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 TNNI3 gene makes a protein called the cardiac troponin 1 protein. The cardiac troponin 1 protein is found primarily in the heart muscles in our body. The cardiac troponin 1 protein works with other proteins to create the force that is needed for our muscles to contract. This muscle contraction is how our heart pumps blood throughout our bodies.
If someone has a harmful change (called a pathogenic variant) in one of their TNNI3 genes, then their body does not make as much cardiac troponin 1 protein protein as it should. If there is not enough cardiac troponin 1 protein protein, then the heart 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, familial restrictive cardiomyopathy, and familial dilated cardiomyopathy.
Pathogenic variants in the TNNI3 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 TNNI3 gene and have the same chances to inherit and pass down pathogenic variants.
Genetic testing for pathogenic variants in TNNI3 is currently available, but there are a few different ways to approach testing: