Studies of MAOA genotypes (type 1 with at least one short allele 3, type 2 with only the long alleles 3.5, 4 or 5) in depressive patients and controls found that females with major depression had significantly higher frequencies of MAOA type 2 than that in female healthy controls, while no differences were found in MAOA type 1 between depression patients and controls regardless of genders [22]. This evidence concerns the gene MAOA and depressive disorder.