Platelet monoamine oxidase activity is related to MAOB intron 13 genotype

Monoamine oxidase (MAO) play a critical role in the degradation of endogeno us and exogenous amines throughout the body. There are two distinct MAO iso forms, MAO-A and MAO-B, which both are encoded in genes on the X chromosome . Alterations in MAO-B activity have previously been connected with several neurological disorders. Platelet MAO (trbc-MAO) is exclusively of the B-ty pe and the catalytic activity of this enzyme is under strong, yet unknown, genetic control. Specific trbc-MAO activity has been reported to be increas ed in certain neurodegenerative diseases and to correlate with personality traits such as sensation seeking and impulsiveness. In the present study, w e investigated if trbc-MAO activity is associated with genotype at a variab le region (A/G dimorphism) in intron 13 of the human gene encoding MAO-B. T he MAOB intron 13 allele status and levels of trbc-MAO were determined for 55 Caucasian non-smoking males. Individuals with the "A-allele" displayed significantly lower enzyme activi ty than individuals with the "G-allele" displayed significantly lower enzym e activity than individuals with the "G-allele" i.e. 11.4 +/- 0.6 nmol/10(1 0) platelets/min compared with 13.5 +/- 0.6 (mean +/- SEM, p = 0.019). The present results suggest that the MAOB genotype may be involved in deter mining trbc-MAO activity.