Clinical Genetics Society

Clinical Governance Subcommittee

Paper 4 (Version A, 5/7/2001) Protocols For Pre-Symptomatic (Predictive) Testing For Late Onset Genetic Disorders.

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Introduction

The diseases included in this category are single gene disorders such as Huntington disease, or a Mendelian sub-set of common cancer such as familial polyposis coli (FAP), hereditary non-polyposis colorectal cancer (HNPCC) and breast cancer (BRCA 1 and 2).

Guidelines for the molecular genetics predictive test have been developed for Huntington disease¹.  Similarly, guidelines have also been developed for familial breast cancer, BRCA1 and BRCA2 gene testing.  In the case of bowel cancer, two types of protocols currently exist, an extended one, based on Huntington disease protocol, and a shortened one currently being piloted⁴.

The rational for such protocols

1.      The aim and main purpose is the client-led exploration of the decision concerning testing.

2.      Distinct from diagnostic testing, pre-symptomatic testing for late onset disorders achieves a change in knowledge about self, sometimes in the absence of effective treatments.  Therefore, psychological components of the decision, such as reactions and adaptations, are arguably the predominant elements of pre-symptomatic testing¹.

3.      Models were developed to provide an outline structure to assist clinicians in facilitating the decision-making process and preparing candidates for a genetic pre-symptomatic test result.  Clinicians need to be clear about their roles and aims while conducting these interviews.  Solden et al suggest that this model worked well for Huntington disease, but for other "common" disorders, this model can be used for guidance, but for each disease, the different aspects will need re-prioritising, and new considerations may need to be incorporated.  In breast cancer, for example, the different public perceptions of the condition and how individual deals with uncertainty may be an important additional variable to explore with those requesting breast cancer susceptibility testing.

Aims of pre-symptomatic testing

Evaluation of the current and developing models is needed and is still mostly awaited, but authors have recognised the need to promote:

1.      Adaptation to a result

2.      Informed decision making

3.      Client-centred focus

4.      The uniqueness of the individuals experience.

5.      The working through of experiences at the candidates' own pace, and in their own way

 

The process of pre-symptomatic testing interview has been described as²:

Clarification ® consideration®  education ®  reflection ®  decision making ® drop out/result

1.      Clarification of candidate's understanding of the disease and testing

2.      Consideration of the potential impact and available coping strategies

3.      Education using factual information about the disease and testing, impact of the result, stress and coping, coping resources and strategies

4.      Reflection to help individual to assess whether they have the resources to cope with their potential psychological reaction.

5.      Decision-making is a process, typically occurring outside the counselling context.

 

Essential elements of a pre-symptomatic testing protocol

There is a significant deficiency in evidence upon which to base guidelines.  Research projects must address this deficit.  Our suggestions for best clinical practice, to achieve the aims outlined above include:

a.       Pre-test information - either verbal or supplemented by written information.  The latter may cut sessions down from 2 to 1 in some disorders.

b.      At least one face to face pre-test counselling session to facilitate clarification, consideration and reflection.

c.       A consideration of time for client reflection in any protocol.

d.      Face to face meeting for result giving, to allow response to questions and support for emotional distress.

e.       Follow-up protocols in place to give support and identify any adverse effects.

f.        Clinician review of each test result.

 

Conclusions

1.      Guidelines for Huntington disease have served the patients, their families and the professionals involved in the delivery of the service, very well over several years.  They remain very useful guidelines.

2.      Guidelines for breast, ovarian and bowel cancer.

2.1.   Full adoption of Huntington's guidelines may not be appropriate.  Differences exist, as described below.

2.2.   Unlike Huntington disease, there are preventive surgical &/prophylactic treatment available that may reduce the risk of breast, ovarian and bowel cancer. 

2.3.   A period of one month contemplation prior to testing may not be necessary; a shorter period may felt to be sufficient by some workers in some circumstances. 

2.4.   While geneticists in some centres give all results, it may not always be practical or feasible in a cancer situation.

2.5.   The requirement of a formal psychological appraisal prior to testing is uncertain.  Further research is needed.

3.      Most of the steps required for Huntington disease PST can be viewed as best practice guidelines for all genetic disorders, if adequate resources are available.  While curtailing them for Huntington disease may be detrimental, using them in the cancer situation may not be cost-effective.  Further study is needed to establish the evidence.

4.      We cannot advise formally on any change of practice, until we have such evidence.   

 

References

[1] International Huntington Association, World Federation of Neurology Research Group on Huntington's Chorea.  Guidelines for the molecular genetics predictive test in Huntington's disease.  Neurol 1994;44:1533-1536.

2 Psychological model for presymptomatic test interviews: lessons learned from Huntington disease.  Soldan J, Street E, Gray J, Binedell J, Harper PS.  J Genet Counseling 2000;9(1):15-31.

3 Marteau TM, Croyle RT.  Psychological responses to genetic testing.  Br Med J 1998;316:693-696.

4 Brain K, Soldan J, Gray J, Sampson J.  Genetic counselling protocols for hereditary nonpolyposis colorectal cancer: a survey of UK centres.  Submitted for publication.