Elise -
I'm certainly no expert on Galactosemia, but having seen no other comments to
your note yet, I wanted to mention a few things ...
True Galactosemia is indeed extremely rare, and either you have it or you don't.
The basic problem is the essential absence (<5%) of the enzyme known as "GALT,"
which breaks down galactose into glucose. Galactose accumulates in body cells
and organs and causes damage. Babies with true Galactosemia will not tolerate
milk, and generally show liver damage, vomiting, &/or diarrhea within only a few
days. They will need to avoid milk and milk products, as well as several other
types of galactose-containing foods for life.
The confusing part is that there are variants that are not as severe as "true"
Galactosemia -- the most common is the "Duarte" variant. Just carrying a gene
for either "true" (G) or Duarte variant (D) will cause a decrease in enzyme
activity -- WHICH CAN BE PICKED UP ON THE SCREEN AS A POSITIVE. BUT -- *normal*
enzyme production far exceeds the actual need, so *depressed* enzyme activity
*may or may not* pose a problem or be something that requires treatment in the
form of dietary modification. This is where you see variations in severity.
Carrying only one "G" gene (G/N) will typically result in about 50% of "normal"
enzyme activity. Carrying one "D" gene (D/N) will cause about 25% reduction. 2
D's (D/D) is diagnosed as Duarte Galactosemia, and there is typically about 50%
of normal enzyme activity.
In our case, my husband (G/N) has had about a 50% reduction all his life from
his single "G" gene, but never had a clue until our daughter was born 6 years
ago. Had he been screened 39 years ago, he may or may not have had a positive
screen. Our oldest daughter has this same genotype and did NOT have an abnormal
screen 7 1/2 years ago.
I am a carrier for Duarte (D/N), and have always had an undetectable ~25%
decrease in GALT enzyme activity; I would have likely screened negative
"30-some" years ago. Our second daughter is a double carrier (G/D); her screen
came back positive, although she was perfectly healthy (except for some mild
jaundice that resolved quickly and without incident). Testing revealed that she
had a 78% reduction in enzyme activity (cumulative from the 2 genes she
carried), but the 22% she did have was fortunately sufficient to metabolize
almost-full-time breastmilk. The Pediatric Endocrinologist knew at first glance
of her newborn screen that she did not have true Galactosemia and ended our 2-3
day weaning period immediatly, but it took another couple of weeks to figure out
exactly what was going on. We did check her periodically to make sure that her
galactose-1-phosphate levels didn't go too high; she went from 3.4 at 2 weeks to
undetectable at 6 months. This is probably quite unusual, though, since I
understand that with this genotype, milk is typically restricted and challenged
several years later. Honestly, except for the topic coming up on Lactnet
occasionally, I really have never thought of it, and have never modified her
diet at all. Coincidentally, she is the most "milk-loving" among my 3 girls.
(We haven't genotyped the 3rd daughter to date, but her newborn screen was also
negative, so she may have either the "G" or "D" gene or neither, but most likely
not both.)
In summary -- true Galactosemia will almost certainly present clinically at
birth or very soon after, in addition to the newborn screen, and does need to be
treated urgently. Any milk intolerance at all should be suspect, especially
with a positive screen. BUT ... a newborn screen is not diagnostic, and should
be interpreted by a knowledgeable clinician and accompanied by a thorough
physical exam, especially including a check for liver or neurological damage,
and possibly an ophthalmic exam. If temporary weaning seems warranted, I agree
fully with Pat that special care should be taken to help maintain the mother's
milk supply, since there are huge odds in favor of being able to at least
partially breastfeed as soon as all the tests are in. Also, I would think that
children with enzyme activity depressed enough to show up on a state screen
should be followed to monitor galactose-1-phosphate levels, especially if
breastfeeding is resumed. I think the quote from the Breastfeeding Answer Book,
p 309 is well-put.
Sandra McMillan, RD
Saint Eugene Medical Center
Dillon SC
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