Mitral annular disjunction (MAD) is supposed to be the anatomic substrate of mitral valve prolapse (MVP) and ventricular arrhythmias, whereas little is known about its molecular genesis, if any. Herein, we conducted the initial genetic screening among sporadic and familial MAD cases. Our findings supported that longitudinally extensive MAD, rather than MAD with any distance, tended to be a genetically-predisposing phenotype. We also reported the first case that a mutation in DCHS1 co-segregated with familial MAD independent of MVP. The current study might expand the knowledge regarding the relationship between MAD and MVP, facilitating risk stratification and genetic counselling for these patients. (By Nan ZHOU MD.,PhD., https://jmg.bmj.com/content/early/2023/06/29/jmg-2023-109278 )