Regulation of α7-nicotinic receptor subunit and α7-like gene expression in the prefrontal cortex of patients with bipolar disorder and schizophrenia


Albert Wong, Centre for Addiction and Mental Health, 250 College Street, Room 711, Toronto, ON, Canada M5T 1R8.


Objective:  The α7-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 α7-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 α7-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.