GENETIC TESTING IN CHILDREN
There are over 30 different genes known to cause cardiomyopathy. Generally, in any one family with inherited heart muscle condition there is usually one faulty gene that is responsible for the condition; however occasionally there are two or more faulty genes identified as a cause of the cardiomyopathy.
Genetic testing is not widely available for the cardiomyopathies; however there are a number of centres which offer limited screening. If genetic testing is available to you, there are many things to think about before genetically testing your child. Some parents are keen to have their children tested while others have reservations.
Three of the most common concerns voiced by families are:
Can my child be genetically tested?
If the genetic fault is not already known in your family and your child is affected with a cardiomyopathy, then it is possible for your child to have a genetic test. This type of test is called a clinical genetic test. A positive result from a clinical genetic test could enable other family members to undergo a predictive test.
If the genetic fault is known in the family, then it is theoretically possible to genetically test your child. If your child is presently unaffected and you wish to test it for the presence or absence of this genetic fault, then it is called a predictive test.
Both types of tests require genetic counselling beforehand, either with a cardiologist or genetic specialist, so that you understand the benefits and limitations of the test. Unfortunately, if the genetic fault is not known in your family and your child is not affected and shows no sign of disease, then genetic testing is presently not possible.
What will happen if genetic testing is feasible and we decide we would like to have our child genetically tested?
Before your child is tested, a genetic counsellor will discuss with you the process of genetic testing so that as a family you can decide whether you wish to go ahead.
The counsellor will explore with both parent and child:
• how you will feel if the result is positive or negative
• the length of time it may take for a result
• how the result will be given to the family and follow-up agreement
• what will happen once the result is known
• implications for insurance, mortgages, careers and general lifestyle
If you agree to the genetic test, a blood test will be taken from your child. A local anaesthetic will be applied to his or her arm so the test will not hurt. You will be able to stay with your child.
What happens once the result is known?
Results from a clinical genetic test.
If your child is affected with a cardiomyopathy and has a positive genetic test, this means that the genetic cause of the cardiomyopathy has been identified. The genetic finding does not usually alter the treatment; however it allows for other family members to undergo predictive testing if they so wish.
Results from a predictive genetic test
If the genetic fault is known in your family and your child’s result is negative, then your child has not inherited the genetic fault and is no longer at risk of developing a cardiomyopathy in relation to the family history. In this instance, your child’s risk of developing cardiomyopathy becomes the same as that of the general population and they would not need to be screened routinely in the clinic.
If the genetic fault is known in your family and your child’s result is positive, then your child is at risk for developing a cardiomyopathy at some stage in its lifetime. Your child will require life long heart checks that are appropriate for the specific cardiomyopathy. Unfortunately, it is not presently possible to tell from a positive genetic test whether or not your child will go on to develop a cardiomyopathy, as some gene carriers may not develop symptoms in their lifetime. Due to this, it is recommended that your child is screened routinely within the clinic.
What happens if the genetic fault cannot be identified in the family?
It is not always possible to identify the genetic fault within a family. In this instance, affected family members and those at-risk family members should be under regular clinical review by a cardiologist.
Dedicated to Damian McLoughlin, who died age 20 of cardiomyopathy. This site is supported by Damian's family and friends.
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