Sorry this reply is so late, I have been busy all week trying to catch
up after the fabulous ILCA conference in Acapulco.

Methylmalonic aciduria is a symptom of an inherited metabolic defect.
There are several defects that cause this symptom.  In infants with high
methylmalonic acid due to a defective transferase, administration of
high doses of cobalamin (vitamin B-12) by injection or iv will reduce
the methylmalonic acid levels.  The other half of infants with
methylmalonic aciduria have defective methylmalonic coenzyme A mutase,
which is sometimes treated by special formulas without the amino acids
isoleucine, threonine, valine, methionine; which use this pathway for
metabolism.  The infant is usually given some regular formula so they
get some of these amino acids.

Of course, breast milk has less of these amino acids than formula, but
it can be difficult to find a physician who will work with a
breastfeeding mother.  I had an infant in my practice with a cobalamin C
deficiency (one of the enzymes that changes dietary B12 to it's active
form), and the physicians insisted that the mother wean, because "we
don't know what the protein content of your milk is".  Mom was grieving
her ill infant, and did not have the energy to argue that they would
just test the baby's blood the way they would to find the right balance
of each formula to get the right balance of breastmilk and the special
formula.  This baby had both methylmalonic aciduria, and
homocysteinuria.

Any metabolic acidosis can be lethal, so it is important that this baby
be treated.  But if he or she is just missing the transferase, there is
no need to wean from the breast at all.
--
Catherine Watson Genna, IBCLC  New York City  mailto:[log in to unmask]

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