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A cardiomyopathy is any disease that primarily affects the muscle of the heart. In HCM, the normal alignment of muscle cells is distrupted, a phenomenon known as myocardial disarray. HCM also causes disruptions of the electrical functions of the heart. HCM is believed to be due to a mutation in one of many genes that results in a mutated myosin heavy chain, one of the components of the myocyte (the muscle cell of the heart). Depending on the degree of obstruction of the outflow of blood from the left ventricle of the heart, HCM can be defined as obstructive or non-obstructive.
HCM is also known as idiopathic hypertrophic subaortic stenosis (IHSS) and hypertrophic obstructive cardiomyopathy (HOCM). A non-obstructive variant of HCM is apical hypertrophic cardiomyopathy 3, which is also known as nonobstructive hypertrophic cardiomyopathy and Japanese variant hypertrophic cardiomyopathy (since the first cases described were all in individuals of japanese descent).
While most literature so far focuses on European, American, and Japanese populations, HCM appears in all racial groups. The incidence of HCM is about 0.2% to 0.5% of the general population.
Hypertrophic cardiomyopathy is attributed to mutation in one of a number of genes that encode for one of the sarcomere proteinmyoglobin, showing coloured alpha helices. This protein was the first to have its structure solved by X-ray crystallography by Max Perutz and Sir John Cowdery Kendrew in 1958, which led to them receiving a Nobel Prize in Chemistry. A protein is a complex,s (usually effecting either the α or β myosinMyosin is a contractile protein filament found in muscle tissue. Together with actin filaments, myosin provides the mechanism for muscle contraction, utilizing energy from ATP. Muscle is composed of muscle cells (sometimes known as "muscle fibers"). Withi heavy chain on chromosome2) Centromere. The point where the two chromatids touch, and where the microtubules attach. 3) Short arm. 4) Long arm. A chromosome is, minimally, a very long, continuous piece of DNA, which contains many genes, regulatory elements and other intervening n 14 q11.2-3). While the severity of the disease process is dependant on the particular gene mutation, about 80% of cases are inherited in an autosomal dominantAn autosomal dominant gene is an abnormal gene on one of the autosomal (non-sex determining) chromosomes. Because it is dominant, it need only exist in the inherited chromosomes of one parent for it to cause disease. The chances of an autosomal dominant d pattern. Other gene mutations that are associated with HCM include mutations in α-tropomyosin (on chromosome 15), troponin T (on chromosome 1), and myosin-binding protein C (on chromosome 11). The prognosis is variable, based on the gene mutation.
The MYH7 gene (encoding the Β-myosin heavy chain) was the first specific gene identified in familial hypertrophic cardiomyopathy. About 50 percent of all familial cases involve mutation in the MYH7 gene. In individuals without a family history of HCM, the most common cause of the disease is also mutations of the gene that produces the β-myosin heavy chain. Many different mutations in this gene have been identified, and the prognosis is dependant on the particular mutation.
An insertion/deletion polymorphism in the gene encoding for angiotensin converting enzyme (ACE) has been associated with some cases of HCM. The D/D (deletion/deletion) genotype of ACE is associated with more marked hypertrophy of the left ventricle and may be associated with higher risk of adverse outcomes.8,9