Children in Wales critically ill with a suspected genetic illness are the first in the UK to be offered a test on the NHS to read their entire DNA code.
The test will deliver faster diagnoses of rare illnesses so doctors can decide on treatment more quickly.
Children previously needed a series of blood tests looking at specific genes as doctors attempt to find out what is causing their illnesses.
The new test will look at the entire genome in one go.
There are between 6,000 and 8,000 known genetic diseases, but many people with rare illnesses have to wait a long time for answers as experts try to pinpoint which genes might be responsible.
This can potentially mean years of uncertainty for them and their families, during which it might not be clear what the best treatment is.
Babies and children anywhere in Wales will be considered for the test, but only a limited number will be offered it.
Genetic tests have already helped two-year-old Dafydd, from Fishguard in Pembrokeshire, who fell ill shortly before his first birthday and was later diagnosed with a “one-in-a-million” condition affecting his limbs.
His mother, Louise Wilkinson, 39, said more and more tests were carried out on Dafydd but all doctors could do was rule out what he didn’t have. Then they had an idea to bring in the genetics team.
Broad-sweep genetic tests were carried out and within a couple of weeks the results returned; it found that both Louise and Dafydd’s father, Mark, were carriers of a rare faulty gene that they’d passed on to their son.
Dafydd was diagnosed with a Dopa-responsive dystonia, a neurological movement disorder.
His mother said that, within a few hours, doctors were able to start treatment and they were able to see improvements in him in a matter of days.
The tests solved “everything” and will make “all the difference” to families in the same situation, she said.
Since the system was first introduced in Wales in the spring, eight children have had their entire genome sequenced and the expectation is testing will be offered to about 20 young people per year, but it is hoped the eligibility criteria will be expanded to adults.
Dr Sian Corrin, rare diseases lead for the All Wales Genomics Service said: “Because there are so many genes that could be that cause, we don’t have the time to go through them one gene at a time.”
How does it work?
The test is a key element of a new service known as the Wales Infants and Children’s Genome Service (Wings).
It is currently offered to babies and children in intensive care units with suspected genetic illnesses with no clear cause.
Blood samples from these children are taken and processed in a state of the art genetic sequencer called the Illumina NovaSeq 6000.
The machine, which cost more than £1m, can read all 3.2 billion pairs of letters of a DNA sequence in multiple human samples in 48 hours.
After the entire DNA is read, experts look at potential changes in specific parts of the code which are known to cause symptoms similar to the illness of the child.
The doctors responsible for the child’s care then get that information.
Early results for the Wings service shows half of the babies and children tested to date have been found to have an underlying genetic condition and the results have changed their care.
The ambition to make Wales one of the leading countries in the world for genetic medicines was outlined in the Welsh Government’s Genomics for Precision Medicine Strategy published in 2017.
Wales’ Health Minister Vaughan Gething said: “I am incredibly proud that Wales is hosting the pioneering Wales Infants and Children’s Genome Service.
“Wings will play a major role in providing the right diagnosis, treatment or care pathway at the right time, helping shorten the diagnostic odyssey for children with undiagnosed genetic conditions, enabling clinicians, parents and carers make evidence informed decisions and reducing the anxiety of uncertainty.”
Moral and ethical considerations
The ability to look at a person’s entire DNA code raises important moral and ethical questions.
Experts say they will only look for information in a child’s DNA that they know will be relevant to their condition.
Families will also have a big say about what level information they would like to receive.
People with rare genetic conditions along with the families of children with rare illnesses have been part of the process of setting up the new system – giving advice as members of a sounding-board panel.