Abstract
BackgroundAlterations in the dopamine transmission and receptor density are hypothesized in the pathophysiology of schizophrenia but ethnic disparities are reported to exist in disease association and therapeutic response to psychotropic medication. Antipsychotics have higher binding affinity to D2 subtype of dopamine receptor. DRD2 Cys311, TaqIB1 and TaqIA1 variants are considered to have either reduced affinity for dopamine and hypo-dopaminergic activity.MethodsWe examined the role of Taq1B, Taq1D, S311C, H313H and Taq1A polymorphisms of DRD2 gene in schizophrenia and antipsychotic treatment response in 213 patients and 196 controls from a homogenous South Indian population. A more detailed genotype phenotype association analysis was carried out to understand the disease in terms of its socio-cultural factors.ResultsH313HTT genotype was found to be associated with schizophrenia (P = 0.004) while TaqIB1B1 genotype was significantly associated with higher psychopathology score. When treatment response was considered H313HCC, TaqIA2A2 and Taq1D1D1 had higher mean improvement scores. TaqID1D1 and H313HTT genotype were found to be significantly higher in responders than in nonresponder group. Distinct shift in the LD patterns of responder and non-responder group was observed. Certain symptoms were characteristic of our patient population. Following medication the scores and presentation of these symptoms tend to vary in the responder and non-responder groups.ConclusionBased on genotype phenotype correlations it can be suggested that certain polymorphisms can be defined for their critical functions in disease and their role in treatment response in South Indian population. The present study suggests that in addition to ethnic bias, socio-cultural factors should also be considered while evaluating genotype phenotype correlations, in association and treatment response to complex disorders like schizophrenia.
Highlights
Alterations in the dopamine transmission and receptor density are hypothesized in the pathophysiology of schizophrenia but ethnic disparities are reported to exist in disease association and therapeutic response to psychotropic medication
Alterations in the dopamine transmission and receptor density have been hypothesized in the pathophysiology of schizophrenia [4]
Several studies have shown positive association of D2 subtype of dopamine receptor (DRD2) in schizophrenia [8,9,10,11,12] this was refuted by many others [13,14,15,16]
Summary
Alterations in the dopamine transmission and receptor density are hypothesized in the pathophysiology of schizophrenia but ethnic disparities are reported to exist in disease association and therapeutic response to psychotropic medication. Several studies have shown positive association of D2 subtype of dopamine receptor (DRD2) in schizophrenia [8,9,10,11,12] this was refuted by many others [13,14,15,16]. Antipsychotics have higher binding affinity to D2 subtype of dopamine receptor (DRD2) in schizophrenic patients [17]. This binding affinity is strongly correlated with the efficacy of the drugs in controlling the positive symptoms of schizophrenia [18]. Most often the association or treatment response studies have been conducted in relation to schizophrenia and not in identifying the sociocultural factors that associate with schizophrenia in presenting various symptoms
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