Transcription Factor Activating Protein-2β (TFAP-2β) genotype and symptoms of attention deficit hyperactivity disorder in relation to symptoms of depression in two independent samples

The Transcription Factor Activating Protein-2 beta (TFAP-2 beta) gene has been shown to influence monoaminergic neurotransmission, and several genes important for monoaminergic function have binding sites for TFAP-2 beta. Familial studies of attention deficit hyperactivity disorder (ADHD) suggest a hereditary-determined subtype of ADHD with comorbid depression. We examined a functional variation of the TFAP-2 beta gene in the context of co-occurring symptoms of ADHD and depression in two independent population-based samples of adolescents (Group A, n = 175 and Group B, n = 1,506) from Sweden. Results indicated 6.1 to 7.8 % of adolescents screened positively for ADHD and depression symptoms. Symptoms of depression were more common among girls who screened positively for ADHD and did not carry the nine-repeat allele of the TFAP-2 beta intron 1 Variable Number Tandem Repeat (VNTR) polymorphism. The presence of the nine-repeat variant of the TFAP-2 beta intron 1 VNTR appears to protect girls with ADHD symptoms from the co-expression of symptoms of depression.