A Novel Variant in Dopamine Receptor Type 2 Gene is Associated with Schizophrenia.

BACKGROUND: Being the primary target of antipsychotic therapy, dopamine receptor type 2 (DRD2) remains a point of interest in schizophrenia pathology. Polymorphisms in DRD2 have been shown to alter patients' response to antipsychotics. DRD2 SNP rs6275 (C>T) have found to be associated with schizophrenia in different populations; however, data remains inconsistent. AIM OF THE STUDY: Keeping in view the genetic diversity the present study was aimed to explore association of rs6275 with schizophrenia in population from Pakistan. METHOD: Using Diagnostic and statistical Manual 5 (DSM 5) criteria, 100 schizophrenia cases and 100 controls (individuals without any psychiatric illness) were enrolled in the study. Severity of illness was determined using PANSS score. Genotyping was done via Sanger sequencing. MEGA-X was used to align the sequences, Expasy translate tool was used to translate nucleotide sequences. Difference in genotype and allele frequencies between cases and controls was determined using χ2 test. RESULT: No significant difference in genotype or allele frequencies of rs6275 (p >0.0.5) was found between cases and controls. Interestingly, a novel SNP (C>A, Pro297Thr) was spotted during electropherogram analysis at position chr11:113412805. Significant difference was found in genotype and allele frequency of this novel SNP among schizophrenia cases and controls (p = 0.003). CONCLUSION: No association of rs6275 was observed with schizophrenia in Pakistani population. However, the study found significant association of a novel missense SNP of DRD2 at chr11:113412805 (C>T) with schizophrenia in Pakistani population. A large-scale multicenter study will be required to confirm the association of this novel SNP with schizophrenia.

Synonymous polymorphism rs201256011 in dopamine receptor type 2 gene is associated with schizophrenia and PANSS score in Pakistani population: A first report.

AIM: Variations of dopamine receptor type 2 (DRD2) are among the key factors involved in the pathology of schizophrenia. Presence of certain SNPs in DRD2 gene also amend patients' response to antipsychotics. Keeping in view the genetic diversity among populations and important role of DRD2 polymorphisms in schizophrenia, we aimed to study two of its SNPs rs1801028 and rs6277 in patients with schizophrenia from Pakistan. METHODS: A total of 100 schizophrenia cases and 100 healthy controls were recruited. DNA was extracted from whole blood followed by PCR, Sanger sequencing and genotyping of two SNPs, that is, rs1801028 and rs6277. RESULTS: No association of rs1801028 and rs6277 was found with schizophrenia in Pakistani population (P > .05). Highlight of our study is the association of polymorphism rs201256011 with schizophrenia (P = .001), which is being reported for the first time. Significant association of rs201256011 was also found with Positive and Negative Syndrome Scale negative, cognitive and total score (P < .05). CONCLUSION: In conclusion, genetic variants rs1801028 and rs6277 of DRD2 are not associated with schizophrenia in Pakistani population. While, previously unreported polymorphism rs201256011 have shown significant association with schizophrenia and its severity. A large scale multicentre replication study is required to confirm the association of this SNP with schizophrenia.