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Title
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Galactokinase deficiency
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ImagePath
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System
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carbohydrate metabolism disorder
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Overview
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Autosomal recessive error of galactose metabolism due to absent or severely reduced galactokinase (GALK).
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Pathophysiology
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Mutation in GALK gene → inability to phosphorylate galactose to galactose‑1‑phosphate → galactose accumulates in blood (galactosemia) and spills into urine (galactosuria).
Aldose reductase converts excess galactose to galactitol in lens → osmotic cataracts. Unlike classic galactosemia, no accumulation of galactose‑1‑phosphate in tissues, so hepatotoxicity and sepsis do not occur.
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Presentation
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Infant with failure to track objects or develop a social smile; bilateral cataracts often early infancy; otherwise generally benign.
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Diagnosis
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Reducing substances in urine; ↑ serum galactose; normal/low galactose‑1‑phosphate; molecular GALK testing.
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Management
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Exclude galactose and lactose (galactose + glucose) from diet; cataract surgery if visual axis obscured.
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Epidemiology
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Rare; prevalence ~1 : 30 000–60 000 live births; more common in Roma population.
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Tags
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