What did the project achieve?
A new blood test can be used to reliably diagnose cystic fibrosis. The test developed by Professor Lyn Chitty and her team at UCL Great Ormond Street Institute of Child Health is safer and can be offered much earlier on in pregnancy than the traditional method. It is already helping couples who wish to find out if their baby has inherited this serious condition.
Cystic fibrosis (CF) and spinal muscular atrophy (SMA) are two of the most common genetic conditions in the UK. If both parents carry a copy of the faulty gene, their children will each have a one in four chance of inheriting the condition.
Couples who both carry the CF gene already have the option of undergoing an invasive test from 11 weeks of pregnancy, but this comes with a small risk of miscarriage. The new test has several advantages – it is non-invasive as it only requires a sample of the mother’s blood, can be carried out from four weeks of pregnancy and eliminates the risk of miscarriage.
The team’s new diagnostic test for CF involves analysing tiny amounts of the baby’s DNA that are released into the mother’s bloodstream using a sophisticated technology called next-generation sequencing.
After thorough testing, the team showed that the new method can accurately determine if the baby has inherited a faulty CF gene from both their mother and father. After gaining regulatory approval, the test is being offered to couples who are at risk of having a baby with this condition. The uptake from parents is high, much higher than for invasive testing – the definitive non-invasive prenatal diagnosis has been offered to more than 60 families.
The team has also developed a similar test for SMA, and plan to make this available to eligible families, like the CF test, via the new NHS Genomic Medicine Service Test Directory. Access to earlier, safer testing will help ensure more parents get more time to seek out expert advice and plan for the future.
This research was completed on
Professor Lyn Chitty’s team at Great Ormond Street Hospital and the UCL Institute of Child Health is developing safer ways to diagnose two genetic conditions in babies during pregnancy: cystic fibrosis, which affects over 10,000 people in the UK, and spinal muscular atrophy (SMA), which affects 2,000 to 2,500.1-3 Existing tests can’t be done until at least 11 weeks into pregnancy and, because they’re invasive, they slightly increase women’s chances of losing their babies through miscarriage. The new tests, which just need a blood sample from the mother, should be suitable for use earlier in pregnancy and should eliminate the risk of miscarriage.
This is a joint project which is being funded by Action Medical Research, Great Ormond Street Hospital Children's Charity and the Cystic Fibrosis Trust.
How are children’s lives affected now?
Cystic fibrosis (CF) is a progressive disorder, mostly affecting the digestive tract and lungs, which become clogged with thick, sticky mucus, leading to tissue damage. Babies with cystic fibrosis have changes – or mutations – in a particular gene. They have two copies of the altered gene – one inherited from their mother and one from their father. Parents who both carry the altered gene have a one in four chance of having a baby with the condition.
SMA is an inherited muscle-wasting condition that can affect a person’s ability to crawl and walk, to move their arms, hands, head and neck, as well as their breathing and swallowing. As with cystic fibrosis, children with SMA have two copies of an altered gene and parents who are carriers of this gene have a one in four chance of having another baby with SMA.
Tests can reveal whether an unborn baby has cystic fibrosis or SMA. However, at the moment they can’t be done until at least 11 weeks into pregnancy and they’re invasive – they involve inserting a needle through the tummy into the womb – so there’s a small risk of miscarriage.
How could this research help?
Professor Chitty’s team is developing new diagnostic tests, which analyse genetic material – DNA – in a sample of a mother’s blood to find out whether her unborn baby has the genetic changes seen in cystic fibrosis or SMA. Fragments of a baby’s DNA circulate in the mother’s bloodstream during pregnancy.
As the new tests only require a sample of blood from the mother, they avoid the need for an invasive test and so are safer. They can also be done earlier, from around 9 weeks of pregnancy. By enabling an earlier diagnosis, the tests should also give parents more time to seek out expert advice and plan for the future.
1. Cystic Fibrosis Trust. About cystic fibrosis. http://www.cysticfibrosis.org.uk/about-cf Website accessed 13 October 2015.
2. UK Cystic Fibrosis Registry. Cystic fibrosis: strength in numbers. Annual data report 2014. https://www.cysticfibrosis.org.uk/~/media/documents/the-work-we-do/uk-cf-registry/2014-registry-annual-data-report.ashx?la=en Website accessed 13 October 2015.
3. Spinal Muscular Atrophy Support UK. Key facts about spinal muscular atrophy. http://www.smasupportuk.org.uk/key-facts-about-sma Website accessed 13 October 2015.
|Professor Lyn S Chitty BSc, PhD, MB BS, MRCOG
|Dr Suzanne C Drury PhD BScDr Vincent Plagnol PhD
|Genetics and Genomic Medicine, UCL Institute of Child Health, NE Thames Regional Genetics Laboratory, Great Ormond Street Hospital, London
|Project Location Other
|UCL Genetics Institute, University College London
|20 July 2015
|Project start date
|1 May 2016
|Project end date
|31 December 2018