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Accredited education and learning

Click the link to complete an online education module on what healthcare professionals need to know about preconception and early pregnancy carrier screening for hereditary rare diseases. This learning module has been accredited by the RACGP as a QI&CPD CPD (Cat. 2) Activity (2 points) and is suitable for general practitioners, practice nurses, obstetricians, fertility specialists, general paediatricians and maternal child health nurses.

Patient resources

The following resources were developed by SMA Australia to help patients understand what testing involves and what it means if they are identified as a carrier of a rare hereditary disease.

  • Genetic Alliance logo
  • Genetic and Rare Disease Network logo
  • MacKenzie's Mission logo
  • Medical Research Future Fund logo

Click through to the above websites for further information and support for families and carers

Frequently asked questions

What is carrier screening?

Carrier screening is a form of genetic testing that can detect if an individual or couple are carriers of an autosomal recessive and/or X-linked genetic condition, when there is no a priori increased risk based on either partner’s personal or family history.1,9 Involving a simple mouth swab or blood test, it allows a woman or couple to understand their risk of passing an inherited condition on to their children.

What is the burden of inherited rare diseases?

Despite being individually rare, inherited rare diseases are collectively common. Approximately 1–2% of non-consanguineous couples have a one in four chance of having a child with a severe autosomal recessive or X-linked recessive genetic condition with each pregnancy.3 This means around one in 200 babies are born with an autosomal recessive or X-linked recessive condition, which represents approximately four times the frequency of pregnancies affected by Down syndrome (one in 800).4 Rare diseases are often complex and can cause severe disability, impaired quality of life and premature death.10 Around 20% of infant mortality and 10% of paediatric hospital admissions are associated with inherited disorders.5

Why offer carrier screening to patients?

Carrier screening enables women and couples who are planning a family, or in early pregnancy, to make informed reproductive choices in line with their personal wishes and values. Clinicians involved in family planning and antenatal care, such as general practitioners, fertility specialists, obstetricians and genetic health professionals, are ideally placed to have these conversations with patients.

What options are available for women and couples who are identified as carriers following screening?

Options available for 'carrier women' and ‘carrier couples’ following preconception screening include:2

  • proceeding to a pregnancy but accepting the possibility that they may give birth to an affected child – in which case, they may be better placed to optimise the child’s health and wellbeing (through early diagnosis and intervention)
  • undergoing fetal diagnostic testing (via amniocentesis or chorionic villus sampling) and terminating affected pregnancies or preparing for the possibility that they may give birth to an affected child
  • undergoing in vitro fertilisation (IVF) with preimplantation genetic testing (PGT) to screen embryos before they are implanted in the uterus
  • undergoing IVF with donor eggs, sperm or embryos
  • choosing to adopt or not have children.

Options available for 'carrier women' and ‘carrier couples’ identified during early pregnancy include:2

  • undergoing fetal diagnostic testing (via amniocentesis or chorionic villus sampling) and terminating affected pregnancies or preparing for the possibility that they may give birth to an affected child
  • proceeding without fetal diagnostic testing and preparing for the possibility that they may give birth to an affected child.

Carrier women = female carriers of an X-linked recessive condition
Carrier couples = couples in which both partners are carriers for the same autosomal recessive condition

Who should be offered carrier screening?

Traditionally, carrier testing was offered to adults with a family history of a recessive condition; to the partners and relatives of identified carriers; to the partners of people with the condition and/or to people of a particular ethnicity.9 However, this approach only identifies a minority of carriers, since the majority of affected children are born to parents with no previously known family history, and only a minority of relatives in high-risk families request carrier testing. Thus, it is now recommended that carrier screening be offered to all women planning a pregnancy or in the first trimester of pregnancy, regardless of family history or geographic origin.2

When should carrier screening be performed?

Ideally, carrier screening should be offered to women or couples who are planning a family as early as possible to allow them time to consider a wider range of reproductive options.3 As such, preconception carrier screening should be considered the ‘gold standard’ of care. When carrier status is determined before pregnancy, carriers should be referred for genetic counselling to review their options.2 Carriers then have the option of taking steps to avoid having an affected child if they so choose.

If a woman or couple presents for the first time in pregnancy, they should be offered carrier screening if they are still within the first trimester. Those found to have a higher risk of having an affected child following screening should then be referred for genetic counselling to understand their options.

Does carrier screening replace NIPT and combined first trimester testing?

Carrier screening does not replace non-invasive prenatal testing (NIPT) and combined first trimester screening (CFTS). These tests should still be offered to all pregnant women to screen for an increased risk of having a child with Down syndrome or other chromosomal disorder, as carrier screening does not detect chromosomal anomalies and NIPT and CFTS do not identify carrier status of single-gene disorders.1,8

Do both partners need to be screened?

Partners can be screened sequentially or simultaneously:2,3,11

  • Sequential screening involves testing one partner first – usually the woman, as carrier status is more relevant for X-linked conditions – and the male partner only if the female partner is found to be a carrier of an autosomal recessive condition. Sequential screening is generally more cost-efficient when screening for one or few conditions given that many couples will find they do not need to test the second partner. This method may be preferred where time is not limited (preconception screening).
  • Couple screening involves testing both partners simultaneously to determine a combined ‘low probability’ or ‘high probability’ result. A high probability is given when results identify both partners as carriers for the same autosomal recessive disorder or the woman is identified as a carrier for an X-linked disorder. Couple screening is the preferred test in early pregnancy, when time is of the essence due to laws around timing of termination (which differ by state and territory). It may also be preferred with expanded carrier screening due to the high chance of any individual being a carrier of one or more conditions.

What does carrier screening cost?

Medicare does not provide rebates for most genetic tests.* Patients can expect to pay fees in the range of:

  • single-condition screening: $100–$200
  • three-condition screening: $350–$400
  • expanded carrier screening: $580–$900.

*The cost of screening for haemoglobinopathies is generally covered by state/territory government funding. Relatives of affected individuals/carriers may be eligible to access funded testing via Medicare or state/territory government funding.
Fee estimates are per person. Actual fees vary by provider.

How can I order carrier testing?

Where can I refer a patient for genetic counselling?

A list of major genetic centres where patients can be referred for diagnosis and management of genetic conditions is available at: www.genetics.edu.au/genetic-services/general-genetics-clinics


References
  1. The Royal Australian College of General Practitioners. Genomics in general practice. East Melbourne, Vic: RACGP, 2019. Available at www.racgp.org.au/clinical-resources/clinical-guidelines/key-racgp-guidelines/view-all-racgp-guidelines/genomics-in-general-practice [Accessed 14 January 2020].
  2. The Royal Australian and New Zealand College of Obstetricians and Gynaecologists. Genetic carrier screening. East Melbourne, Vic: RANZCOG, 2019. Available at https://ranzcog.edu.au/RANZCOG_SITE/media/RANZCOG-MEDIA/Women%27s Health/Statement and guidelines/Clinical-Obstetrics/Genetic-carrier-screening(C-Obs-63)New-March-2019_1.pdf?ext=.pdf [Accessed 14 January 2020].
  3. Delatycki MB, Laing NG, Moore SJ, et al. Preconception and antenatal carrier screening for genetic conditions: The critical role of general practitioners. Aust J Gen Pract 2019;48(3):106–10. doi: 10.31128/AJGP-10-18-4725.
  4. Lalani SR. Current genetic testing tools in neonatal medicine. Pediatr neonatol 2017;58(2):111–21.
  5. Bell CJ, Dinwiddie DL, Miller NA, et al. Carrier testing for severe childhood recessive diseases by next-generation sequencing. Sci Transl Med 2011;3(65):65ra4. doi: 10.1126/scitranslmed.3001756.
  6. Archibald AD, Smith MJ, Burgess T, et al. Reproductive genetic carrier screening for cystic fibrosis, fragile X syndrome, and spinal muscular atrophy in Australia: Outcomes of 12,000 tests. Genet Med 2018;20(5):513–23.
  7. Delatycki MB, Alkuraya F, Archibald A, et al. International perspectives on the implementation of reproductive carrier screening. Prenat Diagn 2019:1–10. doi: 10.1002/pd.5611.
  8. The American College of Obstetricians and Gynecologists. Prenatal genetic diagnostic tests. Washington, DC: ACOG, 2019. Available at https://acog.org/Patients/FAQs/Prenatal-Genetic-Diagnostic-Tests [Accessed 17 January 2020].
  9. Henneman L, Borry P, Chokoshvili D, et al. Responsible implementation of expanded carrier screening. Eur J Hum Genet 2016;24(6):e1–e12. doi: 10.1038/ejhg.2015.271.
  10. Elliott E. Rare diseases are a ‘common’ problem for physicians. Aust Fam Physician 2015;44(9):630–33.
  11. De Costa CM, Douglas H. Abortion laws in Australia: It’s time for consistency and decriminalisation. Med J Aust 2015;203(9):349–50e1. doi: 10.5694/mja15.00543.

Acknowledgements

The RACGP gratefully acknowledges the contributions from the SMA and carrier screening expert advisory group in developing this education material:

  • Professor Jon Emery, GP, Herman Professor of Primary Care Cancer Research, University of Melbourne
  • Professor Martin Delatycki, Clinical Director, Victorian Clinical Genetics Services
  • Dr James Best, GP, Chair, Child and Young Person’s Health Network, RACGP
  • Associate Professor Michelle Farrar, paediatric neurologist, UNSW Sydney
  • Ms Julie Cini, CEO, SMA Australia
  • Professor Steve Robson, past president, the Royal Australian and New Zealand College of Obstetricians and Gynaecologists