What is the Genetic Testing of Embryos?
What is genetic testing of embryos (PGT-A / PGT-M / PGT-SR / PGT-P)?
PGT-A (Aneuploidy testing) - This screens embryos for the right number of chromosomes. Humans normally have 46 chromosomes in 23 pairs; an embryo with an extra or missing chromosome is called aneuploid.
PGT-M (Monogenic disorders) - This tests embryos for a specific single-gene disorder that the parents are known to carry. Examples include cystic fibrosis, Huntington's disease, sickle cell disease, Tay-Sachs, BRCA1/2 mutations, fragile X syndrome, and muscular dystrophy.
PGT-SR (Structural rearrangements) - This tests embryos when a parent carries a chromosomal rearrangement like a balanced translocation, where chromosome pieces are swapped but no genetic material is missing.
PGT-P (Polygenic risk) - This test uses polygenic risk scores to estimate an embryo's relative risk for complex conditions influenced by many genes: heart disease, type 2 diabetes, certain cancers, schizophrenia, and (more controversially) traits like height or educational attainment.
What is LCRH’s view on PGT-A?
LCRH often advocates PGT-A testing in certain patients to:
Reduce the miscarriage rate and the risk of aneuploid pregnancy and birth.
Reduce the number of unsuccessful embryo transfers therefore reducing the time taken and expense incurred to achieve pregnancy.
Reduce the storage and storage cost of non-viable embryos
Provide answers in the wider fertility investigation
LCRH works closely with Juno Genetics and Professor Dagan Wells
https://www.lcrh.co.uk/pgta-testing
https://www.lcrh.co.uk/lcrh-price-list
What is LCRH’s view on PGT-M?
We recommend PGT-M testing when one or both parents are known carriers of these specific single-gene disorders (often identified through family history or carrier screening), there's a previous affected child, or there's a strong family history of a heritable condition. Our partner laboratories will design a test customised to the specific mutation in that family, which takes some setup time before the IVF cycle.
PGT-M is well-established and broadly accepted as appropriate when there's a serious heritable condition in the family. It allows couples who would otherwise face a 25–50% risk per pregnancy of an affected child to transfer only unaffected embryos.
https://www.lcrh.co.uk/lcrh-price-list
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What is LCRH’s view on PGT-SR?
We recommend PGT-SR testing when a parent carries a chromosomal rearrangement like a balanced translocation, where chromosome pieces are swapped but no genetic material is missing.
PGT-SR identifies embryos with a balanced chromosomal arrangement before transfer.
https://www.lcrh.co.uk/lcrh-price-list
What is LCRH’s view on PGT-P?
LCRH has been strong advocate for selective PGT-A testing and for patient choice for many years but does NOT feel there is currently sufficient evidence for efficacy of PGT-P.
Using polygenic risk scores — statistical models that aggregate the small effects of thousands of common genetic variants — to estimate an embryo's relative risk for complex conditions influenced by many genes currently explain only a modest fraction of the variance in most traits.
PGT-P is offered commercially by a handful of US companies, but most professional bodies — including the European Society of Human Reproduction and Embryology, the HFEA and the American Society for Reproductive Medicine — currently advise against PGT-P for routine clinical use, and it's not offered by the NHS or licensed for use in the UK.
