In another study that compared 845 healthy volunteers from four different Russian ethnic groups (238 Chuvash, 206 Marians, 157 Kabardians and 244 Ossetians) with another Russian population that comprised 400 atrial fibrillation patients, significant differences were identified in the CYP2C9*2 (ranging from 0.06 to 0.12), CYP2C9*3 (ranging from 0.07 to 0.14) and VKORC1 -1639G > A (ranging from 0.38 to 0.50) MAFs (Zotova et al., 2013; Mirzaev et al., 2020). This evidence concerns the gene CYP2C9 and atrial fibrillation.