1.1.3 Genetic testing of children
Within clinical genetic services, a difference has grown up between the testing of children and the testing of adults. Sometimes the genetic testing of children is relatively uncontroversial. For example, the genetic test may simply be to confirm a medical diagnosis that has been made on clinical grounds. So a three-year-old with low weight, blocked lungs and poor digestion may be given a genetic test to see whether they have CF or not.
There are other cases where a test is used predictively for a disorder that may affect the child soon and which needs observation. For example, in a family where the dominant disorder familial adenomatous polyposis coli (FAP) is present, there is an increased risk of bowel cancer. Medical surveillance for tumours, which can be removed if diagnosed early, is often started at about 10 years of age. Pre-symptomatic testing of children to determine whether they carry the FAP gene, and hence need to be monitored, makes sense.
But we can contrast such a straightforward case of predictive testing with genetic tests for a disorder like Huntington's disease (HD), a late onset (over 40 years of age) neurological disorder, for which there is no cure, and only limited treatment. Now that a test for the gene responsible for HD is available, should children be tested?
SAQ 4
What do you think are some of the arguments against testing a child for HD?
Answer
Some that you may have thought of are: (i) testing a child prevents them making a future decision for themselves when they are an adult; (ii) confidentiality, important in the case of adult genetic test results, will be automatically overridden in the case of a child brought in for testing by his/her parents; (iii) family knowledge of the test's result might lead to a child being treated differently by his/her parents and siblings, because they might be brought up with lower expectations of themselves.
Adult uptake of the HD test has been far lower than predicted. When asked hypothetically if they would take the test, a clear majority of at-risk adults said ‘yes’: now that the test is available, only 10–15% have actually gone for testing. Hypothetical decisions about genetic testing, either for oneself or (by extension) one's children do not seem adequately to represent real attitudes to tests when they are offered.
When people request genetic testing for their children, they usually make assumptions about what the child would want if they were older, and that the information gained from a test will be of benefit to the child concerned. On the basis of previous testing programmes, neither of these points seems valid. The bottom line is that problems in adult testing for Huntington's disease seem to arise not in the context of testing, but that of the counselling session, the provision of information and the comprehension and implications of risk estimates. These problems are going to be magnified in the case of testing children.