When a baby is aged between five to eight days old, a midwife pricks its heel with a special device and collects a few drops of blood on to an absorbent card. The card is then sent to a specialist laboratory and the dried blood spots are tested to screen for five rare inherited diseases. If these diseases are detected early in life, the baby can be treated, in order to improve health and prevent disability or even death. This programme has been running for 10 years and detects nearly 1,000 affected babies each year. Uptake is high, local figures showing that more than 99% of newborns are screened. Blood spots are currently tested for the following conditions:
- Sickle cell disease (SCD), a blood condition that needs to be treated to prevent serious illness. It affects about 350 of the 700,000 babies born in the UK each year
- Cystic fibrosis (CF) which affects the lungs and digestive organs and affects about 250 babies a year
- Congenital hypothyroidism (CHT) which causes severe mental and physical disability unless treated with replacement thyroid hormones (thyroid tablets). It is found in about 180 babies each year
- Phenylketonuria (PKU) which can cause severe mental disability if not treated by a restricted diet. It affects about 80 babies a year
- Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) which is a potentially life-threatening disorder of fat metabolism. Development can be normal with special care and attention to diet. There are about 70 cases a year.
The UK National Institute of Health Research has funded a trial that will add laboratory tests for a further five rare inherited diseases: maple syrup urine disease, homocystinuria and three types of acidaemia. All five conditions are treatable. The pilot scheme will screen some 430,000 newborns using the same blood spots that are tested in the current screening programme. It will start in July 2012 and the UK National Screening Committee will evaluate its results after one year.
Maple syrup urine disease results from failure to break down branched chain amino acids. It often starts in the newborn with a life-threatening acidosis. If not diagnosed and treated there is a life-long threat of brain damage. Homocystinuria is the result of impaired homocysteine metabolism. There are no early symptoms but, if not diagnosed by screening and treated, learning difficulties and eye sight problems due to lens dislocation develop in late infancy or early childhood. The three types of acidaemia, glutaric acidaemia type 1, isovaleric acidaemia and long chain fatty acidaemia, produce health problems that can range from mild to life-threatening, and commonly start with feeding difficulties. Between five and ten babies with each of these five conditions are born in the UK each year.
Professor Dame Sally Davies, Chief Medical Officer for England, said the new pilot study is a fantastic step forward. She added “The pilot will identify more babies with serious conditions, giving them the chance to live a long, healthy life”.