Association of Monoamine Oxidase A Gene Promoter Region (30 bp μVNTR) Polymorphism with Serum Levels in Multiple Psychiatric Disorders

<b>Background:</b> Monoamine oxidase A (MAOA) has a role in metabolising different biogenic amines, including dopamine. Functional studies have revealed the effect of promoter region variants on the transcriptional activity of the <i>MAOA</i> that consequently affects the homeostasis of the biogenic amines which might implicate in the aetiology of multiple psychiatric conditions. <b>Objectives:</b> The current study aimed to determine the influence of the promoter region 30 base pair (bp), a variable number of tandem repeats (VNTR) of the <i>MAOA</i>, on its serum levels and association with schizophrenia (SHZ), bipolar disorder (BD), and major depressive disorder (MDD) in the Pakistani population. <b>Methods:</b> A total of 1062 subjects [MDD <i>n</i> = 416, BD <i>n</i> = 200, SHZ <i>n</i> = 97 and controls <i>n</i> = 349], were genotyped for <i>MAOA</i>-30bp µVNTR through standard polymerase chain reaction technique and logistic regression was applied to determine the genetic association. Serum MAOA levels were determined through enzyme-linked immunosorbent assay (ELISA) and the Mann-Whitney U test was applied. <b>Results:</b> In genotype analysis, eight different repeat (R) alleles of <i>MAOA</i>-30 bp µVNTR were observed, where 4.5R, 5.5R, and 6R were the rare repeats found in the current Pakistani cohort. In serum-based analysis the total MAOA serum levels were found to be significantly elevated in SHZ; however, in sub-group analysis, significantly higher serum levels of MAOA were observed only in the rare allele groups of MDD, BD, and SHZ. <b>Conclusions:</b> The current study gives us further insights into the complex nature of <i>MAOA</i> regulation and its genetic and serum-levels association with different psychiatric conditions.