Melatonin Receptor Gene Polymorphism in Bipolar-I Disorder

In patients with Bipolar-I Disorder (BD-I), circadian rhythm and sleep disorders are frequently observed. Melatonin is a main regulatory hormone for the circadian rhythm. Certain studies have shown the relationship of melatonin receptor gene polymorphism with psychiatric diseases. In this study, it was aimed to investigate the relationship between BD-I and -184T>C (rs2119882) polymorphism in melatonin receptor 1A (MTNR1A) gene and -1193C>T (rs4753426) polymorphism in melatonin receptor 1B (MTNR1B) gene.

The study included 108 patients diagnosed with BD-I and 95 healthy people as the control group. Real-time PCR (RT-PCR) method was used to evaluate the polymorphism of MTNR1A gene-184T>C. Genotyping of MTNR1B gene-1193C>T polymorphism was done by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

In terms of MTNR1B gene-1193C>T polymorphism, homozygous CC genotype was found to be increased in BD-I patient group compared to the control group (p <0.05). Similarly, a statistically significant difference was found between the patients and the control group in terms of allele frequencies too (p <0.05). However, no relation between BD-I and MTNR1A gene-184T>C polymorphism was found (p >0.05).

The results of the study revealed that MTNR1B gene-1193C>T polymorphism may play a role in BD-I genetic etiology and may be among the causes of sleep disorder and circadian rhythm disorder seen in these patients.