There is a perception amongst many South African clinicians that inherited metabolic diseases are exceedingly rare in our country. These perceptions are based on a lack of recognition of these conditions when they present and also on misleading earlier research.¹ In more recent research, Van der Watt et al predicted an incidence of 1 in 5000 newborns for type I glutaric acidemia in a selected South African black population through estimation of the carrier frequency of a commonly occurring mutation.² Prof LJ Mienie has headed the Metabolic Laboratory on the Potchefstroom Campus of the North West University for the past 30 years and has received more than 50 000 requests for the metabolic workup of patients. In his experience the most frequently occurring metabolic diseases that are also included in the newborn screening panel are isovaleric acidemia, propionic acidemia, galactosaemia, vitamin B responsive methylmalonic acidemia, maple syrup urine disease and glutaric acidemia type I. The March of Dimes global report on birth defects found that genetic and congenital disorders cut across all nations with little regard for ethnic background and socioeconomic status. All in all there is little evidence to suggest that South Africa is spared from metabolic diseases.
One of the common constraints to the implementation of a newborn screening program is the perception such a program will come a huge expense and will divert funds from competing health priorities. The reality is that ample evidence exists to illustrate that the economic benefit of screening offsets the costs and that it is economically far better to screen and initiate early treatment than to diagnose late and deal with the associated morbidity and mortality.³˒⁴˒⁵˒⁶˒⁷
While most health care funders will agree that preventative health initiatives will lower the health care expenses of an individual over his or her lifetime, there seems to be less clarity on how preventative programs are prioritized. In South Africa, screening for HIV, hypercholesterolemia, breast cancer and prostate cancer is fairly common practise and is uncertain why these conditions were prioritized before newborn screening when at least some evidence indicates the opposite.⁷
A more realistic economic barrier is that the initial cost of screening is incurred straight away while the benefits are only realized over an extended period. In the light of this most developing countries have opted for an incremental approach to implementation through pilot programs. In addition a country must have reached a certain level of economic prosperity to make the implementation of a screening program feasible. Table 2 compares the economic prosperity (expressed as the GDP per Capita) and the percentage of annual newborns screened for selected developing nations.
There is an overwhelming case for newborn screening in South Africa. For many of the diseases in the newborn screening profile simple and cost-effective treatments are available and it seems completely unethical to deny the children of South Africa such interventions especially given the arguments that are put forward in this document. The technology and knowhow to perform newborn screening is available, while the logistical infrastructure already exists in many instances. The issue cannot be ignored any longer.