Trio (proband and parents) WES revealed novel compound heterozygous variants in TSFM [NM_001172696.2; OMIM 604723], a nuclear gene encoding a mitochondrial translation elongation factor (EF-T), that resulted in impaired mitochondrial biogenesis and respiratory function, leading to early-onset hypertrophic cardiomyopathy. Here, TSFM is linked to hypertrophic cardiomyopathy.