Genetic testing is able to identify the abnormalities which are currently known to be identified in patients with hypertrophic cardiomyopathy. More and more gene abnormalities are being discovered. Approximately 60 to 70% of patients with known hypertrophic cardiomyopathy are felt to have a currently identifiable gene abnormality. These can be identified using the commercially available tests. The primary benefit of identifying genetic abnormality is to be able to help family members determine if they also have hypertrophic cardiomyopathy, or the gene responsible for it. If the individual has a gene identified, but the family member does not, that family member will not move to be further screened for hypertrophic cardiomyopathy in the future.
Although hypertrophic cardiomyopathy (HCM), also known as hypertrophic obstructive cardiomyopathy (HOCM) and idiopathic hypertrophic subaortic stenosis (IHSS), has been known about for a long time, the genes responsible have only recently been discovered in the last two decades. Worldwide efforts have seen over 1,000 gene mutations in more than 15 genes reported to date. Despite this, in about half of families, the gene responsible is not amongst those currently known. In addition, in as many as half of all patients, no prior family history is found.
Genetic testing is performed by outside laboratories specialized in cardiac genetics. While cost used to be high in the past, nearly all families can now get genetic testing with little or no cost. If the abnormal gene is found in one family member, then other family members find out if they will develop cardiomyopathy in the future by being tested specifically for that abnormal gene. Genetic counselors are available to help patients that are planning to have children.
Screening of relatives of patients with hypertrophic cardiomyopathy
Each patient with hypertrophic cardiomyopathy has a parent carrying the gene for hypertrophic cardiomyopathy even if the parent did not have symptoms or the diagnosis made. One of the patient’s grandparents also has the gene. There is a 50% chance that a patient's siblings or children will have the gene.
If the patient has genetic testing and a gene if identified, the family members just need to have genetic testing and no other testing is required unless a gene is identified in those individuals. If the patient has genetic testing but does not have a gene identified, the patient’s parent, siblings, and children should have regular electrocardiogram and echocardiogram testing. The current recommendations are that children have both these tests annually until puberty or age 18. After age 18, these tests may be taken every 5 years.
However, in every case of confirmed hypertrophic cardiomyopathy there is a 50/50 chance of passing the gene on to each member of the next generation, so family screening is very important. At the moment, most screening of family members is done using echocardiography and we are happy to coordinate this during your visit or liaise with physicians local to your family members. However, we also offer genetic counseling to our families.
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