How is Duarte Galactosemia (DG) diagnosed?
How is Duarte Galactosemia different from Classic Galactosemia?
How did my baby get DG?
My child has DG. What should I feed him?
What is galactose and where does it come from?
Do infants with DG show any symptoms?
How should I follow up with my child's healthcare provider?
What is a galactose challenge?

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
galactose content of different foods can be found on our Nutritional Information page.

Does cooking milk get rid of galactose?
No. Heating can change some components of milk in ways that might make them more or less
problematic for someone with a milk sensitivity, but galactose is not eliminated by boiling or normal
cooking processes.

Is there any down side of restricting dairy for an infant?
Yes. Decades of research have documented the many health benefits of breast milk for infants who do
not have a milk sensitivity; restricting dairy for an infant who does not have a milk sensitivity prevents
the baby from receiving those benefits.

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 cottage cheese 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.

Do infants with DG show any symptoms?
Most infants with DG who consume breast milk or formula containing milk do not show symptoms.
However, some infants with DG may show symptoms like jaundice, vomiting, or diarrhea, after
drinking milk. Infants who do show these symptoms typically recover quickly when switched to a
non-dairy diet, such as soy formula. There are many reasons why an infant may show
sensitivity to breast or cow’s milk, such as a milk protein allergy, and these sensitivities can occur in
children with DG as well as children without DG. In fact, many causes of milk sensitivity are much
more common than DG; for example, approximately 1 in 100 infants are born with a milk protein
allergy, compared to only 1 in 4000 born with DG. This means that if a baby with DG shows
symptoms of milk sensitivity the family and healthcare team should consider switching the baby to a
non-dairy formula, but the cause of the sensitivity may not be DG.

Are older children with DG at increased risk for developmental problems?
A recent study (Carlock et al, Pediatrics Dec 2018, e20182516; DOI: 10.1542/peds.2018-2516) .
tested 350 children, ages 6-12 years old, for 73 outcomes representing 5 different developmental
domains. The prevalence of developmental problems detected was not significantly different between
the 206 children in this study who had DG and the 144 children who did not have DG. To be clear, some
children in both groups did show developmental problems, but children with DG did not show a higher
rate of these developmental problems than did the children without DG. This result indicates that DG
was unlikely to be the cause of these developmental problems. Please click here for more information.

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.