Galactosemia

A genetic defect characterized by the inability to metabolize.

Galactosemia is an inborn error of metabolism that results in an accumulation of galactose in the blood, tissue, and urine. Galactosemia is caused by an autosomal recessive gene, and heterozygotes for the trait exhibit reduced enzyme activity. Three types are known, each due to a specific enzyme deficit: (a) Classic galactosemia, the most prevalent and most severe form, occurs in approximately 1 in 70,000 births and is attributed to a marked deficiency of galactose-1-phosphate uridyl transferase; (b) Galactokinase deficiency, less severe, occurs in 1 in 155,000 births and leads to the development of cataracts; (c) A rare form, with no clear clinical abnormalities, is attributed to a deficit of EDP-glucose-4-epimerase (Hug, 1979). Classic galactosemia accounts for approximately 95% of cases.

A rare genetic disorder of the autosomal recessive type, a kind of metabolic disorder that results from the lack of a key liver enzyme (galactose-1-phosphate uridyl transferase), making the body unable to break down galactose, part of the milk sugar lactose. If not quickly recognized and treated, galactosemia soon causes failure to thrive and a variety of specific consequences, including cirrhosis of the liver, jaundice, cataracts, and mental retardation. Various medical tests for galactosemia can be performed, from the child’s first week of life, using blood and urine specimens. Treatment simply involves lifelong avoidance of normal milk, substituting lactose-free milk when available. If the condition is diagnosed late, however, some damage may be irreversible.

Inherited (autosomal recessive) disease in which a deficiency in or absence of the enzyme (galactose-1-phosphate uridyl transferase) necessary for the metabolism of galactose to glucose results in galactose accumulation, leading to mental retardation, spleen and liver enlargement, cataract formation, and other abnormalities. Symptoms of vomiting, diarrhea, and poor weight gain typically develop shortly after birth. The disease can be diagnosed through blood and urine tests; treatment is a galactose- free diet.

An inborn inability to utilize the sugar galactose, which in consequence accumulates in the blood. Untreated, affected infants fail to thrive and become mentally retarded, but if galactose is eliminated from the diet growth and development may be normal.

An autosomal recessive disorder marked by an inability to metabolize galactose because of a congenital absence of one of two enzymes needed to convert galactose to glucose. The diagnosis is confirmed by testing the newborn’s urine for non-carbohydrate reducing substances or more accurately by tests for the missing enzymes in blood cells. The infant with galactosemia will fail to thrive within a week after birth due to anorexia, vomiting, and diarrhea unless galactose and lactose are removed from the diet. If untreated, the disease may progress to starvation and death. Untreated children who do survive usually fail to grow, are mentally retarded, and have cataracts. If galactose is excluded from the diet early in life, the child may live to adulthood but suffer reproductive and brain disorders. Galactosemia can be diagnosed in utero by amniocentesis. If a pregnant woman is a known carrier, it is advisable that she exclude lactose and galactose from her diet.