The CYP2D6*4 allele defined by rs3892097 (splice defect) occurred at a significantly lower frequency (1.7%) in the SSA populations in this study compared with the frequency in European populations (AF = 11.8%) and was also less frequent than the estimated average frequency from previous studies in SSA (P = 0.0002; Table2). This evidence concerns the gene CYP2D6 and atrial fibrillation.