MAO A VNTR polymorphism and amygdala volume in healthy subjects

Abstract

The X-linked Monoamine Oxidase A (MAO A) gene presents a well known functional polymorphism consisting of a variable number of tandem repeats (VNTR) (long and short variants) previously associated with altered neural function of the amygdala. Using automatic subcortical segmentation (Freesurfer), we investigated whether amygdala volume could be influenced by this genotype. We studied 109 healthy subjects (age range 18-80 years; 59 male and 50 female), 74 carrying the MAO A High-activity allele and 35 the MAO A Low-activity allele. No significant effect of the MAO A polymorphism or interaction effect between polymorphism × gender was found on amygdalar volume. Thus, our findings suggest that the reported impact of the MAO A polymorphism on amygdala function is not coupled with consistent volumetric changes in healthy subjects. Future studies are needed to investigate whether the association between volume of the amygdala and the MAO A VNTR polymorphism is influenced by social/psychological variables, such as impulsivity, trauma history and cigarette smoking behaviour, not taken into account in this work.

Association of monoamine oxidase-A genetic variants and amygdala morphology in violent offenders with antisocial personality disorder and high psychopathic traits

“…At least one study found that MAOA-L carriers display reduced amygdala volumes bilaterally relative to MAOA-H carriers 15 . By contrast, another investigation reported no difference in amygdala volume by MAO-A genotype 26 . The wide age range (18–80 years) of the second sample compared with the younger age of the participants tested in the first study was suggested as one reason for the discrepant results.…”

Sex differences modulating serotonergic polymorphisms implicated in the mechanistic pathways of risk for depression and related disorders:

“…Amygdala activity during emotional face-matching increases with childhood stress in male MAOA-L carriers and decreases with childhood stress in male MAOA-H carriers, with the reverse holding in females (Holz et al, 2016). Amygdala volume, however, was not affected by MAO-A genotype or an interaction effect between genotype and sex (Cerasa et al, 2011). Increased hippocampal activity (Meyer Lin-denberg et al, 2006) and dysregulated vmPFC (Buckholtz et al, 2008) were observed in MAOA-L males but not females (see Figure 1).…”

The neuroanatomical correlates of anxiety in a healthy population: differences between the State‐Trait Anxiety Inventory and the Hamilton Anxiety Rating Scale

“…The automated procedures for volumetric measures of several deep GM structures have been previously described (Cerasa et al 2011; Fischl et al 2002). This procedure automatically provided segments and labels for up to 40 unique structures and assigned a neuroanatomical label to each voxel in an MRI volume based on probabilistic information estimated automatically from a manually labeled training set.…”