Galactokinase deficiency

A rare genetic metabolic disorder

Classification
External resources

Galactokinase deficiency is a rare autosomal recessive metabolic disorder that affects the body's ability to process the sugar galactose. It is one of the types of galactosemia, a condition characterized by the inability to properly metabolize galactose, a sugar found in milk and other dairy products.

Pathophysiology

Galactokinase deficiency is caused by mutations in the GALK1 gene, which encodes the enzyme galactokinase. This enzyme is responsible for the phosphorylation of galactose to galactose-1-phosphate, the first step in the Leloir pathway of galactose metabolism. In individuals with galactokinase deficiency, the lack of functional enzyme leads to the accumulation of galactose in the blood and tissues.

Clinical Features

The most common clinical manifestation of galactokinase deficiency is the development of cataracts in infancy or early childhood. Cataracts occur due to the accumulation of galactitol, a sugar alcohol derived from galactose, in the lens of the eye. Other symptoms may include failure to thrive, hepatomegaly, and developmental delay, although these are less common.

Diagnosis

Diagnosis of galactokinase deficiency is typically made through newborn screening programs that test for elevated levels of galactose in the blood. Confirmatory testing involves measuring the activity of galactokinase in red blood cells or identifying mutations in the GALK1 gene through genetic testing.

Treatment

The primary treatment for galactokinase deficiency is a galactose-restricted diet, which involves avoiding foods that contain galactose, such as milk and dairy products. Early dietary intervention can prevent the development of cataracts and other complications. Regular monitoring of galactose levels in the blood is also recommended to ensure dietary compliance.

Prognosis

With early diagnosis and appropriate dietary management, individuals with galactokinase deficiency can lead normal, healthy lives. However, if left untreated, the condition can lead to significant visual impairment due to cataract formation.

Related pages

• Galactosemia
• Metabolic disorder
• Autosomal recessive disorder
• Cataract