In Cohort 1, the concentrations of adiponectin (median, 68.5 ng/mL vs 61.4 ng/mL; p<0.05) and leptin (median, 13.9 ng/mL vs 11.2 ng/mL; p<0.1) in mid-trimester AF were significantly higher in smaller compared with larger twins. The gene discussed is LEP; the disease is atrial fibrillation.