• A mutation in MAOA results in a clinical phenotype characterized by borderline mental retardation and impaired impulse control [10].
• This study was conducted to detect a possible association of MAOA and/or MAOB genes with pathological gambling (PG) [11].
• Family-based association studies support a sexually dimorphic effect of COMT and MAOA on genetic susceptibility to obsessive-compulsive disorder [12].
• Monoamine oxidase A (MAOA) activity is altered in mood disorders and lower activity associated with aggressive behavior [13].
• Here, we investigated the influence of allelic variation of MAOA activity on aggression-related personality traits and disease risk in patients with personality disorders [14].

High impact information on MAOA

• Deficiency in monoamine oxidase A (MAOA), an enzyme that degrades serotonin and norepinephrine, has recently been shown to be associated with aggressive behavior in men of a Dutch family [15].
• A line of transgenic mice was isolated in which transgene integration caused a deletion in the gene encoding MAOA, providing an animal model of MAOA deficiency [15].
• In each of five affected males, a point mutation was identified in the eighth exon of the MAOA structural gene, which changes a glutamine to a termination codon [16].
• The anatomical distribution of 11C paralleled the distribution of MAO A and MAO B in human brain in autopsy material [17].
• A monoclonal antibody was used to prepare immunoaffinity columns that efficiently bind monoamine oxidase B activity but not monoamine oxidase A activity from detergent extracts of human liver mitochondria [18].

Chemical compound and disease context of MAOA

• The associations with the MAOA and serotonin transporter loci are consistent with previous data suggesting associations with susceptibility to bipolar affective disorder [19].
• Thyroid hormone receptor variants can cause attention deficit/hyperactivity disorder, and a monoamine oxidase A variant leads to aggressive behaviour in one family [20].
• We describe here four new monoclonal antibodies (designated MAO A-3C9, A-4F10, A-7B10, and A-7E10) which were elicited to highly purified MAO A from human placenta and which, in the presence of antimouse IgG and Staphylococcus aureus, immunoprecipitate greater than 90% of the catalytically active purified MAO A [21].
• Luciferase assays show that glucocorticoid (dexamethasone) and androgen (R1881) increase MAO A promoter and catalytic activities in human neuroblastoma and glioblastoma cells [22].
• A reversible monoamine oxidase A inhibitor (moclobemide) facilitates smoking cessation and abstinence in heavy, dependent smokers [23].

Biological context of MAOA

• The implications of fast acetylation, selective MAO inhibitors, types MAOA and MAOB, and measures of platelet MAO inhibition are discussed in this article [24].
• To examine whether this genetic variation might contribute to differences in brain activation within the anterior cingulate cortex, we genotyped 16 subjects for the DRD4 and MAOA genes who had been scanned during the ANT [25].
• Human MAOA and MAOB genes isolated from X chromosome-specific libraries span at least 60 kilobases, consist of 15 exons, and exhibit identical exon-intron organization [26].
• A maximal multipoint lod score of 3.69 was obtained at the monoamine oxidase type A (MAOA) locus in Xp11.23-11 [27].
• A pVNTR repeat polymorphism located in the promoter region of the X-linked MAOA gene has been associated with mental disorders [28].

Anatomical context of MAOA

• Turner phenotype was absent in group 4, including a fetus aborted at 21 wk gestation who preserved the region distal to MAOA [29].
• Association between monoamine oxidase A activity in human male skin fibroblasts and genotype of the MAOA promoter-associated variable number tandem repeat [30].
• Activities of both MAOA and MAOB were significantly increased in frontal cortex and caudate nucleus, two brain regions shown previously to be the site of functional and morphological alterations of astrocytes and increased concentrations of the acid metabolites of dopamine and serotonin [31].
• CONCLUSIONS: Central nervous system serotonergic activity correlates with human aggressive behavior and depression in many studies, and the MAOA promoter gene may also serve as a clinical marker in the treatment of cardiovascular disease [32].
• Telomeric length varies with age and polymorphisms of the MAOA gene promoter in peripheral blood cells obtained from a community in Taiwan [32].

Associations of MAOA with chemical compounds

• Exon 12 codes for the covalent FAD-binding-site and is the most conserved exon; the MAOA and MAOB exon 12 products share 93.9% peptide identity [26].
• Monoamine oxidases A and B [MAOA and MAOB; amine:oxygen oxidoreductase (deaminating) (flavin-containing), EC 1.4.3.4] play important roles in the metabolism of neuroactive, vasoactive amines and the Parkinsonism-producing neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) [26].
• Exon 12 (bearing the codon for cysteine, which carries the covalently bound FAD cofactor) and exon 13 are highly conserved between human MAOA and MAOB genes (92% at the amino acid level) [33].
• RESULTS: A suggestive association of sequence variations in genes responsible for the synthesis (TPH), recognition (5-HTR2A), and degradation (MAOA) of serotonin with depression symptomatology was found, although the effect was generally restricted to men [34].
• Noradrenaline (NA) is catabolized by monoamine oxidase A (MAOA) and cathecol-O-methyl transferase (COMT) [35].

Physical interactions of MAOA

• An X chromosome inactivation assay based on differential methylation of a CpG island coupled to a VNTR polymorphism at the 5' end of the monoamine oxidase A gene [36].

Enzymatic interactions of MAOA

• Additional studies revealed that MMPP was a poor substrate of only MAO B (Km,app = 9.5 mM) and that acid treatment of MMPP led to the formation of a product that could be readily oxidized by both MAO A and B. Similar acid pretreatment of TMMP yielded a product that was a much poorer substrate for MAO B than the parent compound [37].
• Human monoamine oxidase A and B genes map to Xp 11.23 and are deleted in a patient with Norrie disease [38].
• The CYP2D6 substrates bufuralol and debrisoquine showed strong inhibition of both tryptophol production from tryptamine in HLM and the formation of indole-3-acetaldehyde from tryptamine catalyzed by recombinant MAO-A [39].

Regulatory relationships of MAOA

• Cys5 and Cys266 were identified as the only residues modified by biotin-derivatized NEM in clorgyline-inactivated MAO A and pargyline-inactivated MAO B, respectively [40].
• Estrogenic control of monoamine oxidase A activity in human neuroblastoma cells expressing physiological concentrations of estrogen receptor [41].
• Specifically, there was a significantly lower rate of CCK-4-induced panic attacks in female subjects who had MAO-A longer alleles or 5-HTTLPR short allele gene variants [42].

Other interactions of MAOA

• All three complementary approaches employed (family-based, case-control and quantitative trait design) suggest a role for the MAO A promoter-region polymorphism in conferring risk for ADHD in our patient population [43].
• When comparing specific response to nonspecific response, we found significant negative associations in three SNPs in the HTR2A gene (P=0.001-0.03) and two SNPs in the MAOA gene (P=0.03-0.05) [44].
• Concentrations of MHPG in plasma are determined mainly by MAO-A activity because COMT inhibition did not have an additional effect on the moclobemide-induced decrease in plasma MHPG [45].
• In both cases, contingency table analysis revealed previously unreported gene-gene interaction between the MAOA and SLC6A2 genes (P=0.019 and 0.019, respectively) [46].
• In this study, we performed linkage analysis of MRX9 with a panel of 43 polymorphic DNA markers dispersed over chromosome X. Two-point linkage analysis revealed lod scores of 3.52 and 3.82 at 0% recombination for OATL1 and MAOA, both located in Xp11.2-p11 [47].
• In our sample, the effects of COMT on the release of adrenocorticotrophin hormone (ACTH) depend on the presence of the low-expression MAOA variant in the same individual [48].

Analytical, diagnostic and therapeutic context of MAOA

• Restriction mapping of the YAC indicates that it contains both MAOA and MAOB genes in addition to the DXS7 locus [49].
• Allelic mRNA expression of X-linked monoamine oxidase a (MAOA) in human brain: dissection of epigenetic and genetic factors [28].
• It has been shown from pulsed-field gel electrophoresis (PFGE) that the monoamine oxidase genes A and B (MAOA & MAOB) and DXS7 loci are physically very close [49].
• In total, 26.0% of cluster B patients were hemi- or homozygous for the low-activity variant of the MAOA genotype, compared to 16.4% in the control group [14].
• In the present study variations in the coding sequence of the MAOA gene were evaluated by RT-PCR, SSCP, and sequencing a mRNA or genomic DNA in 40 control males with > 100-fold variations of MAO-A activity, as measured in cultured skin fibroblasts [50].