What approach should be taken to minors requesting tests themselves? At what age can they give consent?

There have been increasing numbers of requests from young people themselves for testing. Binedell et alpropose an assessment approach to requests from adolescents for Huntington's disease (HD) prediction.5 These authors suggest four factors in particular which need consideration: an evaluation of the person's emotional, cognitive, and social maturity; ensuring that the person is acting autonomously; exploration of the role of the family context in the decision; and assessment of the person's experience and confidence in making major personal decisions. In addition, they highlight some particular factors of relevance, including the length of time that the adolescent has lived with the knowledge of HD in the family and his/her at risk status and the way that he/she coped with being informed about the risk.

At what age can a child give consent? In the recent UK survey, it was felt that the maturity of the child was more important than the specific age. Experience of living with the condition can be an important factor in understanding and IQ is not necessarily relevant. In the survey, 10 years was the most cited minimum age quoted by professionals for active involvement in the counselling process; 16 years was the most cited age for giving consent for predictive testing.4

Testing in a child who cannot give consent—the dilemma

From an ethical viewpoint, worries exist about possible long term psychological harm and the fact that testing removes the autonomy over decision making. Furthermore, the confidentiality to which an adult is entitled is breached by disclosing results to the parents, and testing the child breaches the policy of providing counselling to the person being tested before, during, and after the testing process. The concerns about removal of autonomy and confidentiality may be overridden by the responsibility to do what is in the best interests of the child. It is argued that we do not know what the best interests of the child are in the majority of genetic testing situations.6 The problem is that very few studies have assessed the short term effects and none have assessed the long term effects of testing for adult onset diseases.7

It is clearly appropriate to perform genetic testing of minors when the problem in question can be rectified, treated, or prevented but the decision is difficult when the risk from the test may be significant, the statistical risk of disease is minimal, and the benefit of early diagnosis is small. A variety of arguments have been put forward as potential benefits and these and the potential drawbacks are summarised in table 1. The use of a diagnostic test for the purpose of information seems highly problematic in the case of childhood testing and it is a controversial question as to whether reduction of parental anxiety by itself justifies testing when there is no clear or immediate medical benefit.8 From a legal viewpoint, McLean9argues that burdens should not outweigh benefits. She says that in the absence of convincing arguments to the contrary, it is necessary to err on the side of caution and not be overly willing to permit testing.

In any individual situation, deciding whether the burdens outweigh the benefits can be extremely difficult as exemplified in the debate about testing a newborn child for hypertrophic cardiomyopathy published in the British Medical Journal in 1995,10-12 and in the cases analysed by Chapple and colleagues.13 The most difficult situations arise in relation to adult diseases that can present in childhood (for example, adult polycystic kidney disease), childhood diseases that are not treatable or preventable, and carrier testing for autosomal andx linked recessive diseases or balanced chromosomal rearrangements.

The evidence

There is evidence from a variety of studies to suggest that being a carrier of a genetic disease can be associated with stigmatisation, discrimination, anxiety about future health, and loss of self esteem.14 Could this be potentially damaging if testing is performed as a child or could there be benefits from the information being gently introduced during the course of the child's development? A survey of parents in a cystic fibrosis clinic found that most wanted to know their children's carrier status and the large majority felt that it would not alter their child's upbringing—as the parents themselves are carriers, they should realise that being a carrier is not harmful.15

A few small retrospective studies have assessed the effects in those families where testing has been performed in childhood. Barnes performed a questionnaire study of 103 parents whose children had been tested for balanced chromosomal translocations (nearly 80% of whom had been tested prenatally) and found no obvious evidence of harm. This was based on a survey of the parents rather than assessments of the children. Nearly 78% of the children had not yet been informed of the result. None of the parents regretted having the children tested16 even though some parents had suffered considerable distress when finding out that their child was a carrier. Similarly, a Finnish study17 is looking at childhood testing in Xp21 dystrophies, haemophilia A and B, and translocations by questionnaires to parents and those children now over 15 years of age. Preliminary results indicate no psychological harm but many of the children had not heard the results or had misunderstood them.

Jolly et al assessed 10 families where children were tested for balanced translocations and where those children were now over 10 years of age.18 The children described their reactions to hearing the result of the test and these varied from initial shock and anxiety to calm acceptance. The effect depended to some extent on the family's experience. Some children experienced a phase where they had feelings of stigmatisation, consistent with the findings of Wolff et alin adults.19 Others experienced no more than a mild stigma, if any at all. Some experienced anxiety but this was transient. None of the children resented having been tested and some were glad that they had been tested when they were younger. The Genetics Interest Group's member societies have carried out small scale studies, including interviews with teenagers who were tested as children. These indicated that some who were tested would have preferred not to have been and some not tested would have preferred to have been. Thus, no general rule could be applied.20

Can we draw up any guidelines?

What is inappropriate?

• Nearly all agree that testing should not be performed in adult onset diseases where there is no treatment and where many adults decline testing, such as Huntington's disease. Sharpe has argued that it may be more harmful not to test in some situations (for example, parents misinterpreting behavioural problems as manifestations of HD. Could refusal to test in these circumstances result in a distortion of parent–child or sib–sib relationship?). He argues that parents are in a better position to decide than professionals.21 Such views are very much in the minority. It is an interesting exercise to consider what tests one might request oneself if given the option.22

• Testing would be very doubtful in those disorders with an adult onset where the genotype may not predict phenotype, even if a potential treatment is available, for example, haemochromatosis.23

• Testing is doubtful in those disorders with an adult onset even if there may be avoidable precipitants, for example, acute intermittent porphyria or thrombophilias (such as factor V Leiden, where female carriers might want to avoid the contraceptive pill). This can be encountered when reports from haematology laboratories identify carriers of thrombophilic mutations and suggest that other family members be tested, without any advice about the age at which testing is appropriate. Careful thought needs to be given to the wording of laboratory reports.

• At prenatal diagnosis, inadvertent carrier testing of females for X linked recessive disorders should be avoided.

• Commercial testing? The UK Advisory Committee on Genetic Testing considered the whole issue of testing supplied direct to the public, including the testing of children. In a report published in 1997, it concluded that these services should not be supplied to those under 16 years of age or those unable to make a competent decision regarding testing.24

• Susceptibility testing? Genes which confer susceptibility for complex disorders such as diabetes and coronary artery disease are now being discovered. It would be inappropriate to offer any testing for these genes unless there was a clear intervention that could be offered.

In terms of carrier testing, my view is to support the statements in the original CGS report1 where it was felt wiser to defer carrier testing for recessive disorders and balanced chromosomal rearrangements until the child is able to understand the issues and request testing in person, even though there is little current evidence to suggest that it is harmful. Most of the time, parents agree with this view but difficulties arise when one child has been tested inadvertently (for example, prenatally) and they feel it is appropriate for other children to then be tested. Further research is clearly required into the long term effects as, in a number of the surveys, the children were still unaware that they had been tested and it is of concern that some had misunderstood the results. In childhood onset disorders, testing need not be performed before the age at which health benefits accrue.

In those situations where it is deemed appropriate to offer presymptomatic testing or to test a child for carrier status, it is important for the paediatrician or geneticist to discuss the possible pros and cons of testing with the family so that a fully informed decision is reached. Follow up support and counselling should be available to the families, especially in the event of a positive test result and a clear arrangement made with the family to offer counselling to the child at appropriate stages in the future. The small studies so far performed indicate that some children have misunderstood their test results. A follow up arrangement should be made for those families where the decision is made not to test.