Course : MOC Part IV: Classic Galactosemia
Classic Galactosemia is an autosomal recessive disorder caused by impairment in the enzyme Galactose-1-Phosphate uridyltransferase (GALT). This creates an accumulation of galactose-1-phosphate, which has a toxic effect on the liver producing prolonged neonatal jaundice of the newborn. Enzyme activity is diagnostic and DNA analysis can be helpful. There are to some extent genotype-phenotype correlations with respect to enzyme activity and outcomes, however this has currently little or no impact on management. In the differential diagnosis are variant forms of transferase deficiency, and deficiencie s o f UDPgalactos e epimeras e (GALE ) can lead to elevated galactose-1-phosphate levels but normal GALT activity. A screen positive newborn for GALT deficiency requires immediate change of lactose containing milk to soy-based formula while evaluation for Classic Galactosemia continues. Chronic outcome of treated newborns may include cataracts, dyspraxic speech, growth restriction, ataxia, and premature ovarian insufficiency. All patients require quality medical services from a metabolic specialist, including clinical evaluation, diagnostic confirmation by laboratory testing to include pre-feed, RBC galactose-1-phosphate and GALT activity preventive management of disease-specific manifestations, treatment and genetic counseling. Carrier testing in classic galactosemia is possible with enzyme assay but may be improved with DNA testing for identified mutations and prenatal diagnosis is possible only with DNA analysis, so all families should be offered DNA testing.
ACMG Members and ACMG Trainees ($25)
Provide initial and ongoing care to patients diagnosed with galactosemia. This does NOT include the follow up of newborn screen abnormalities but focuses on patients diagnosed with galactosemia.