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

background: The 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. methods: We retrospectively analysed the results of tests done in suspected galactosaemia patients including Benedict's test, thin layer chromatography, GALT activity and DNA analysis. results: 878 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. conclusions: Inadequate 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.