Newborn screening for classic galactosemia and primary congenital hypothyroidism in the Nkangala district of the Mpumalanga province of South Africa.

Abstract

Objectives: The main objective of this work was to establish the newborn incidence of classic galactosemia and congenital hypothyroidism within the Nkangala district of Mpumalanga. In the process a cost effective protocol for newborn screening of both diseases was developed.
Study design and setting: Blood spot specimens were collected from over 30 % of newborn infants in the Nkangala district of Mpumalanga Province in a six month period from June to November 2005. The specimens were subsequently screened for classic galactosemia and hypothyroidism using metabolite quantification assays. GALT (galactose-1-phosphate uridyltransferase) enzyme activity assays were also performed to confirm the reliability of the total galactose assays. Real-time PCR was used to detect commonly occurring mutations in the GALT gene that cause galactosemia.
Subjects and outcome measures: Informed consent was obtained from the parents of the newborn infants prior to commencement of screening. Total galactose levels of above 0,9 mg/L and TSH concentrations of above 25,1 mU/L were considered to be indicative of galactosemia and hypothyroidism, respectively. A decrease in the total financial input on the screening protocol was evaluated for significance in cost reduction.
Results: The incidence of hypothyroidism was found to be 0.1 % while none of the newborns presented with classic galactosemia. There was up to 20 % reduction in direct input costs of screening when our protocol is applied.
Conclusion: Cost effective newborn screening is possible when classic galactosemia and congenital hypothyroidism are screened, simultaneously. Cumulative disease frequency plots confirm the already established fact that hypothyroidism tends to prevail in higher frequencies than classic galactosemia