women was higher (16.7%) than those without a suicide attempt (14.3%). Our findings demonstrate 5-HTTLPR polymorphism might be a risk factor for BID and adult-onset BID in Kurds population. However, we found the lack of an association between 5-HT2C Cys/Ser variants and the risk of BID.

Keywords: 5-HT2C Cys/Ser; 5-HTTLPR; Bipolar I disorder; Polymorphism; Suicide; Western Iran.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bipolar Disorder / ethnology
  • Bipolar Disorder / genetics*
  • Bipolar Disorder / psychology
  • Female
  • Genetic Association Studies
  • Genetic Predisposition to Disease
  • Humans
  • Iran
  • Male
  • Middle Aged
  • Polymorphism, Genetic
  • Receptor, Serotonin, 5-HT2C / genetics*
  • Serotonin Plasma Membrane Transport Proteins / genetics*
  • Suicide


  • Receptor, Serotonin, 5-HT2C
  • Serotonin Plasma Membrane Transport Proteins