Sickle cell blood test cuts miscarriage risk

A SIMPLE blood test could soon diagnose sickle cell disease in unborn babies.

Until now, the debilitating inherited condition – which causes those with it to produce unusually shaped red blood cells – could only be picked up during pregnancy during an invasive procedure known as amniocentesis.

This test is routinely offered to mothers-to-be who are at high risk of having a baby with Down’s syndrome, and also other genetic diseases, including sick cell.

It involves inserting a needle into the mother’s abdomen, and removing and testing a small sample of cells from amniotic fluid – the liquid which surrounds the growing baby in the womb.

However, this carries an up to one in 100 chance of triggering a miscarriage – so many parents opt not to have it. The new sickle cell blood test, which checks for fragments of foetal DNA circulating in the mother’s blood, could spare thousands of pregnant women from this risk.

Around 14,000 people in the UK are living with sickle cell. It is more common among people with an African or Caribbean background and can cause tiredness and shortness of breath, because the abnormally shaped blood cells cannot carry sufficient oxygen around the body. Babies born with the disease are also at an increased risk of infection.

The new test could be carried out at eight weeks gestation, instead of 16, as is the case with amniocentesis.

‘This could give women more safety, more options and more autonomy in their care,’ says Professor Eugene Oteng-Ntim, consultant obstetrician at Guy’s and St Thomas’ Hospital in London.

‘Because the current test carries a risk of miscarriage, many women opt not to have it, and miss out on having this crucial information about their baby that can help us to plan their care.’

A study, published in the British Journal of Haematology, involved 64 pregnant women, all of whom had the blood test. The test provided conclusive results for 60 of them and was found to accurately predict whether the babies of these mothers would be born with sickle cell disease. Babies develop the condition if they have inherited two faulty sickle genes – one from their father and one from their mother.

The test needs to be trialled in larger groups but Prof OtengNtim hopes it could be available more widely in just a few years.

Similar non-invasive tests are already available to screen for conditions such as Down’s Syndrome, and are already offered on the NHS in some areas.

‘We have been trying to do this for years,’ Prof Oteng-Ntim says. ‘This may be a game-changer.’