A positive association was found between severe headache or migraine and high serum folate levels in a nationally representative US population, after adjusting for various confounding factors including sex, age, race, marital status, socioeconomic status, education level, hyperlipidemia, alcohol consumption, smoking status, BMI, Hcy, CRP, folate acid supplementation, and serum vitamin B12 levels. The gene discussed is CRP; the disease is migraine disorder.