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Development of tests for disease using genetic markers is slower than expected

BMJ 2014; 349 doi: https://doi.org/10.1136/bmj.g7486 (Published 05 December 2014) Cite this as: BMJ 2014;349:g7486
  1. Nigel Hawkes
  1. 1London

Despite the promise of genomics and the frequent claims that it will revolutionise the practice of medicine, progress has been slower than anticipated, Stuart Hogarth, a research fellow at King’s College London, told a conference on 2 December.

His speech to the meeting, convened by the Progress Educational Trust, a charity that promotes ethically sound research and practice in genetics, assisted conception, embryo and stem cell research, and related areas, focused on biomarkers, generally deemed to be the “low hanging fruit” of the genomic revolution.

The hope had been that genomics would generate many new genetic biomarkers that would identify a person’s risk of a particular disease or could be used as reliable tests for the presence of the disease and the effects of treatment. But in fact the rate of discovery had been slow, and the reliability of many of the claimed links between genetic markers and diseases was questionable, Hogarth said.

“Patients and doctors need to be able to trust the diagnostic tests they are using,” he said. “They need to know they are reliable, and they need to know when it’s appropriate to use them and when it’s not, and they need to know what they’re going to do with that information. But at the moment we’re still very bad at conducting the translational research that answers those questions.”

Unlike the well established trials used in developing drugs, diagnostic tests have no clear development pathway. In the absence of that, there was a lack of appropriate rigour in the way tests were developed, he said. Too many were the result of “home brew” approaches in the laboratory, taken up by the industry but not properly regulated—at least in Europe. And the test kits that emerged at the end of the process were largely self certified by manufacturers, which decided that they had met the requirements of the regulations and put them on the market.

There were exceptions, such as the human papillomavirus (HPV) tests developed by Digene, a company that in the 1990s took part in many large trials designed to establish the tests’ value. Many other HPV tests have been developed, but of the 125 available worldwide Digene’s test is one of only four to have been approved by the US Food and Drug Administration. In Europe testing is much less rigorous, and of the 79 tests on the market only a small minority have been properly validated.

Hogarth estimated that 75% lacked proper validation: “not a happy situation.” Although more rigorous testing was being made mandatory in Europe, it would be several years before it became effective. While some companies were willing to do the necessary trials, in return they expected patent protection for their tests and a monopoly of the market, which could have the effect of increasing costs.

Earlier the conference had heard Julian Savulescu, professor of practical ethics at Oxford University, argue in favour of parents’ rights to select embryos for implantation that carried genes for desirable characteristics such as intelligence, beauty, or longevity, should such genes be identified. He put it more strongly, indeed, arguing that to select for such characteristics was a moral obligation because it enhanced children’s chances and added that UK legislation limiting preimplantation diagnosis was too restrictive.

“Choosing between embryos is not the same as saying some children are better than others,” he argued. “And the act of selection is not the same as saying that it affects the way you bring up a child.” Should deaf parents be allowed to select embryos to ensure that their children were also deaf, he was asked? “Legally, they should have the right to make that choice, though morally I think they would be making the wrong choice,” he said.

Ruth Deech, former chair of the Human Fertilisation and Embryology Authority, who was chairing the session, offered no judgment on the legal issue but observed that in practice it was unlikely to arise because few parents in the UK could at present access prenatal genetic diagnosis.

Notes

Cite this as: BMJ 2014;349:g7486

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