Regulation of α 7‐nicotinic receptor subunit and α 7‐like gene expression in the prefrontal cortex of patients with bipolar disorder and schizophrenia

Objective:  The α 7‐nicotinic receptor subunit gene (CHRNA7) is located at chromosome 15q13–14, a region previously linked with schizophrenia. Genetic association and mRNA expression studies also implicate CHRNA7 in schizophrenia. The CHRNA7 gene has a partial duplication that constitutes the α 7‐like nicotinic receptor gene (CHRFAM7A). We hypothesized that major psychoses could affect the expression of both CHRNA7 and CHRFAM7A. Method:  CHRNA7 and CHRFAM7A mRNA levels were measured in postmortem prefrontal cortex (donated by the Stanley Foundation) from subjects with schizophrenia, bipolar disorder and unaffected controls ( n  = 35 each). Results:  The mRNA levels of alpha7 and α 7‐like genes have a positive correlation overall ( r  = 0.25; P  = 0.009), however, there is no significant difference in the expression of CHRNA7 among the three diagnostic groups. Conclusion:  This correlation is driven by the bipolar group ( r  = 0.43; P  = 0.009), and is absent in schizophrenia and unaffected controls, suggesting an alteration in the CHRNA7:CHRFAM7A ratio in bipolar disorder.