Serotonin transporter gene polymorphism and its association with bipolar disorder across different ethnic groups in Malaysia

• Published in: Comprehensive psychiatry 2014, Vol.55 (S1), p.S76-S81
• Main Authors: Mohamed Saini, Suriati, Nik Jaafar, Nik Ruzyanei, Sidi, Hatta, Midin, Marhani, Mohd Radzi, Azizah, Abdul Rahman, Abdul Hamid
• Format: Article
• Language: English
• Subjects: Adult; Bipolar disorder; Bipolar Disorder - ethnology; Bipolar Disorder - genetics; Confidence intervals; Deoxyribonucleic acid; DNA; Emotional disorders; Ethnic Groups - ethnology; Ethnic Groups - genetics; Family medical history; Female; Gene Frequency - genetics; Genes; Genetic Variation; Genotype; Genotype & phenotype; Humans; Illnesses; Malaysia - ethnology; Male; Middle Aged; Polymorphism, Genetic - genetics; Psychiatry; Serotonin; Twins
• ISSN: 0010-440X; 1532-8384
• DOI: 10.1016/j.comppsych.2012.12.005

Abstract Objectives The risk variants have been shown to vary substantially across populations and a genetic study in a heterogeneous population might shed a new light in the disease mechanism. This preliminary study aims to determine the frequency of the serotonin transporter gene polymorphism (5-HTTLPR) in the three main ethnic groups in Malaysia and its association with bipolar disorder. Methods This is a candidate gene association study of randomly selected forty five unrelated bipolar disorder probands and sixty six controls. Diagnosis was evaluated using the Mini International Neuropsychiatric Interview (M.I.N.I). The control group consisted of healthy volunteers without personal psychiatric history and family history of mood disorder. Patients' whole blood was collected for genotyping. Results This study revealed that the frequency of the short variant of 5-HTTLPR in healthy control group was highest in Indians (42.9%) followed by Malays (23.5%) and was absent in Chinese. The association between the homozygous ss genotype of the 5-HTTLPR polymorphism with bipolar disorder was not found in the pooled subjects (χ2 = 1.52, d.f. = 1, p = 0.218, OR = 4.67, 95% C.I. = 0.69–7.58) and after stratification into Malays (p = 0.315, OR = 2.03, 95% CI = 0.50–8.17), Indians (p = 0.310; OR = 0.44, 95% CI = 0.21–0.92) and Chinese. Conclusion The differences in the frequency of the short allele of 5-HTTLPR across the three main ethnic groups in Malaysia were noteworthy. The present study showed no significant association between the homozygous short variant of the 5-HTTLPR and bipolar disorder in the pooled subject and after stratification into the three main ethnic groups in Malaysia.