We have over 20,000 different genes in the body. These genes are like instruction manuals for how to build a protein, and each protein has an important function that helps to keep our body working how it should. The TPM1 gene makes a protein called the tropomyosin 1 (T1) protein. The T1 protein is most active in the heart and skeletal muscles (which help with movement) in our body. The T1 protein works with other proteins to create the force that is needed for our muscles to contract. This muscle contraction is how we move, and is how our heart pumps blood throughout our bodies.
If someone has a harmful change (called a pathogenic variant) in one of their TPM1 genes, then their body does not make as much T1 protein as it should. If there is not enough T1 protein, then the skeletal and cardiac muscles cannot contract as well as they should. This causes damage to these muscles, which can lead to several different types of health issues, such as familial hypertrophic cardiomyopathy, left ventricular noncompaction, and familial dilated cardiomyopathy.
Pathogenic variants in the TPM1 gene are passed through a family in an autosomal dominant pattern, meaning that anyone who carries the variant has a 50% chance to pass it down to any children they have. Women and men both have the TPM1 gene and have the same chances to inherit and pass down pathogenic variants.
Genetic testing for pathogenic variants in TPM1 is currently available, but there are a few different ways to approach testing: