California Newborn Screening Program
Galactose is a carbohydrate found in human milk and dairy products. Defects in the galactose metabolic pathway lead to various forms of galactosemia, which literally means "the presence of galactose in the blood."
a. Classical galactosemia involves a deficiency in the transferase enzyme (galactose-1-phosphate uridyltransferase, also known as GALT). This enzyme is found in erythrocytes (red blood cells) and other tissues. The incidence of this disorder in California is 1:73,000. It is an autosomal recessive disorder. The Newborn Screening Program is designed to detect this form of galactosemia.
In its classical form, there is virtually no detectable transferase activity. Galactose accumulates in the blood and urine; galactose-1-phosphate is present in the erythrocytes and other tissue cells; and galactitol (a galactose metabolite) is found in urine, ocular lenses, and other tissues.
Neonatal symptoms may include:
- liver damage, jaundice
- failure to thrive
- lethargy, poor sucking
- sepsis, usually E. coli, frequently leading to death
Post-neonatal symptoms, if left untreated, include:
- mental retardation
- cataracts (can also be present at birth)
- Fanconi's syndrome (metabolic bone disease, renal dysfunction)
Post-neonatal symptoms, even with prompt treatment, can include:
- abnormal speech
- developmental and growth failure
- decreased reproductive capacity, especially ovarian failure
b. Variants exist where the transferase deficiency is partial, rather than total. The clinical findings range, depending on the variant. The Duarte gene is the most commonly encountered one. The gene for the Duarte variant confers 50% of the enzyme activity of the normal gene.
The treatment for classical galactosemia consists of a lactose-free diet implemented as soon as possible and continued throughout life. Breast milk and milk-based formula are inappropriate; soy-based formulas (Isomil®, Nursoy®, Prosobee®, I-Soyalac®) and/or meat-based formula during infancy will provide adequate and safe nutrition.
Newborns with galactosemia are referred to metabolic physicians at a California Children's Service (CCS) Center for follow-up.
Parents' Guide to Galactosemia Part I (PDF)
Parents' Guide to Galactosemia Part II (PDF)