A girl in Madagascar suffering from sick-cell anaemia

    Horrible diseases are being ‘edited out’ of the human body

    18 May 2015

    Some exciting news about the future of medicine was announced today. Unfortunately, you really need a degree in biochemistry – which I certainly don’t have – to understand it. But we’d better get used to that, because the eradication of nasty diseases is increasingly a project for geneticists whose findings are difficult to grasp (but easy to misunderstand).

    Editas, described as a ‘leading genome editing company’, has announced the highlights of the 18th annual meeting of the American Society of Gene & Cell Therapy (ASGCT) in New Orleans. Here’s just one of them:

    Gene conversion of the hemoglobin locus: Several CRISPR/Cas9 construct variants were evaluated in vitro to target the human hemoglobin beta gene (HBB) in the region mutated in sickle cell anaemia. The construct containing the Streptococcus pyogenes D10A nickase isoform with selected gRNAs drove in vitro editing to approximately 30 percent of the HBB locus through gene conversion by the hemoglobin delta (HBD) locus. This suggests a potential therapeutic approach to treat sickle cell anaemia in which correction of the sickle-cell mutation may be achievable through CRISPR/Cas9-mediated gene conversion.

    I’d be bluffing if I said I knew exactly what that meant. But I have heard of sickle-cell anaemia, which killed 176,000 people, mostly in sub-Saharan Africa, in 2013, up from 113,000 deaths in 1990.

    The NHS describes sickle-cell anaemia as ‘a serious inherited blood disorder where the red blood cells, which carry oxygen around the body, develop abnormally’.

    There’s no single way of dying from the disease: people who inherit it are vulnerable to stroke, dangerously high blood pressure, all sorts of infections and sudden failure of the lungs. There’s currently no cure – but that dense paragraph from ASGCT holds out the hope of one.

    Gene therapy may soon be able to correct the mutation that, effectively, pollutes the blood of sickle-cell anaemia sufferers. This would involve the sort of genetic screening for heart disease and diabetes that I blogged about earlier.

    The New Orleans conference also raised the prospect of genetic therapy for Leber congenital amaurosis, a rare retinal disease that causes severe vision loss. It has nothing in common with sickle-cell anaemia – except its origins in a mutation that could one day be corrected.

    It’s not news that genetic manipulation is the only way to treat many genetic diseases. But the specific advances just announced are news – in the case of sickle cell anaemia, possibly life-saving for hundreds of thousands of people.

    Editas uses striking language to describe the grand project of gene therapy:

    Genome editing enables sequence-targeted modifications of DNA. Recent advances in this field have made it possible to modify almost any gene in the human body with the ability to directly turn on, turn off or edit disease-causing genes. This has the potential to address diseases that have previously been intractable to traditional gene therapy, gene knock-down or other genome modification techniques.

    We shall see. Turning microscopic research into affordable drugs is a complex and ruinously expensive business, and should make us think twice before assuming that Big Pharma is always up to no good. This is evidence-based medicine at its most refined and specialist. It requires massive funding if it is to achieve its aim of ‘editing out’ vile diseases from the human body.

    All of which makes it incomprehensible that, as Prof David Colquhoun noted last week, UK government money is still being spent on the witchcraft of homeopathy.