Successful pregnancy and delivery in a young-onset hypertrophic cardiomyopathy patient with a novel doublet-base substitution in the MYH7 gene.

UNLABELLED: Herein, we report the case of a young-onset female hypertrophic cardiomyopathy (HCM) patient with severe left ventricular outflow tract obstruction who had a family history of premature sudden cardiac death. Despite the severe HCM phenotype, the patient was successfully managed by low-dose bisoprolol during two peripartum periods after a percutaneous transluminal septal myocardial ablation.We performed whole-genome sequencing analysis and found a novel doublet-base substitution (DBS) in the MYH7 gene (c.2608_2609delinsTT, p.R870F) in this patient. Her children were also genetically tested after careful genetic counselling to their parents, and one of her children at 1-year-old with left ventricular hypertrophy was found to have the same gene mutation. The location of the DBS in a functionally important domain and the inheritance of the same mutation in the offspring with the HCM phenotype suggested that this mutation in the MYH7 gene was responsible for the severe HCM phenotype. Proactive genetic testing would provide beneficial information for appropriate follow-up and initiation of therapy in children with possibly pathogenic gene mutations; however, revisions of genetic counselling may be considered according to their growth.

LEARNING

OBJECTIVE

Hypertrophic cardiomyopathy (HCM) patients with severe left ventricular outflow tract obstruction are at a high risk of hemodynamic deterioration during pregnancy. Preceding myocardial ablation therapy and a careful medical management during peripartum period may enable safe pregnancy and delivery in severe obstructive HCM patients. A novel doublet-base substitution in the MYH7 gene (c.2608_2609delinsTT, p.R870F) was found as a likely pathogenic mutation of young-onset severe HCM.