Formin Homology 2 Domain Containing 3 (FHOD3) Is a Genetic Basis for Hypertrophic Cardiomyopathy

J Am Coll Cardiol. 2018 Nov 13;72(20):2457-2467. doi: 10.1016/j.jacc.2018.10.001.


Background: The genetic cause of hypertrophic cardiomyopathy remains unexplained in a substantial proportion of cases. Formin homology 2 domain containing 3 (FHOD3) may have a role in the pathogenesis of cardiac hypertrophy but has not been implicated in hypertrophic cardiomyopathy.

Objectives: This study sought to investigate the relation between FHOD3 mutations and the development of hypertrophic cardiomyopathy.

Methods: FHOD3 was sequenced by massive parallel sequencing in 3,189 hypertrophic cardiomyopathy unrelated probands and 2,777 patients with no evidence of cardiomyopathy (disease control subjects). The authors evaluated protein-altering candidate variants in FHOD3 for cosegregation, clinical characteristics, and outcomes.

Results: The authors identified 94 candidate variants in 132 probands. The variants' frequencies were significantly higher in patients with hypertrophic cardiomyopathy (74 of 3,189 [2.32%]) than in disease control subjects (18 of 2,777 [0.65%]; p < 0.001) or in the gnomAD database (1,049 of 138,606 [0.76%]; p < 0.001). FHOD3 mutations cosegregated with hypertrophic cardiomyopathy in 17 families, with a combined logarithm of the odds score of 7.92, indicative of very strong segregation. One-half of the disease-causing variants were clustered in a small conserved coiled-coil domain (amino acids 622 to 655); odds ratio for hypertrophic cardiomyopathy was 21.8 versus disease control subjects (95% confidence interval: 1.3 to 37.9; p < 0.001) and 14.1 against gnomAD (95% confidence interval: 6.9 to 28.7; p < 0.001). Hypertrophic cardiomyopathy patients carrying (likely) pathogenic mutations in FHOD3 (n = 70) were diagnosed after age 30 years (mean 46.1 ± 18.7 years), and two-thirds (66%) were males. Of the patients, 82% had asymmetric septal hypertrophy (mean 18.8 ± 5 mm); left ventricular ejection fraction <50% was present in 14% and hypertrabeculation in 16%. Events were rare before age 30 years, with an annual cardiovascular death incidence of 1% during follow-up.

Conclusions: FHOD3 is a novel disease gene in hypertrophic cardiomyopathy, accounting for approximately 1% to 2% of cases. The phenotype and the rate of cardiovascular events are similar to those reported in unselected cohorts. The FHOD3 gene should be routinely included in hypertrophic cardiomyopathy genetic testing panels.

Keywords: FHOD3; cardiomyopathies; formins; genetics; hypertrophic cardiomyopathy; sudden death.

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Cardiomyopathy, Hypertrophic / diagnosis*
  • Cardiomyopathy, Hypertrophic / genetics*
  • Child
  • Cohort Studies
  • Female
  • Follow-Up Studies
  • Formins
  • Genetic Variation / genetics*
  • Humans
  • Male
  • Microfilament Proteins / genetics*
  • Middle Aged
  • Mutation / genetics*
  • Pedigree
  • Young Adult


  • FHOD3 protein, human
  • Formins
  • Microfilament Proteins