As a dietitian, I could readily identify MSUD as "Maple Syrup Urine Disease", an inborn error of metabolism. As more of an LC for the past 15 years rather than an RD, I had to do some digging to find out what it specifically meant!! Here's what I found out: Also known as branched-chain ketoaciduria, MSUD infants are identified shortly after birth by the maple syrup ordor of the body and urine. They become ill shortly after birth - feeding difficulties, vomiting, convulsions are followed by death. The branched-chain amino acids - valine, leucine and isoleucine - tranform and turn into keto acids. In this inborn error of metabolism, these keto acids cannot undergo oxidative decarboxylation and the keto acids along with free amino acids build up in the blood and subsequently spill over into the urine. Treatment must be instituted early in life to avoid mental retardation. Control is much more difficult than in the case of PKU. Plasma levels of each amino acid must be regulated individually. The levels are not easily stabilized, especially in times of illness. Peritoneal dialysis may be used to reduce blood levels of the amino acids. As far as diet, all of the three amino acids are essential, meaning they must be supplied in the diet for normal growth and development - they will not be manufactured by the body. In normal infants, excesses are not a problem. In MSUD, the baby must get the amount required for normal growthe and development, but not extra. A special formula which is void of leucine, isoleucine and valine can be used and then the minimum amount of the amino acids added back to the diet along with monitoring serum blood levels. As far as breastfeeding is concerned, BM contains all of these amino acids, naturally, because they are essential amino acids needed for growth. From the tables in Lawrence, it appears mature milk is lower in the amino acids than colustrum (p. 505 3rd edition). I suspect mother nature has provided more than the minimum and this could cause a problem for the MSUD infant. It might be possible to try BF after the mature milk is in and monitoring the serum levels as indicated above. I do have my doubts, though and think the levels may be too high for a MSUD infant to handle on a regular basis. Hope this is helpful. Theresa Gutsch, Ms, RD, CLE