Monoamine oxidase A polymorphism in Brazilian patients - Risk factor for late-onset Alzheimer's disease?

Different studies have attempted to find polymorphisms involved in the serotonergic pathway that could be involved in mood disorders and late-onset Alzheimer's disease (LOAD) symptoms. Here, we compared the frequency of two polymorphisms: monoamine oxidase A (MAOA) and serotonin transporter in LOAD patients versus controls. No evidence of association was observed when these polymorphisms were compared separately; however, the combination of the MAOA allele 1 + the short allele of 5-HTTLPR + ApoE-epsilon 4 was significantly more frequent in patients than in controls. It reinforces the hypothesis that different genes acting together might play a role in AD susceptibility. Based on these data, we suggest replicating these studies in larger samples of LOAD patients belonging to different ethnic groups.