The Human Genome Project
The mapping of the human genome was completed in 2003. The significance of this to primary care will become clear over the next decade, as our understanding of the genome and clinical genetics increases. Genetic testing, including predictive testing, will undoubtedly increase over the next decade. Disease classifications will change, depending on disease genotype-phenotype characteristics. The challenge for primary care is to communicate these advances to our patients, to deal with the ethical dilemmas that will arise, and to meet our professional and educational needs by keeping our knowledge and skills up to date.
The ethos of the Human Genome Project has been to make the new knowledge and the advances in DNA technology freely available to the scientific community. The aim is to develop new avenues in the diagnosis, prevention and treatment of diseases ranging from single-gene disorders to more multifactorial conditions, such as diabetes and heart disease.
The spin-offs from the project have been the collaboration between scientists and physicians, the development of biomedical informatics (particularly large genetic, genomic and protein databases), and the advances in computational biology. There has also been increasing sociological and public health involvement in assessing the medical and societal consequences of the project,5and part of the budget for the project has been set aside specifically to assess the ethical, legal and social implications.
The information that the project has generated includes genetic maps, whereby sequenced gene markers can be used to isolate candidate genes. The importance of identifying genes and altered genes in terms of disease causation, particularly in common diseases, will depend on the presence of other modifier genes as well as environmental and behavioural factors. Thus the primary care practitioner in the future, when faced with the results of genetic tests, will need to have an understanding of the concept of genetic absolute or relative risk as well as the clinical validity and utility of a genetic test.6 New genetic disease classifications open up the possibility of genetic discrimination. The use of genetic testing that is relevant to employment and insurance will be of paramount interest to employers, insurance companies and pension funds, as well as government and legal services. The possibility of creating a genetic 'underclass' based on genetic differences, and ethnic and racial differences, needs to be considered when taking on board the new advances that are being made.
The prescribing of drugs is also likely to change over time, due to the emerging field of pharmacogenetics. Individualising of therapy based on inherited differences in drug metabolism will increase over time, and factors such as variations in the genes that are involved in drug metabolism, and new drug-receptor targets determined by molecular genetic research, will change the way in which practitioners treat diseases.
The challenge that needs to be met is the need to keep abreast of the impact of the advances that are being made in genetics. The media together with patient expectations will be two powerful drivers in the need to make primary care 'genetics literate.'
The primary care practitioner has responsibilities to the 'family' as well as to the individual patient, and challenges to the right of patient confidentiality are bound to occur when family members seek information about their own genetic risks.