FREQUENTLY ASKED QUESTIONS (FAQs)
How is Duarte Galactosemia (DG) diagnosed?
Most infants diagnosed with DG in the United States are detected by newborn screening (NBS) on
the basis of low galactose-1-phosphate uridylyltransferase (GALT) enzyme activity and/or high
galactose metabolites. DG can also be detected by genetic testing. Receiving a positive NBS result for
galactosemia does not confirm a diagnosis of classic or Duarte galactosemia; a diagnosis must be
confirmed by follow-up testing.
How is Duarte Galactosemia different from Classic Galactosemia?
DG differs from classic galactosemia in that patients with DG have partial GALT deficiency
whereas patients with classic galactosemia have complete, or almost complete, GALT deficiency.
How did my baby get DG?
DG is a genetic condition; this means it is inherited and not caused by environmental exposures. A
child with DG inherited variant copies of their GALT gene from both parents. A child with DG has
one copy of GALT that carries a severe, or G mutation, and one copy that carries a very mild, or D
(D2) mutation. Without testing the parents it is not possible to know which parent contributed which
copy of the GALT gene.
My child has DG. What should I feed him?
There is no broadly accepted standard of care for infants with DG, so recommendations may vary
by provider. Some healthcare providers recommend partial to complete dietary restriction of milk
and other high galactose foods for infants with DG, but others do not. Because children with DG
develop increased tolerance for dietary galactose as they grow, few healthcare providers
recommend dietary restriction of galactose beyond the first year of life. Information about the
What is galactose and where does it come from?
Galactose is a small natural sugar. It is found at high levels in milk, including breast milk, cow's milk,
other animal milks, milk-based formula, and many dairy products like yogurt or ice cream. The
galactose in milk and dairy products is usually present in the form of lactose, or milk sugar, which is
broken down by normal digestion to release galactose and another sugar called glucose. Galactose
is also found at low levels in many other foods, like legumes, and is made at low levels in the human
body. A person with normal GALT activity, who does not have galactosemia, is able to convert
galactose into other useful compounds in their body, or break it down for energy. A person with
impaired GALT activity may have difficulty converting or breaking down galactose.
Does DG have any symptoms?
Infants with DG who consume breast milk or formula containing the milk sugar, lactose, generally
do not show symptoms; however, some infants with DG may show acute symptoms, like jaundice,
vomiting, or diarrhea, after drinking milk. Infants who do show these acute symptoms typically
recover quickly when switched to a low-galactose diet, such as soy formula.
How should I follow up with my child's healthcare provider?
Ask your child's healthcare provider for their recommendation. If your child was not put on a
special diet the doctor may (or may not) recommend a follow-up lab test of blood or urine to check
for galactose metabolites, to make sure these are normalizing. If your child was put on a special
(galactose-restricted) diet the doctor may recommend a galactose challenge sometime around
the child’s first birthday to see if the diet can be relaxed. Most infants with DG who are followed by a
metabolic specialist are discharged from follow-up after a successful galactose challenge.
What is a galactose challenge?
A galactose challenge is a simple test designed to show whether a child is able to metabolize
dietary galactose sufficiently to prevent the abnormal build-up of galactose metabolites, generally
measured as galactose-1-phosphate (Gal-1P) in the blood or galactitol in the urine. For a child with
DG who showed elevated galactose metabolites at diagnosis, this test can be used to see if the
child's ability to process galactose has improved enough over time to discontinue dietary galactose
restriction. To read more about a galactose challenge, click here.