Evidence that brain MAO A activity does not correspond to MAO A genotype in healthy male subjects

Background: A functional polymorphism in the promoter region of the monoamine oxidase A (MAO A) gene has two common alleles that are referred to as the high and low MAO A genotypes. We report the first in vivo human study to determine whether there is an association between MAO A genotype and brain MAO A activity in healthy male subjects. Methods: Brain MAO A activity was measured with positron emission tomography and [C-11]clorgyline in 38 healthy adult male nonsmokers genotyped for MAO A polymorphism. Results: There was no significant difference in brain MAO A activity between the high (n = 26) and low (n = 12) MAO A genotypes. Conclusions: The lack of an association between the high and low MAO A genotype and brain MAO A activity suggests that this polymorphism by itself does not contribute to differences in brain MAO A activity in healthy adult male subjects.