FORTY per cent of the babies born in Britain in the week starting on March 3rd 1946 became the first subjects in a project that eventually achieved global scientific renown (and inspired its share of laboratory envy). Along with children from three younger generations, 58,000 in total, those babies have been followed by researchers throughout their lives. Troves of data on everything from child development to ageing have helped to shape health care in Britain and beyond.

Now the National Health Service is launching another big-data programme that could be just as transformative. From October, NHS England will begin to routinely carry out a standard set of genomic tests for some cancers and rare diseases, filling in the patchy use of such tests today. Crucially, for patients who consent, the data from these tests will be held at a national research centre along with their health records. The NHS’s size, universal coverage and cradle-to-grave health records promise to make the database uniquely useful.

Genomics is a powerful technique. About 7% of people in Britain will at some point have a rare disease (one that affects fewer than one in 2,000 people). Such diseases are usually caused by a single genetic mutation and first strike in childhood. Patients go through what doctors call the “diagnostic odyssey”, which typically takes three to five years and involves batteries of tests. Genomics sets out to shorten the journey, by comparing their genomes with those of their parents. This can help doctors spot the disease’s cause and whether it is hereditary in a matter of weeks. In some rare diseases, such early diagnosis can be life-saving. Familial hypercholesterolaemia, for example, causes dangerously high cholesterol which, if untreated, can cause heart attacks at an early age.

Most rare diseases, however, have no treatment—and this is where the NHS data will be particularly fruitful. Because NHS England covers 55m people, researchers should be able to find several patients with a rare disease, compare its progress in them, and identify any lifestyle, diet or other factor that affects the prognosis.

In cancer, another disease caused by genetic changes, researchers may be able to use the new centre to identify a key mutation and then go on to match the cancer to medicines that can treat it. Data gathered by the testing services can help show which treatment works best with which particular genetic profile.

The giant data centre where all NHS genomic records will be stored is already up and running, with patient files from a project that has been a pilot study for the new service. Its collection of 82,000 genomes from patients with cancers and rare diseases is already mined by nearly 3,000 researchers from more than 20 countries.

As new research becomes available, the NHS’s genomic-test menu will change, says Mark Caulfield from Genomics England, which runs the pilot study. Tests for gene variations that may cause adverse reactions to some drugs are one research priority. Some diagnoses that now require sequencing of the entire genome (which takes a powerful computer a day and costs about $1,000) will be accomplished with a single-gene test (which takes minutes using a machine the size of a shoebox).

Ever-cheaper sequencing will also help. Testing for combinations of gene variants that predispose people to expensive chronic ailments, such as diabetes, say, can help target prevention. By some estimates, 40-70% of drug prescriptions may be useless. As with cancer, the NHS can save money by detecting which combinations of genes and drugs are effective and which not. America and France are to copy bits of the new system. In the world of research, that is the sincerest form of flattery.