For pregnant woman, known to be at risk of having a pregnancy affected by a genetic disorder, please make an urgent referral to Clinical Genetics via e-mail genetic.medicine@belfasttrust.hscni.net or contact the Clinical Genetics consultant or genetic counsellor on call (02895048022 or via Belfast Trust switchboard).
Clinical genetics may be involved in the care of couples who are at risk of having a pregnancy affected with a known genetic disorder in the family, or where differences have been detected during the pregnancy (e.g. on ultrasound) that suggest a possible underlying genetic diagnosis.
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Non-Invasive Prenatal Testing (NIPT) / Non-Invasive Prenatal Diagnosis (NIPD)
In very specific circumstances, it may be possible to undertaken genetic testing of the fetus using cell-free fetal DNA, which is circulating in the mother’s blood. Non-Invasive Prenatal Testing (NIPT) / Non-Invasive Prenatal Diagnosis (NIPD) is usually undertaken from ~9 weeks gestation.
If you are pregnant and have been informed in the past that you may be eligible for NIPT/NIPD based on a personal or family history, please get in contact with the Clinical Genetics department as early as possible to discuss your options. You can do this by e-mailing a self-referral form to genetic.medicine@belfasttrust.hscni.net.
Only some conditions will be suitable for NIPT/NIPD, and for some conditions NIPD may require several months of laboratory preparation.
For more information on the types of conditions which may be appropriate for NIPT/NIPD please see:
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Invasive prenatal testing (amniocentesis & chorionic villous sampling)
In some circumstances, genetic testing may be offered during pregnancy. This may be because the fetus is at risk of inheriting a known genetic condition in the family, or because differences have been detected during the pregnancy (e.g. on ultrasound) that suggest a possible underlying genetic diagnosis.
In order to obtain a sample of DNA from the fetus, invasive testing is usually required. Chorionic villous sampling (using a small needle to take a sample of tissue from the placenta) is usually undertaken between 11-14 weeks of pregnancy. Amniocentesis (using a small needle to take a sample of the fluid in the sac around baby) is usually undertaken between 15-20 weeks of pregnancy. Both of these procedures carry a small risk of miscarriage, estimated to be ~1%.
What type of genetic testing is undertaken on the fetus will depend on the family history and/or features detected on ultrasound (e.g. QF-PCR, microarray, gene panel test, trio exome sequencing). At the time of amniocentesis, a blood sample is usually taken from both biological parents.
For a summary of information on prenatal testing please see Prenatal testing information leaflet.
- For pregnant woman, known to be at risk of having a pregnancy affected by a genetic disorder, please make an urgent referral to Clinical Genetics via e-mail genetic.medicine@belfasttrust.hscni.net or contact the Clinical Genetics consultant or genetic counsellor on call (02895048022 or via Belfast Trust switchboard).
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Rapid exome sequencing during pregnancy
R21 Rapid exome during pregnancy local patient information leaflet
R21 Rapid exome during pregnancy Birmingham patient information leaflet
In very specific circumstances, rapid exome sequencing may be undertaken during pregnancy. The exome refers to the portion of the genetic material which codes for protein. The aim of sequencing is to look for spelling mistakes in the genetic code which can explains differences seen in the baby (i.e. to find a diagnosis).
To undertake exome sequencing we need a sample of DNA from the fetus (this involves invasive testing, such as amniocentesis and chorionic villous sampling). Exome sequencing during pregnancy is usually undertaken as a “trio”, where DNA from the fetus and both biological parents is analysed together. This requires a blood sample from both parents.
The National Genomic Test Directory provides some guidance on which patients may be suitable for R21 rapid exome sequencing during pregnancy. At present, this specialised service is provided by the West Midlands Regional Genetics Laboratory. Results from rapid prenatal sequencing usually take 3-4 weeks.
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Fetal pathology and post-mortems
In some circumstances, babies who have passed away before birth, or soon after, will undergo a post mortem examination at the Paediatric Pathology department in Alder Hey Hospital. These cases are discussed at a joint MDT meeting. In some cases, we will arrange to see families , to discuss the possibility of genetic testing. This may include karyotype, microarray and/or exome analysis.
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Preimplantation Genetic Diagnosis (PGD)
In very specific circumstances, couples may be eligible to apply for pre-implantation genetic diagnosis (PGD). PGD is a special type of in vitro fertilisation (IVF). Embryos are created outside of the body and are tested for a known genetic condition in the family. Only embryos which are not affected by the genetic condition are placed back into the womb.
Not all genetic conditions will be eligible for PGD. For further information on conditions which have been approved for PGD please see the HFEA website.
As this is a highly specialised service, funding must be approved as part of an extra contractual referral. The Clinical Genetics team can apply for this funding on your behalf, but funding is not guaranteed. There are also a number of exclusion criteria based on age, weight and smoking status, due to their impact on PGD success rates.
At present, PGD for our patients is provided by Guy’s Hospital, London. Couples have to travel to London for the initial appointments and treatments, however the majority of the maternity care, and the delivery, will be in Northern Ireland. There is a waiting list to be seen (typically months). If funding is agreed, financial support for travel and accommodation can be provided.
Further information and FAQs can be found on the Guy’s Hospital website: Pre-implantation genetic testing (PGT-M/SR) – Overview | Guy’s and St Thomas’ NHS Foundation Trust (guysandstthomas.nhs.uk)
For a summary of information on prenatal testing and PGD download the Prenatal testing information leaflet.
Antenatal Results and Choices (ARC) are a national charity “helping parents and healthcare professionals through antenatal screening and its consequences”. They aim to offer “impartial information and support to expectant parents facing decisions about antenatal tests and results” and to “provide independent, accurate, unbiased information so that parents can take the decisions that are right for them”. They also aim to provide emotional support and signposting to other relevant organisations.
Further information on their remit and contact information can be found on the ARC website.