Galactosemia

Galactosemia (Orphanet code 352) is a group of inherited metabolic disorders characterized by the body's inability to properly metabolize galactose, a sugar found primarily in milk and dairy products. The most common and severe form is Classic Galactosemia (also known as Galactosemia type I or GALT deficiency), caused by deficiency of the enzyme galactose-1-phosphate uridylyltransferase. Other forms include Galactokinase deficiency (type II) and Galactose epimerase deficiency (type III). When galactose cannot be properly broken down, toxic metabolites accumulate in the blood and tissues, causing widespread damage to multiple organ systems including the liver, brain, kidneys, and eyes. In classic galactosemia, affected newborns typically appear normal at birth but develop life-threatening symptoms within the first days to weeks of life after ingesting breast milk or formula containing lactose. Key early symptoms include poor feeding, vomiting, diarrhea, jaundice, hepatomegaly (enlarged liver), liver failure, lethargy, and increased susceptibility to severe bacterial infections, particularly Escherichia coli sepsis. If untreated, the condition can rapidly progress to multi-organ failure and death. Cataracts may develop early and are a prominent feature in galactokinase deficiency. Classic galactosemia is now included in newborn screening programs in many countries, enabling early diagnosis. The cornerstone of treatment is immediate and lifelong dietary restriction of galactose, primarily through elimination of milk, dairy products, and other galactose-containing foods. Early dietary intervention can be life-saving and prevents acute complications. However, despite strict dietary compliance, many individuals with classic galactosemia develop long-term complications including speech and language difficulties, learning disabilities, cognitive impairment, motor abnormalities (such as tremor and ataxia), and premature ovarian insufficiency (POI) affecting the majority of females. These long-term complications are thought to result from endogenous galactose production and/or prenatal damage. Research into novel therapies, including pharmacological chaperones and gene therapy, is ongoing but no curative treatment is currently available.

Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.

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