The patient population
Diseases with a genetic component are estimated to affect at least 5–6% of the population. Approximately 5–10% patients with cancer have hereditary cancer and prevalence of some cardiac conditions with a genetic basis is high, eg familial hypercholesterolaemia (1 in 250 population), and cardiomyopathy (1 in 500).
Genetic disorders are often rare (defined as affecting fewer than 5 in 10,000 of the general population). More than 5,000 rare diseases have been identified, and around 80% of rare diseases are genetic. One in 17 of the population has a rare disease, with a higher prevalence in populations where parental consanguinity is more common. These diseases can be hard to diagnose and patients can face long delays in diagnosis. Genetic disorders may affect several generations of the same family, and include relatives who are at risk and in need of clinical genetics services.
Prevention of disease
Fundamental to the practice of clinical genetics is the prevention of disease through targeted interventions. Pre-symptomatic or predictive genetic testing for a wide range of conditions including cancer, cardiac and some neurological conditions enable targeted therapies and screening for the individual and wider family, following cascade testing. A significant benefit to individuals and to the NHS is that patients found to be not at risk can be reassured and discharged from unnecessary screening programmes.
For patients with rare diseases, early diagnosis allows surveillance and prevention of complications. Early diagnosis allows for clarification of reproductive risks for couples before the birth of a further affected child. Early recognition of a possible genetic disorder is important given the lengthy process of evaluation, genetic testing and interpretation (see Department of Health, Our inheritance, our future: realising the potential of genetics in the NHS, 2003).
Clinical genetics supports the national population screening programmes, including prenatal screening for sickle cell and thalassaemia (SCT), fetal anomaly screening (FASP), newborn blood spot screening (NBS) and adult cancer screening.
Planning effective services
Detailed service specification is outlined in the NHS standard contract for medical genetics (all ages) (opens PDF, 380.86KB). The medical genetics clinical reference group oversees the service specification for clinical and laboratory services, taking advice from the rare disease advisory group at the Department of Health and the specialist societies. See Rare Disease UK’s report from 2013, Improving lives, optimising resources: a vision for the UK Rare Disease Strategy (opens PDF) and the Department of Health/Human Genome Strategy Group’s report Building on our inheritance (opens PDF, 824.2KB).
Currently, inequity of access to genetic services exists across the UK because of different commissioning models with some services funded through block contracts and others by tariff.
The current recommendations for services are two full-time equivalent consultants and four full-time equivalent genetic counsellors per million population for general genetic services. Additional personnel are required to deliver specialist services such as cancer or cardiac genetics. Services vary widely in the overall number and skill mix.
Future service development needs
Clinical genetics services need to develop new ways of working to cope with the demands posed by the large number of results from new genomic technologies. The traditional model of care will be altered as patients present to clinical genetics services with results from genetic testing already undertaken. There is a pressing need for the development of common standards for triaging of referrals across all UK services to ensure equity.
Interfacing with mainstream specialties and primary care could be improved through better use of IT and web-based resources.
Other models of service delivery by telephone or e-consulting will become more appropriate but these will require not only development of IT capacity but also a change in commissioning because the current tariffs encourage face-to-face consultations only.