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 MYBPC3 gene makes a protein called cardiac myosin binding protein C (MyBP-C). Our muscles, including our heart muscles, are made up of different fibers that help to control when our muscles contract. This process is necessary in our heart, because these contractions are how our heart pumps blood throughout our bodies. The cardiac MyBP-C protein works to keep these fibers in good working order so they can make sure our heart muscles are contracting how they should.
If there is a spelling error (called a mutation) in the gene (instruction manual) that makes this protein, then the protein that is produced may not be able to work properly. If this protein cannot do its job, then the fibers that control out heart contractions may get damaged. This can lead to the heart muscles becoming thin and weaker, along with the other symptoms that can be seen with hereditary heart disease.
Mutations in the MYBPC3 gene are passed through the family in an autosomal dominant pattern, meaning that anyone who carries a mutation has a 50% chance to pass it down to any children they have. There are different types of mutations that can affect the MYBPC3 gene. Some MYBPC3 gene mutations are responsible for 2-4% of all cases of familial dilated cardiomyopathy, while other mutations cause up to 30% of cases of familial hypertrophic cardiomyopathy. At least four specific mutations have been found to cause left ventricular noncompaction, which is when the left ventricle does not develop how it should.
Genetic testing for mutations in MYBPC3 is currently available, but there are a few different ways to approach testing: