Lactose is an important source of calories for most babies, whether from breast milk or formula. For babies with galactosemia, lactose becomes a poison.
Lactose, or milk sugar, is made up of two simple sugars: glucose and galactose. Classic galactosemia is a condition where children lack the enzyme necessary to process galactose. Byproducts of galactose build up in the blood and are toxic to the kidney, liver, and brain. Also, byproducts of galactose can destroy ovaries (but not testicles, for unknown reasons).
Galactose is found in the diet primarily as lactose (in breast milk, milk-based formula, milk, cheese, butter, and many nutritional and pharmaceutical extenders). Galactose is now known to be present in many foods that do not contain lactose, especially beans and peas.
Classic galactosemia is a rare recessive genetic disorder. The child with classic galactosemia inherits a gene for galactosemia from both parents, who are carriers.
Children with classic galactosemia get very sick – unless lactose is removed from the diet. Most die during infancy if it is not identified and treated. Common symptoms include jaundice, feeding difficulties, vomiting, poor weight gain, irritability, lethargy, seizures, cataracts, and mental retardation. The liver and spleen are usually enlarged.
Serious E. coli infections are more common in newborns with galactosemia. In fact, the infection may be diagnosed before the galactosemia.
Adolescent girls with galactosemia will usually not begin monthly periods.
It is a lifelong condition.
Widespread newborn screening in the United States has made undetected galactosemia uncommon. For those who have not been screened, a blood test or urine test can screen for the condition. Most people with galactosemia will develop obvious symptoms in infancy.
It is treated by removing lactose from the diet. Lactose is not a necessary part of the diet. Soy formulas are often used for babies. When babies begin solid foods, other sources of galactose must be avoided.
Removing galactose from the diet may prevent further damage to the kidney, liver, and brain. Cataracts go away, and growth problems resolve. Ovarian failure and learning problems are still common.
Strict observance of the diet does not always go along with the best outcome, suggesting either some damage before birth, or other factors involved.
Galactosemia is not preventable, but further damage is often preventable by removing galactose from the diet.