Association of single-nucleotide polymorphism of cholecystokinin receptor A gene with schizophrenia in an Eastern Indian population.

Context: Cholecystokinin A receptor (CCK-AR) gene polymorphism is being increasingly reported in schizophrenia. It varies among different population groups but is associated with several complications of schizophrenia.

Aims: The present study was undertaken to assess whether the CCK-AR polymorphism is stabilized and is more consistently associated with schizophrenia in an Eastern Indian sub-population.

Settings And Design: It was carried out as a cross-sectional, observational, hospital-based study on 95 schizophrenia patients and 138 control subjects selected by the method of convenience.

Materials And Methods: Single-nucleotide polymorphisms located in the regulatory region of the CCK-AR gene were assessed by restriction fragment length polymorphism (RFLP) in the polymerase chain reaction (PCR) amplified product of CCK-AR gene in study subjects. RFLP was done by the digestion of the PCR product by the restriction enzyme Pst-1 followed by gel electrophoresis.

Statistical Analysis: Assessment of the stability of C/T polymorphism in the study population was done by applying Hardy-Weinberg equilibrium rule. The significance of difference in the allelic distribution between case and controls was analyzed by Chi-square (χ(2)) test and odds ratio (OR) analysis.

Result: CCK-R polymorphism was in Hardy-Weinberg equilibrium in both groups. Distribution of the C allele of this gene was significantly higher in schizophrenia patients (χ(2) = 4.35, OR = 1.51; confidence interval at 95% =1.04-2.20).

Conclusion: C/T polymorphism of the CCK-R gene is a stable polymorphism in our study population. Moreover, the C allele is significantly more abundant in schizophrenia patients imparting them a greater risk of development of complications like auditory hallucination.