SUPERStudy: Galactosemia
Introduction: Galactosemia is a rare inherited metabolic disorder that affects the body’s ability to process galactose, a type of sugar found in milk.If left untreated, it can lead to serious health problems, including liver damage, brain damage, and even death.
Etiology: Galactosemia is caused by a deficiency of an enzyme called galactose-1-phosphate uridyl transferase (GALT). This enzyme is necessary to break down galactose into glucose, which the body can use for energy. Without this enzyme, galactose and its toxic byproducts build up in the blood and tissues.
Epidemiology: Hereditary galactosemia is among the most common carbohydrate metabolism disorders. 1 case per 40,000-60,000 persons.
Inheritance: autosomal recessive
Pathogenesis: The biochemical abnormality consists of a defect in galactose-1-phosphate uridyltransferase as a result of a mutation in GALT. This enzyme catalyzes the conversion of galactose-1-phosphate to uridine diphosphate galactose.
Clinical Manifestations:
Infants: the onset of symptoms is in the first days of life, after the ingestion of milk; vomiting, diarrhea, drowsiness, inattention, hypotonia, failure to thrive, bulging fontanels, liver and spleen enlargement, jaundice, anemia, hepatic cirrhosis, renal Fanconi syndrome, thrombocytopenia, cataracts, intellectual disability, seizures, and sepsis.
Older children and adults: Fatigue, speech difficulties, learning disabilities, ovarian failure in females, early onset cataracts.
Diagnosis:
Galactosemia is typically diagnosed through newborn screening tests for three forms of the enzyme. Galactose-1-phosphate is elevated in red blood cells. When the diagnosis is suspected, galactose-1-phosphate uridyltransferase should be assayed in erythrocytes or GALT sequencing pursued.
Treatment: The primary treatment for galactosemia is a lifelong lactose-free diet; if this is instituted early, the brain should be protected from injury.
SUPERPoint: If galactosemia is not treated, death frequently occurs within 1 month, often from Escherichia coli sepsis.
SUPERFormula: Infant with vomiting, diarrhea in the first days of life after the ingestion of milk + failure to thrive + bulging fontanels, liver and spleen enlargement, jaundice, anemia, hepatic cirrhosis, cataracts, renal Fanconi syndrome, sepsis + a defect in galactose-1-phosphate uridyltransferase = Galactosemia