Predictive or not predictive: understanding the mixed messages from the patient's DNA sequence.

AIMS AND OBJECTIVES: The aim of this discussion paper is to enable nurses to understand how deoxyribonucleic acid analysis can be predictive for some diseases and not predictive for others. This will facilitate nurses to interpret genomic test results and explain them to patients.

BACKGROUND: Advances in technology mean that genetic testing is now commonly performed by sequencing the majority of an individual's genome or exome. This results in a huge amount of data, some of which can be used to predict or diagnose disease.

DESIGN: This is a discussion paper.

METHODS: This paper emerged from multiple discussions between the three authors over many months, culminating in a writing workshop to prepare this text.

RESULTS: The results of DNA analysis can be used to diagnose or predict rare diseases that are caused by a mutation in a single gene. However, while there are a number of genetic factors that contribute to common diseases, the ability to predict whether an individual will develop that condition is limited by the overall heritability of the condition. Environmental factors (such as lifestyle) are likely to be more useful in predicting common disease than genomic testing. Genomic tests may be of use to inform management of diseases in specific situations.

CONCLUSIONS: Genomic testing will be of use in diagnosing disorders due to single gene mutations, but the use of genomic testing to predict the chance of a patient being affected in the future by a common disease is unlikely to be a realistic option within a health service setting.

RELEVANCE TO CLINICAL PRACTICE: Nurses will increasingly be involved in the use of genomic tests in mainstream patient care. However, they need to understand and be able to explain to patients the practical applications of and limitations of such tests.