CALCYON gene variation, schizophrenia, and cocaine dependence

Calcyon is a brain-specific D1 dopamine receptor-interacting protein, with a potential role in D1-mediated physiological processes, including motor control, reward mechanisms, and cognitive processes. Our objective was to investigate the relationship between polymorphism of the CALCYON gene and (1) schizophrenia and (2) cocaine dependence in African-American (AA) and European-American (EA) subjects. Two single nucleotide polymorphisms (SNPs) at the CALCYON locus were genotyped in 70 AA and 206 EA individuals with schizophrenia and 90 AA and 118 EA individuals with cocaine dependence. The control group was comprised of 46 AA and 207 EA subjects screened to exclude those with psychiatric or substance use disorders. The specific polymorphisms studied were markers +295214G/A and +297151T/G. Comparisons of allele and haplotype frequencies between cases and controls were performed with the Fisher's Exact Test. Linkage disequilibrium (LD) between these two SNPs was calculated with the 3LOCUS program. No alleles or haplotypes were found to be associated with schizophrenia or cocaine dependence either in AA or EA subjects. The markers +295214G/A and +297151T/G are in the same haplotype block in all subgroups. Allele and haplotype frequencies differed significantly between EA and AA subjects. These results suggest that these two genetic variants in the CALCYON gene do not play a major role in predisposition to either schizophrenia or cocaine dependence in AA or EA subjects. Furthermore, these findings begin to establish a haplotype map for this gene in the AA and EA populations.