The NHS is promising a “genomic revolution,” with rare child diseases diagnosed in days, with far more accuracy than has previously possible.
Up to 700 babies and children a year will be offered a new form of DNA test, which can rapidly identify mutations in critically ill patients.
The Health Secretary said the new technology was “game changing” for the NHS, with experts saying the tests could double the chance of an accurate diagnosis and ensure swift treatment.
The technique, known as “whole exome sequencing” can reveal what is wrong with patients in days rather than weeks, reducing waits for worried families.
It means that within days, medics know which patients are unlikely to respond to particular treatments – preventing needless medication and potential side effects.
The NHS test looks for mutations in pieces of an individual's DNA that provide instructions for making proteins, usually taken from a blood sample.
The majority of disease-causing variants are thought to lie within these regions, collectively known as the exome.
Sir Simon Stevens, chief executive of NHS England said: “Once again the NHS is at the forefront of the genomic revolution with patients in England the first to be routinely offered this cutting edge treatment as part of the Long Term Plan.
“This quick and accurate new test means rapid diagnosis and reassurance for families when they need it most and give babies and children the best chance of a healthy and happy life.”
And he said the NHS would offer genomic testing to all cancer patients, and everyone suffering from rare disease within the next decade.
So far, 80 families have been offered the new £2,000 tests on the NHS, since rollout began in October.
Almost half were given a diagnosis within days - twice the rate achieved by standard tests, which take months.
Health and social care secretary Matt Hancock said: “I’m a passionate believer in the huge potential that technologies like genomics have to transform and improve people’s lives.
“The pain for families seeking a diagnosis for their sick children is unimaginable. These cutting edge DNA tests will much more rapidly diagnose rare diseases, helping to put an end to uncertainty and allowing children to receive the best possible treatment.
“This kind of genomic technology is game changing for the NHS, and will complement our existing commitment to offer whole genome sequencing to children with cancer and rare genetic disorders.
Mr Hancock recently said that in future, he wants to see all children offered whole genome sequencing at birth.
Henry Dunn had the test aged 20 months having experienced a range of undiagnosed problems and a prolonged spell in hospital after he was born.Within a week he was diagnosed with Costello syndrome - a rare disease that can affect multiple organ systems and leads to an increased risk of childhood cancer.He was closely monitored and on the two occasions he developed cancer it was detected early and successfully treated.Henry, now four, is in remission.
His mother, from Exeter, said: "Without the exome sequencing, Henry's diagnoses of rhabdomyosarcoma and liver cancer and treatment for these would likely have been delayed.
"Knowing that Henry has Costello syndrome provided the missing piece of the puzzle and means that he receives the medical management that he needs to make sure his needs are met and to help him achieve his full potential."