Migraine is the most common type of chronic, episodic headache, affecting 10%-12% of the adult population. It is more prevalent among women, and, for both sexes, it develops in the second and third decades and often persisting into late middle age, but declines thereafter. Two primary types of migraine can be distinguished: migraine without aura (MO) and migraine with aura (MA). MO, the most common form of migraine, is characterized by unilateral pulsating pain of moderate to severe intensity, aggravated by physical activity and lasting 4 -72 h. The attacks are associated with nausea, vomiting, photophobia, and phonophobia. MA shares the same headache qualities, but the headache attack is usually preceded by transient focal neurological aura symptoms, usually visual, that develop gradually within 5-20 min and that persist for <60 min. Frequency, duration, and severity of the attacks vary substantially among patients and also in the same patients. Moreover, approximately one-third of individuals with migraine experience both types of migraine during their lifetimes, but usually one type of attack prevails.
Although the pathophysiology of migraine remains largely unknown, there are clearly genetic, vascular and neural mechanisms involved. Migraine episodes are frequently triggered by several factors like emotional stress, hypoglycemia, lack of or excessive sleep, certain foods, hormonal changes in women, sensorial stimulation (loud noise, light, strong odor) and sympathetic stimulation (sport, physical exercise). The diagnosis is based on clinical criteria, since biochemical or instrumental tests are not available. Symptoms can be difficult to control and quality of life may deteriorate substantially. Management includes modification of diet, and recommendations for sleep, exercise, and stress reduction through bio-behavioral interventions as well as the use of a range of medications for prevention and acute treatment of migraine.
Family-, twin-, and population-based studies strongly suggest that both genetic and environmental factors are involved in the two types of migraine, most likely with a multifactorial mode of inheritance, but that genetic factors are more influential in MA than in MO. The inheritance of migraine is estimated between 34-57%. Moreover, approximately 50% of migraine sufferers have an affected first-degree relative. Despite that, the mode of transmission of the disorder is not clear. However, in some families, a Mendelian pattern of inheritance cannot be excluded.
Migraine exhibits genetic heterogeneity. Multiple loci have been identified for both MA and MO (MGR1- MGR12). Familial hemiplegic migraine (FHM), which is a type of autosomal dominant MA, has been known to occur due to mutations in the CACNA1A (Calcium Voltage-Gated Channel Subunit Alpha1 A) gene, ATP1A2 (ATPase Na+/K+ Transporting Subunit Alpha 2) gene, and SCN1A (Sodium Voltage-Gated Channel Alpha Subunit 1) gene. Additionally, variations in the ESR1 (Estrogen Receptor 1) gene, and TNF (Tumor Necrosis Factor) gene has been reported to confer susceptibility to migraine.