• Journal of The Korean Society of Inherited Metabolic disease
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• v.12 no.1
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• pp.58-63
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• 2012

Classical galactosemia (OMIM# 230400) is an autosomal recessive disorder of carbohydrate metabolism, due to a complete loss in galactose-1-phosphate uridyltransferase (GALT; E.C.2.7.7.12) enzyme activity. It caused by mutations in the GALT gene (OMIM$^*$ 606999) that is located at chromosome 9p13. The GALT enzyme deficiency results in a build-up of galactose and galactose-1-phosphate, causing life threatening complications such as feeding problems, failure to thrive, hepatocellular damage, bleeding and sepsis. However, Duarte galactosemia, a variant form of GALT deficiency, has residual GALT enzyme activities in erythrocytes and do not have manifest the symptoms of classical galactosemia. Since the advent of newborn screening (NBS) for galactosemia, we rarely encounter such overwhelmingly ill newborns. The positive NBS with no symptoms indicates the possibility of Duarte galactosemia besides a simple false positive and it has to be differentiated from classical galactosemia which is a medical emergency. In Korea, detection rate of Duarte galactosemia is very low and its genetic information is restrictive, too. We report a case of monozygotic twins with D/G galactosemia compound heterozygote in proven by the mutational analysis of GALT gene, which revealed N314D polymorphism and -119 to -116 delGTCA.