The entire genetic code of up to 100,000 newborn babies in England will be analysed by the NHS, with the aim of speeding up the diagnosis and treatment of more than 200 rare diseases.

At present, newborns are given a heelprick blood test that checks for nine serious conditions, including cystic fibrosis.

As part of this new study, led by Genomics England, blood samples will be taken from babies’ umbilical cords to help diagnose many more gene disorders, such as haemophilia and spinal muscular atrophy.

Hundreds of blood samples have already been collected from babies born at 13 hospitals in England; around 40 hospitals will eventually offer the test.

There are approximately 7,000 single gene disorders, but the programme will look only for those disorders that develop in early childhood for which there are effective treatments.

In some cases the diseases are curable, if caught early.

Screening newborn babies for these rare diseases involves sequencing their complete DNA – or genome – using blood samples from their umbilical cord.

At Birmingham Women’s Hospital, which is already offering the screening test, Dominika Nanus, 38, told me it was a “no-brainer” to take part in the study, having seen it advertised on a poster during an antenatal appointment.

She said her daughter Emilia, born the previous day, would “benefit directly but also contribute to wider research”.

Before she had even named her two-day-old son – now called Hugo – Jemma Jordan, 40, told me she had no hesitation in having him screened, because she would rather know if there were any health issues “from the offset”, and because it would help children in the future.

Dr Ellen Thomas, chief medical officer at Genomics England, said the 200 conditions the study looks for cause “substantial health problems early in childhood”.

“The treatments and interventions which are available for all of them can have a dramatic impact on that child,” she added.

At present it can take years for genetic diseases to be diagnosed, and these are often picked up only once a child becomes seriously ill.

Lucy White’s son Joshua, aged nine, has a rare genetic disorder called early juvenile Metachromatic Leukodystrophy (MLD), which is part of the new screening test.

Joshua was apparently healthy at birth, but his mobility began deteriorating at about the age of four, and in the past two years he has lost the ability to walk or talk.

Lucy, from Surrey, says it took more than two years of hospital appointments, specialist visits, scans and other procedures before they were given a diagnosis.

Had Joshua’s condition been identified at birth he might have been eligible for a clinical trial of a treatment now available on the NHS that can halt the damage done by MLD.

Lucy has given up work as Joshua needs round-the-clock care and is tube-fed. She says he may have only another 10 years to live as the genetic condition is progressive.

She urged parents to sign up for the screening test.

“Do not hesitate. If you can save your child’s life, that is more important than anything in this world,” she said.

When those children selected to take part in the study turn 16, they will be asked if they want to continue in the research programme, which could involve analysing other parts of their DNA for conditions that might potentially develop when they are adults.

This might include certain cancers, heart disease or dementia.

But it might also raise ethical questions about what health information is appropriate to share with individuals about their future health risks.

Genomics England said the entire focus of the study was on treatable conditions occurring early in childhood, and no decisions had yet been made on how whole genome sequences would be used in the future.

Dr Rich Scott, chief executive officer at Genomics England, called the study “a pivotal moment”.

He said the plan was to collect evidence to determine whether genomic newborn screening should be offered to all children.

NHS England chief executive Amanda Pritchard said diagnosing rare conditions in newborn babies through genomic testing “had the potential to give thousands of children the chance to access the right treatment at the right time, giving them the best possible start to life”.