Newborn Screening in South Africa
Objective: to establish and expand Newborn Screening in South Africa, utilising RAI methodology for detection of Congenital Hypothyroidism and Tandem Mass Spectrometry for detection of the Phenylketonurias (PA), Tyrosinemias, Maple Syrup Urine Disease and other amino acid disorders, Urea Cycle disorders, Propionic Acidemia, (PA) Methyl Malonic Acidemia and other Cobalamine disorders, Isovaleric Acidemia, the Glutaric Acidemias (GA) and 14 Acyl Carnitines. Testing for Galactosemia was done in 11.7%, using a special kit.
Study Design: Dried blood spots taken by heel prick, written consent from mothers. The procedure explained by informative pamphlets in 6 of the official languages. Most infants are discharged within 24 hours after birth. Follow up of abnormal results was by telephone in the urban areas and by messages through the taxi network in the rural areas. Complete results are available in 48-72 hours and conveyed to the responsible hospital/paediatrician within another 24 hours. All data was stored at a centralised data base. Education of health professionals and the public about Newborn Screening was actively carried out throughout the whole time.
Results: 71,407 samples were received, of which 177 were repeat requests, 343 were duplicates and 663 were inadequate, leaving 70,224 unique first samples. 47.6% were male, 47.1% were female and in 5.3% sex not recorded. TSH testing: 70,119. Congenital Hypothyroidism was confirmed in 5 cases, 3 had midline cerebral defects, giving a diagnosis of secondary hypothyroidism. Expected incidence: 1:32,377 our figure 1:14,024
MSMS Testing: carried out in 24,006 samples. Positive cases:6:3 with PA, 2 with GA type 1 and 1 with PKU/Biopterin deficiency. Five other cases had abnormal results but were unresolved, and died or were lost to follow up. With the acquisition of a dedicated SMMS machine in 2004, 4 of 6 confirmed cases were found in the last 2 years of the study.
Galactose Testing was performed in 8210 (12.6%) and galactosemia was found in 2 cases. Expected incidence 1:47.0. Incidence in this series 1:4,105.
Conclusion: The incidence of IEM in this group of predominantly African infants was different than in previous reports in other African ethnic groups.