Galactose-1-phosphate uridylyltransferase deficiency

Beta-D-Galactopyranose

Galactose metabolism

Galactose Metabolism GALT.png

autorecessive

Galactose-1-phosphate uridylyltransferase deficiency

Galactose-1-phosphate uridylyltransferase deficiency (GALT deficiency) is a genetic disorder that affects the body's ability to process the simple sugar galactose. It is a type of galactosemia, specifically known as classic galactosemia or Type I galactosemia. This condition is caused by mutations in the GALT gene, which provides instructions for making the enzyme galactose-1-phosphate uridylyltransferase.

Pathophysiology

In individuals with GALT deficiency, the enzyme galactose-1-phosphate uridylyltransferase is either absent or not functioning properly. This enzyme is crucial for the conversion of galactose-1-phosphate into UDP-galactose and glucose-1-phosphate. As a result, galactose-1-phosphate accumulates in various tissues, leading to toxic effects and the symptoms associated with the disorder.

Symptoms

Symptoms of GALT deficiency typically appear shortly after birth and can include:

• Jaundice
• Hepatomegaly (enlarged liver)
• Vomiting
• Poor feeding
• Failure to thrive
• Lethargy
• Sepsis
• Cataracts
• Developmental delay

Diagnosis

Diagnosis of GALT deficiency is usually made through newborn screening programs that test for elevated levels of galactose or galactose-1-phosphate in the blood. Confirmatory testing involves measuring the activity of the galactose-1-phosphate uridylyltransferase enzyme in red blood cells or identifying mutations in the GALT gene through genetic testing.

Treatment

The primary treatment for GALT deficiency is a strict galactose-free diet, which involves eliminating lactose and galactose from the diet. This dietary restriction helps prevent the accumulation of toxic substances and alleviates symptoms. Lifelong adherence to the diet is necessary to avoid complications.

Prognosis

With early diagnosis and strict dietary management, individuals with GALT deficiency can lead relatively normal lives. However, some may still experience long-term complications such as speech delays, learning disabilities, and ovarian failure in females.

See also

• Galactosemia
• GALT gene
• Metabolic disorder
• Newborn screening