Letter to the Editor

To the Editor; We would like to comment on Duncan and Chodirker's excellent commentary on the use of complete genomic hybridization (CGH) in Canada. We are concerned that this brief article did not adequately address the many ethical concerns associated with the use of this powerful technique including the following: CGH often reveals minor DNA anomalies that are of uncertain significance, leaving a child labelled with a DNA anomaly, but with no idea whether it is of medical importance. CGH may reveal significant DNA anomalies that are not related to the condition being investigated; these unrelated DNA anomalies may have implications for the future health of the child. Finding DNA anomalies in the infant will often lead to the parents being tested. This testing may reveal that they also carry the DNA anomaly, which may have implications for the parents' future health or may impact their insurability. Because CGH is often performed when the diagnosis is uncertain, it is impossible to counsel parents regarding potential implications of the hundreds of possible diagnoses that might follow, or the potential future health impacts. CGH may reveal DNA anomalies that could affect (or will, in the future, be shown to affect) the health status of the infant including risks of cardiovascular disease or cancer risks. The most worrisome concern is that CGH may reveal DNA anomalies that are associated with an increased risk of future mental health or behaviour problems, but with what is referred to as ‘reduced penetrance’, ie, they are not very specific (1). How can we (and do we currently) counsel parents that the CGH test we are performing might reveal that their child has an increased risk of future antisocial behaviour, bipolar disorder and schizophrenia, but that even if their child has the relevant microdeletion, the occurrence of these problems is not certain, and we cannot do anything to prevent them anyway? CGH results provide a permanent record of DNA anomalies, and the test is performed on an infant who is unable to understand or consent. Because of the above considerations, mechanisms must be in place to inform the infant that such a record exists, at an age when they are able to understand and decide whether they wish to be informed of the results. Although many other medical investigations carry the ‘risk’ of diagnosing unexpected disorders (even a complete blood count for evaluating anemia may lead to a diagnosis of leukemia), the unique risks associated with CGH include lifelong implications for the baby when diagnosed with an untreatable DNA anomaly (2). In clinical ethics, we speak about the right not to know certain medical information (3–5). It seems clear that under certain circumstances, neonates and parents are often better off not knowing and that some, if they were able to give fully informed consent, would choose a karyotype test over CGH for their neonates. This is not the first time in medicine that a new technique has been introduced before the ethical framework for its use has been established; perhaps it is even the norm. However, we believe that before the use of CGH as a first-line investigation becomes widespread, these ethical issues need to be discussed and guidelines developed. Millions of dollars are invested in CGH research; unfortunately, this research does not include the psychological effects of this testing on neonates and their families as they mature. Informed consent requires that parents receive the information and are counselled about the risks and benefits, followed by a determination of whether they understand, as well as the offer of an alternative if one exists. Are the risks and benefits of CGH mentioned to parents? Do parents really understand the lack of specificity of the investigation, and the sensitivity for findings of uncertain significance? Parents should be informed that there are alternatives to a shotgun CGH. We believe that the following alternatives should be proposed and discussed with parents: Karyotype test when there is a potential diagnosis that could be revealed. Karyotype test now, with the option of CGH in the future depending on the evolution of the case and parental desires. CGH, with parents only being informed of results that are of known significance for the precise condition that is being investigated, and maintenance of the remainder of the findings in a secure database for future use by the patient should they desire. Shotgun CGH with reporting of all the findings, after complete parental informed consent, covering all of the issues enumerated above.

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