What role does genetics play in pediatric attention deficit hyperactivity disorder (ADHD)?

Updated: Nov 20, 2018
  • Author: Maggie A Wilkes, MD; Chief Editor: Caroly Pataki, MD  more...
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Answer

Family, twin, adoption, and segregation analysis, as well as molecular genetic studies, show that ADHD (ADD) has a substantial genetic component. Molecular genetic studies have revealed several genes that appear to be associated with ADHD (ADD) because of their effect on dopamine receptors, dopamine transport, and dopamine beta-hydroxylase.

Research by the NIHM has shown that variants of the gene for catecho-O-methyltransferase (COMT) are associated with different levels of prefrontal dopamine activity. COMT metabolizes dopamine.

People with the val/val variant metabolize dopamine rapidly. Because fast metabolism of a substrate decreases the amount of substrate that is biologically available, these people have reduced prefrontal dopamine activity. This reduction, in turn, impairs prefrontal information processing.

Individuals with the val/met variant have fairly efficient prefrontal function.

Patients with the met/met variant have the most efficient prefrontal function. In fact, this variant results in an enzyme that is 3-4 times weaker than the product of the val/val variant.


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