UP to 700 children a year across England will benefit from a new NHS DNA test capable of rapidly diagnosing rare diseases for critically-ill babies and infants.

So far 80 have received the ‘whole exome sequencing' technique with half being given a swift diagnosis.

The test doubles the chance of revealing what is wrong with patients in days rather than weeks.

Simon Stevens, chief executive of NHS England says: “Once again the NHS is at the forefront of the genomic revolution.

“This quick and accurate new test means rapid diagnosis and reassurance for families when they need it most and gives babies and children the best chance of a healthy and happy life. Over the next decade the NHS will continue to expand the range of personalised, precision medicines, including rolling out genomic testing to all people with rare diseases and cancer.”

Pioneered by scientists in Exeter, exome sequencing can identify a range of potentially life-threatening conditions all in one go.

Health 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."