Galactosemia is caused by a lack of one of the enzymes needed to metabolize the sugar in milk.
Symptoms include vomiting, jaundice, diarrhea, and abnormal growth.
The diagnosis is based on blood and urine tests.
Even with adequate treatment, affected children still develop mental and physical problems.
Treatment involves completely eliminating milk and milk products from the diet.
Galactose is a sugar that is present in milk as part of lactose and in some fruits and vegetables. Deficiency of a certain enzyme can alter the breaking down (metabolizing) of galactose, which can lead to high levels of galactose in the blood (galactosemia). There are different forms of galactosemia, but the most common and the most severe form is referred to as classic galactosemia.
There are different types of inherited disorders Inheritance of Single-Gene Disorders Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more . In galactosemia, both parents of the affected child carry a copy of the abnormal gene. Because usually two copies of the abnormal gene are necessary for the disorder to occur, usually neither parent has the disorder. (See also Overview of Hereditary Metabolic Disorders Overview of Hereditary Metabolic Disorders Hereditary metabolic disorders are inherited genetic conditions that cause metabolism problems. Heredity is the passing of genes from one generation to the next. Children inherit their parents'... read more .)
Newborns with galactosemia seem normal at first but, within a few days or weeks of consuming breast milk or lactose-containing formula, lose their appetite, vomit, become jaundiced, have diarrhea, and stop growing normally. White blood cell function is affected, and serious infections can develop.
Many children also have cataracts. Girls often have ovaries that do not function, and only a few are able to conceive naturally. Boys, however, have normal testicular function.
If treatment is delayed, affected children remain short and become intellectually disabled Intellectual Disability Intellectual disability is significantly below average intellectual functioning present from birth or early infancy, causing limitations in the ability to conduct normal activities of daily... read more or may die.
Galactosemia is detectable with a blood test. This test is done as a routine screening test for newborns Newborn Screening Tests Many serious disorders that are not apparent at birth can nonetheless be detected by various screening tests. Early diagnosis and prompt treatment can reduce or prevent many disorders that may... read more in all states in the United States. Before conception, adults with a sibling or child known to have the disorder can be tested to find out whether they carry the gene that causes the disease. If two carriers conceive a child, that child has a 1 in 4 chance of being born with the disease. Carriers Carrier Screening Genetic screening is used to determine whether a couple is at increased risk of having a baby with a hereditary genetic disorder. Hereditary genetic disorders are disorders of chromosomes or... read more are people who have an abnormal gene for a disorder but who do not have symptoms or visible evidence of the disorder.
Another test is done to look for elevated levels of galactose in the urine.
If galactosemia is recognized at birth and adequately treated, liver and kidney problems do not develop, and initial mental development is normal. However, even with adequate treatment, children with galactosemia may have a lower intelligence quotient (IQ) than their siblings, and they often develop speech and balance problems during adolescence.
Galactosemia is treated by completely eliminating milk and milk products—the main source of galactose—from an affected child’s diet. Because galactose is present in both human breast milk and cow's milk–based infant formulas, infants are typically fed a soy-based infant formula after diagnosis. People who have the disorder must restrict galactose intake throughout life. Galactose is also present to a much lesser extent in some fruits, vegetables, and sea products, such as seaweed, but doctors have not found that it helps people to avoid these foods. It is also used as a sweetener in many foods. Many people need to take calcium and vitamin supplements.