A newborn screening test is done in collaboration with North-West University and includes tests relevant to the South African population.
Newborn screening is a worldwide recognised public health measure aimed at the early screening, diagnosis and management of selected inherited diseases. Diseases are selected based on the current diagnostic and treatment capabilities and the demonstration of the positive economic impact of such interventions. Newborn screening is perhaps the pinnacle of preventative medicine. Early diagnosis and treatment ensure optimal living conditions and allows an individual to contribute to society as opposed to becoming a long-term societal responsibility.
There is a perception amongst many South African clinicians that inherited metabolic diseases are exceedingly rare in our country. However, the overall estimated incidence of inherited metabolic disease is 1:20001. The March of Dimes global report on birth defects found that genetic and congenital disorders affect all nations, regardless of ethnic background and socioeconomic status. Overall, there is little evidence to suggest that South Africa is immune to metabolic diseases.
For the past 30 years, the metabolic laboratory at North-West University’s Potchefstroom Campus has received over 50 000 requests for patient metabolic workups. The most common metabolic diseases that are also included in the newborn screening panel include isovaleric acidaemia, propionic acidaemia, galactosaemia, vitamin B responsive methylmalonic acidaemia, maple syrup urine disease and glutaric acidaemia type I. For many of the diseases in the newborn screening profile, simple and cost-effective treatments are available. The technology and know-how to perform newborn screening are available, and the logistical infrastructure already exists in many instances, albeit predominantly in the private sector. If there is greater support from the private sector, the public sector could be lobbied to offer newborn screening to all South African children.
Collection procedure
The ideal time for collection is between 1-3 days after the first feed, but up to a week after birth is still acceptable. The baby needs to have had a few feeds and started the digestion and metabolism of proteins, carbohydrates and fats to bring the disorder to light.
Tests performed outside of the ideal timeframe become less accurate. If a metabolic disease is suspected, then specific metabolic testing is required.
Blood is traditionally collected by a heel prick to the baby. Sometimes blood may need to be drawn from the baby’s vein instead of a heel prick. Five drops of blood are needed to be blotted on a Guthrie card.
The screening is then done with tandem mass spectrometry at the metabolomics unit at North-West University. This is the only lab in South Africa currently performing newborn screening.
References
Voster C. The case for Newborn Screening in South Africa: a personal perspective. Pathchat, Ampath, edition no.6.
Christianson A, Nowson C, Modell B. March of Dimes Global Report on Birth Defects. 2006. 2006 [cited 2013 Jan 22];