Well, Lianjie and I left the bedside and went back to the nurse station, met up with the metabolic disorders pediatric fellow, and plugged into the net.
None of us had seen a rash of propionic acidemia before, but the special diet and chronic nature of the rash led us to suspect acrodermatitis enteropathica.
The Online Mendelian Inheritance in Man web site descibes many human genes and genetic disorders from Victor McKusicks classic textbook. Unlike a printed book, however, it is more rapidly updated, totally search-able, and thru hypertext links, can give you recent references on rare disorders.
It turns out these organic acidurias, methymalonic and propionic acidemia, can rob keratinocytes of isoleucine, valine, methionine and threonine. The cutanous eruption can mimic zinc-defiency and acrodermatitis enteropathica.
We found he had normal alkaline phosphatase, pending zinc levels, recommended some modifications to his diet.