Galactosemia: Causes, Symptoms

Galactosemia

It is an inherited disorder, in which there is inability to convert galactose to glucose in a normal manner. The incidence of this disease is about 1 in 18,000 live births.

1.  Causes

Enzyme deficiency in galactose metabolic pathway causes galactosemia. The pathway for conversion of galactose to glucose is shown in figure 7.1.

In galactosemia, there is inability to metabolize galactose which may be caused by the enzyme deficiency of a = galactokinase, b = UDP Galactose 1 - phosphate uridyl transferase.

2.  Symptoms

The deficiency of galactose 1 - phosphate uridyl transferase is clinically important. Due to the enzyme defect galactose accumulates in blood and is reduced by aldose reductase in the eye to the corresponding galactitol which causes cataract.

The general condition is more severe if it is due to a defect in galactose 1 - phosphate uridyl tranferase, since galactose 1- phosphate accumulates and depletes the liver of inorganic phosphate. Ultimately, liver failure and mental deterioration results.

Infants appear normal at birth but later they show failure to thrive and become lethargic. They have frequent vomitting and hypoglycemia. After 2 - 3 months of age the liver may show fatty infiltration and lead to cirrhosis (non functioning of liver cells). Galactosemia at this age is associated with mental retardation due to accumulation of galactose and galactose 1 - phosphate in cerebral cortex. So, the galactosemic child fails to grow and suffer from liver damage and mental retardation.