Genetic Testing for HCM
HCM is the most common genetic heart abnormality.
One in 500 Americans are diagnosed with HCM, yet because this condition often goes undiagnosed.
HCM is autosomal dominant condition, meaning that individuals have a 50% chance of inheriting, or passing on, the predisposition to this disorder to their children.
To date, we have identified several hundred mutations affecting more than 15 genes associated with HCM. Children have mutations in at least 30 different genes associated with HCM.
Genetic testing can be done from a blood sample. It is important for two reasons: patients can find out more about their own prognosis, and learn if family members, who have so far shown no signs of HCM, are at risk of developing the condition in the future.
Until recently, the only way to screen family members for HCM was through a yearly echocardiogram. Today, genetic testing is the standard. This is a cost-effective way to find out which relatives need to be followed and which individuals no longer have to be concerned about developing HCM.
Sometimes the gene can also tell us if patient is likely to develop electrical abnormalities or arrhythmias and can also indicate if a person is at risk for sudden cardiac death. (While this risk of SCD is roughly 5% at adolescence, this tapers off with age. Only 1% of all patient with HCM are at risk for SCD.)
Finally, genetic testing can help in family planning. If only one parent tests positive for a HCM gene, the mutation can be passed on to the next generation.
Some couples opt for prenatal genetic testing for HCM while others opt for in vitro fertilization with genetic testing for HCM before the embryo is implanted in the womb.
Women with HCM may not be able to carry a child; these individuals may choose to genetically test prior to implanting the embryo in a surrogate.
Our genetic program has counseled over 800 HCM patients to date. We begin with an educational session, explaining what the testing will reveal and how family members will benefit from this knowledge.
Many patients come to us after there has been a sudden death in the family. We work with medical examiners all across the country, and do post-mortem testing for HCM when necessary.
If an autopsy confirms the diagnosis of HCM, we can counsel the entire family. As genetic detectives, we figure out who is at risk and needs to be followed closely. Family members who don't carry the gene are not only relieved of worry, they are also spared the expense of repeated monitoring and medical tests.
Genetic testing is either covered in full by most insurance policies or the patient has a maximum out-of-pocket cost of $100. Once we send the sample to the lab, we have results within 8 weeks. In this time, the lab may complete as many as 15 different tests.
How does this testing work? From a blood sample DNA, or genetic material, is isolated. The genes most commonly responsible for HCM are read like words on a page. We are looking for a typo or misspelling that causes a mistake in the protein made by that gene.
The same gene mutation can also manifest itself at different ages within a single family, and not everyone with the genetic predisposition will develop HCMA. For example, a newborn may have severe HCM, her father may have been diagnosed in his 20s, and the grandfather may have a completely normal echocardiogram.
We are presently engaged in clinical research to find out how we can help future generations who are genetically at risk for HCM.
The advantage of coming to the HCM Center at NewYork-Presbyterian is that we're not just satisfied with today's answers. We are looking for tomorrow's answers too.