The genetics of chronic headaches.

Patients with chronic daily headaches (CDH) bear similarities to drug or substance abuse patients, for whom genetic liability loci have been implicated. We reviewed papers dealing with the metabolic and the genetic aspects of CDH. The relative risk for CDH in first-degree relatives is 2.1- to 3.9-fold increased compared to the general population. Genetic variation at the dopamine receptor 2 has been associated with co-morbidity of migraine with aura with major depression and anxiety, and allele D of the angiotensin converting enzyme increases the frequency of migraine without aura attacks. In CDH, analgesic abuse was significantly associated with specific functional polymorphisms at the DRD 4 and at the dopamine transporter (DAT) genes, findings implicating dopamine-related genes in CDH with drug abuse. CDH carries a substantial genetic predisposition. Molecular genetic studies are, however, still few and preliminary.