Five years of screening for galactosaemia in South Africa: Pitfalls of using Benedict’s test and thin layer chromatography to screen for galactosaemia in a developing country

Abstract

BackgroundThe objective of the study was to investigate the effectiveness of screening for hereditary galactosaemia with Benedict’s test and thin layer chromatography (TLC) in a tertiary laboratory from a developing country. MethodsWe retrospectively analysed the results of tests done in suspected galactosaemia patients including Benedict’s test, thin layer chromatography, GALT activity and DNA analysis. Results878 paediatric patients were screened with Benedict’s test; the age range was 5 days to 19 years. 48% tested positive/trace on the Benedict’s test of which 52% of these had galactosuria evident on TLC. 22% of this sample had pathologically low GALT results on follow-up. 8 patients from the screened population were confirmed to have galactosaemia, in addition to 6 more patients diagnosed with galactosaemia without screening tests performed. Median ages at which the diagnoses were made in the screened and non-screened samples were 2 months and 6 months respectively. Confirmatory DNA testing was performed in 2 patients, whom were found to be heterozygous for S135L mutation. ConclusionInadequate performance of Benedict’s test and TLC was demonstrated by false positive and false negative results leading us to conclude that screening test results require interpretation with caution.