2. Genetic counselling and testing
Age 0-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-79 > 80
Genetic testing can be used for various purposes, from preconception planning (refer to Chapter 1. Preventive activities prior to pregnancy), during pregnancy, for neonates (newborn screening), during childhood and right through to adult-onset familial diseases (eg cancer, cardiac and neurodegenerative diseases).
In order to identify patients who may be at risk of a genetic disorder, a comprehensive family history must be taken from all patients, and this should be regularly updated. A family history should include first-degree and second-degree relatives on both sides of the family and ethnic background. Age of onset of disease and age of death should be recorded where available.
Increased frequency and early onset of cancers in families, premature ischaemic heart disease or sudden cardiac death, intellectual disability, multiple pregnancy losses, stillbirth or early death, and children with congenital abnormalities may suggest the presence of genetically determined disease. Patients of particular ethnic backgrounds may be at increased risk and may benefit from genetic testing for specific conditions. Possible consanguinity (eg cousins married to each other) should be explored, for example, by asking, ‘Is there any chance that a relative of yours might be related to someone in your partner’s family?’ General Practitioners (GPs) should consider referral to, or consultation with, a genetic service (general or cancer genetics) for testing because test results, which rely on sensitivity, specificity and positive predictive value, are not straightforward. Testing often involves complex ethical, social and legal issues. The time on waiting lists for genetic services is usually longer than one month, so direct consultation and liaison by telephone are necessary when the genetic advice could affect a current pregnancy. On the basis of current evidence, whole genome sequencing is not recommended in low-risk general practice populations (refer to Chapter 15. Screening tests of unproven benefit).
Clinical genetic services provide testing, diagnosis, management and counselling for a wide range of genetic conditions. Reasons for referral include:
- diagnosis of a genetic condition
- family history of a genetic condition
- recurrence risk counselling (eg risk of recurrence in a future pregnancy)
- pregnancy counselling (eg preconception, consanguinity)
- prenatal screening and testing
- presymptomatic and predictive testing for adult-onset disorders (eg cancer)
- discussions surrounding genetic testing
- arranging of genetic testing.
Services such as paternity testing or genetic testing/management of very common genetic conditions (eg haemochromatosis) are not provided by clinical genetic services.
Use of a simple family history screening questionnaire (FHSQ) can help identify individuals who may require a more detailed assessment of their family history of cancer, heart disease or diabetes (refer to Appendix 2A. Family history screening questionnaire for a published and validated FHSQ).1 This tool can be used as part of the patient assessment at their first visit to a practice. If a patient is uncertain about their family history, they can be asked to discuss the FHSQ with their relatives prior to completing the questionnaire. For patients with low literacy, the FHSQ may need to be completed with the support of a healthcare professional. A positive response to any question requires follow-up with a more detailed assessment of the family history. As family history can change, it is recommended that the FHSQ be repeated at least every years.
- Emery JD, Reid G, Prevost AT, Ravine D, Walter FM. Development and validation of a family history screening questionnaire in Australian primary care. Ann Fam Med 2014;12(3):241–49.
- Southern KW, Merelle MM, Dankert-Roelse JE, Nagelkerke AD. Newborn screening for cystic fibrosis. Cochrane Database Syst Rev 2009;1:CD001402.
- RANZCOG - College statements and guidelines [Accessed 19 April 2016].
- Ioannou L, McClaren BJ, Massie J, et al. Population-based carrier screening for cystic fibrosis: A systematic review of 23 years of research. Genet Med 2014;16(3):207–16.
- Delatycki M, Burke J, Christie L, et al. Population based carrier screening for cystic fibrosis. Position statement. Alexandria, New South Wales: Human Genetics Society of Australasia, 2013.
- The American College of Obstetricians and Gynecologists Committee on Genetics and The Society for Maternal-Fetal Medicine Publications Committee. Committee opinion no. 545: Noninvasive prenatal testing for fetal aneuploidy. Obstet Gynecol 2012;120(6):1532–34.
- Woolcock J, Grivell R. Noninvasive prenatal testing. Aust Fam Physician 2014 Jul;43(7):432–34.
- Bianchi DW, Parker RL, Wentworth J, et al. DNA sequencing versus standard prenatal aneuploidy screening. N Engl J Med 2014;370(9):799–808.
- Genetics in Family Medicine: Guidebook for General Practitioners [Accessed 15 April 2016].
- Facher J, Robin N. Genetic counselling in primary care. What questions are patients likely to ask, and how should they be answered. Postgrad Med 2000;107(3):59–66.
- Dick P. Periodic health examination, 1996 update. 1. Prenatal screening for and diagnosis of Down syndrome. Canadian Task Force on the Periodic Health Examination. CMAJ 1996;154(4):465–79.
- Cohen J, Lennox N. Fragile X syndrome. In: Lennox N, Diggens J, editors. Management guidelines: People with developmental and intellectual disabilities. Melbourne: Therapeutic Guidelines Limited, 1999.
- Mefford HC, Batshaw ML, Hoffman EP. Genomics, intellectual disability, and autism. N Engl J Med 2012;366(8):733–43.
- Murray A, Schoemaker MJ, Bennett CE, et al. Population-based estimates of the prevalence of FMR1 expansion mutations in women with early menopause and primary ovarian insufficiency. Genet Med 2014;16(1):19–24.
- Laml T, Preyer O, Umek W, Hengstschlager M. Genetic disorders in premature ovarian failure. Hum Reprod Update 2002;8(5):483–91.
- Premature and early menopause [Accessed 15 April 2016].
- Jacquemont S, Hagerman RJ, Leehey MA, Hall DA. Penetrance of the fragile X–associated tremor/ataxia syndrome in a premutation carrier population. JAMA 2004;291(4):460–69.
- Dormandy E, Bryan S, Gulliford MC, et al. Antenatal screening for haemoglobinopathies in primary care: A cohort study and cluster randomised trial to inform a simulation model. The Screening for Haemoglobinopathies in First Trimester (SHIFT) trial. Health Technol Assess 2010;14(20):1–160.
- Cunningham F, Bowden D. Suggested protocol for pre-conceptual and antenatal carrier testing for haemoglobinopathies. Clayton, Vic: Monash Medical Centre, 2013.
- Pagon RA, Bird TD, Dolan CR, Stephens K AM, editors. GeneReviews. Seattle: University of Washington, 2010.
- Sullivan D, Watts G, Hamilton-Craig I, and members of the Cardiovascular Genetic Diseases Writing Group. Guidelines for the diagnosis and management of familial hypercholesterolaemia. Sydney: Cardiac Society of Australia and New Zealand, 2013.
- Watts GF, Sullivan DR, Poplawski N, et al. Familial hypercholesterolaemia: A model of care for Australasia. Atheroscler Suppl 2011;12(2):221–63.
- Crawford D, Macdonald D. Haemochromatosis. 3rd edn. Mount Waverley, Vic: Digestive Health Foundation and the Gastroenterological Society of Australia, 2007.
- Powell LW, Dixon JL, Ramm GA, Purdie DM.
Screening for hemochromatosis in asymptomatic subjects with or without a family history. Arch Int Med 2006;166(3):294–303.
- Delatycki MB, Powell LW, Allen KJ. Hereditary hemochromatosis genetic testing of at-risk children: What is the appropriate age? Genet Test 2004;8(2):98–103.
- Whitlock EP, Garlitz BA, Harris EL, Beil TL, Smith PR. Screening for hereditary hemochromatosis: A systematic review for the US Preventive Services Task Force. Ann Intern Med 2006 Aug 1;145(3):209–23.
- EASL clinical practice guidelines for HFE hemochromatosis. J Hepatol 2010;53(1):3–22.
- Bacon BR, Adams PC, Kowdley KV, Powell LW, Tavill AS, American Association for the Study of Liver Diseases. Diagnosis and management of hemochromatosis: 2011 practice guideline by the American Association for the Study of Liver Diseases. Hepatology 2011;54(1):328–43.
- Goot K, Hazeldine S, Bentley P, Olynyk J, Crawford D. Elevated serum ferritin – What should GPs know? Aust Fam Physician 2012;41(12):945–49.