Relationship Between Platelet Monoamine Oxidase B Activity and Alleles at the MAOB Locus

: Genetic variations in monoamine oxidase (MAO)‐B activity have been proposed to have a contributory role in several neurologic and psychiatric diseases. Variations in activity could affect rates of degradation of exogenous amines, including toxins, precursors of toxins (like 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine), or false transmitters, and of endogenous amines, such as neurotransmitters. In this study a highly polymorphic (GT)n repeat element was used to mark alleles at the MAOB locus. The MAOB allele status and levels of platelet MAO‐B activity were determined for 41 control males. No correlation was noted between specific alleles and levels of MAO‐B activity in this sample set. This suggests that the structural gene for MAOB is not usually the primary determinant of activity levels in platelets.