ACE and migraine disorder: By investigating the common I/D polymorphism of the angiotensin I-converting enzyme (ACE) gene we found that the I/I genotype (associated with reduced ACE and angiotensin II serum levels, hence to reduced glutamatergic and increased GABAergic neurotransmission) seems to confer a milder migraine phenotype in patients with migraine with aura and chronic migraine[3].