Genetic Variants as a Potentially Arrhythmogenic Substrate in Mitral Annular Disjunction: Case Report and a Systematic Review of the Literature

Mitral annular disjunction (MAD) is associated with an increased risk of ventricular arrhythmias and sudden cardiac death, yet its genetic background remains poorly defined. We report the case of a 50-year-old man with MAD who survived cardiac arrest and carries three variants of unknown significance (VUS) in genes involved in cardiomyopathy pathogenesis. To explore the genetic basis of non-syndromic MAD, we performed a systematic review of the literature, identifying five case reports and one retrospective cohort study. The case reports described patients with MAD harboring four pathogenic variants and ten VUS. Two pathogenic variants were linked to cardiomyopathies, involving proteins of the nuclear envelope and cytoskeleton, while two were associated with channelopathies. The retrospective cohort study identified a recurrent variant in a gene involved in intercellular adhesion segregating within a family affected by MAD. Overall, available evidence suggests that genetic factors may hypothetically modulate susceptibility to MAD, not only in connective tissue disorders but also in isolated mitral valve disease. Variants associated with arrhythmogenic cardiomyopathies and channelopathies appear to cluster in families with non-syndromic MAD and arrhythmic phenotypes, suggesting a role in the arrhythmic substrate. However, in absence of definitive functional, segregation, or longitudinal data, the contribution of genetic variants to MAD should be interpreted with caution. Further genomic studies are needed to clarify their genetic contribution and prognostic implications.