SFTPB and atrial fibrillation: mRNAs encoding surfactant proteins (SFTPA1, SFTPB, SFTPC, and SFTPD) and those involved in lipid synthesis and processing (LPCAT1, ABCA3, CTSH and LYZ), and regulation (FOXA2, NKX2-1, HOXA5) were increased with advancing gestational age in AF (Fig. 3a).