Study Report

Basic Info
Reference |
Mohammadi, S., 2015 PMID: 25596490
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Citation |
Mohammadi, S., et al. (2015). "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 590: 91-95.
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Disease Type |
Bipolar Disorder |
Study Design |
case-control |
Study Type |
candidate-gene association study |
Sample Size |
152 in- and out-patients BID and 173 gender- and age-matched healthy individuals |
SNP/Region/Marker Size |
2 polymorphisms |
Predominant Ethnicity |
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Population |
Kurdish population |
Gender |
76 females and 76 males for cases, 85 females and 88 males for controls |
Age Group |
adults
:
mean age of 35.5 (sd=12.3) years for cases, mean age of 33.7 (sd=11.04) years for controls
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Detail Info
Sample Diagnosis |
DSMIV-TR |
Sample Status |
Patients who met the criteria for schizoaffective or schizophrenia or mental retardation and patients with medical condition were excluded from the study. Seven patients with psychotic symptoms more than 2 weeks in the absence of a major mood episode (suspicious to schizoaffective disorder), 2 patients with comorbid mental retardation and 2 patients with medical condition (hepatitis and chronic obstructive pulmonary disorder) were excluded from the study. A positive family history of major mood disorder (at least one first-degree relative suffering from BID, bipolar II disorder or major depressive disorder) existed in 36 patients (24%). Nineteen patients (12.5%) were substance (opiate) dependent. Patients had been treated with lithium, carbamazepin, and valproic acid. A review of medical records and a semi structured interview was used to find the presence of suicide attempt in patients. |
Technique |
genotyping using PCR |
Statistical Method |
The allelic frequencies were calculated by the chromosome counting method. The degrees of significance of differences in genotype and allele frequencies of 5-HTTLPR and 5-HT2C between patients and controls were calculated using 2 test. Odds ratios (OR) were calculated as estimates of relative risk for the disease and 95% confidence intervals (CI) were obtained by SPSS logistic regression. Two-tailed Student’s t-test and ANOVA analysis were also used to compare quantitative data. The categorical variables among groups were compared using 2 test. Statistical significance was assumed at the p < 0.05 level. The Statistical Package for the Social Sciences (SPSS) logistic regression version 16.0 was used for the statistical analysis. |
Result Summary |
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. |

Other variants reported by this study for BD (count: 2)
Variant Name |
Related Gene |
Type |
Allele Change |
Risk Allele |
Statistical Values |
Author Comments |
Result Category |
5HTTLPR |
SLC6A4 |
microsatellite |
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genotypic P-value=0.037, X2=6.62 in co-dominant model, genotypic P-value=0.98, X2=0 in dominant model, genotypic P-value=0.017, X2=5.65, OR (95%CI, p)=1.79 (1.1-2.88, p=0.018) in recessive model; allelic P-value=0.11, X2=2.5
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In recessive model (SS vs. LL + LS) the frequency of SS geno......
In recessive model (SS vs. LL + LS) the frequency of SS genotype was significantly higher in patients (39.5%) than that in controls (26.8%, p = 0.017) that was associated with 1.79-fold increased risk of BID. Also, the presence of S allele increased the risk of adult-onset BID by 1.76-fold.
More...
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Positive
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5-HT2C Cys/Ser |
HTR2C |
point mutation |
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genotypic P-value=0.98, X2=0.025, genotypic P-value=0.83, X2=0.36 in females; allelic P-value=0.95, X2=0.004, allelic P-value=0.78, X2=0.073 in females, allelic P-value=0.85, X2=0.05 in males
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The frequency of 5-HT2C Ser allele in patients and controls ......
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%).
More...
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Negative
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Genes reported by this study for BD (count: 2)
Gene |
Statistical Values/Author Comments |
Result Category |
SLC6A4 |
Our findings demonstrate 5-HTTLPR polymorphism might be a risk factor for BID and adult-onset BID in......
Our findings demonstrate 5-HTTLPR polymorphism might be a risk factor for BID and adult-onset BID in Kurds population.
More...
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Positive
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HTR2C |
We found the lack of an association between 5-HT2C Cys/Ser variants and the risk of BID.
We found the lack of an association between 5-HT2C Cys/Ser variants and the risk of BID.
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Negative
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