RPS4Y1 and atrial fibrillation: All genes with increased expression in AF samples of women with a male fetus compared to those with a female fetus, were located on the chromosome Y (q < 0.05, OR = 64, Additional file 4: Figure S4), with ribosomal protein S4, Y-linked 1 (RPS4Y1) being the most increased in pregnancies with a male fetus (8-fold increase) (Additional file 16: Table S10).