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The Gene Scene: MYL3
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The Gene Scene: MYL3

Frankie Fann, MS, CGC
September 15, 2026
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Your weekly snapshot of clinically actionable genes from the ACMG Secondary Findings List.

Clinical Phenotype Summary:

The MYL3 gene (NM_000258.2), which contains 6 coding exons and is located on chromosome 3p21.31, encodes the myosin light chain 3 protein. Pathogenic variants in this gene are known to cause MYL3-related cardiomyopathy, which is inherited in an autosomal dominant fashion. MYL3-related cardiomyopathy primarily presents as hypertrophic cardiomyopathy (HCM), which is defined by increased septal or posterior wall thickness, often leading to:

  • early onset syncope
  • ventricular fibrillation
  • episodic chest pain
  • dyspnea
  • cardiac arrest

Other cardiomyopathy types have also been described. 

Unique Considerations:

  • Mechanism of disease is unclear for MYL3-related cardiomyopathy.
  • Reduced penetrance and variable expressivity have been reported.

Clinical Resources:

Ambry Knows Genes:

Peer-Reviewed Publications:

Scientific Posters:

Citations:

Ambry Genetics Gene-Disease Validity Scheme

Each week, we explore a gene from the ACMG Secondary Findings list—genes identified by the American College of Medical Genetics and Genomics as having clear, actionable health implications. These genes are included because they’re linked to serious but preventable or manageable conditions when identified early.

To learn more about the ACMG Secondary Findings list, click here.

To read all previous Gene Scene emails, click here.