High-resolution electrophoretic methods and sensitive
protein-detection techniques permit new approaches to understanding and diagnosis of the
inborn errors of metabolism. These approaches encompass: the search for
protein alterations that represent primary mutations effects; observation of alterations in
protein patterns due to secondary effects, as might occur in major metabolic pathway abnormalities; and identification of
protein polymorphisms that are genetically linked to an inborn
metabolic disease. With the aid of computer analysis of the electrophoretograms, all three approaches are being developed.
Protein density and position are evaluated with an interactive computer program that requires that gel
polypeptides be indexed by the investigator.
Proteins on the
gels are made visible with an inexpensive, rapid
silver stain, which can be used quantitatively. The
Lesch-Nyhan syndrome, one of a few neuropsychiatric diseases for which the molecular defect is known, was chosen for study with these techniques. Four hundred
proteins were analyzed for positional or quantitative variation. Eleven significant (2p less than 0.01) quantitative differences were found in autoradiograms from
gels of
phytohemagglutinin-stimulated lymphocytes. Specific patterns of
polypeptide variation are now being sought in an expanded clinical study primarily focusing on
Huntington's disease. Large studies are required to establish the specificity of observed alterations. As the number and variety of analyses increase, a correlative catalog of molecular variation and polymorphism will be generated.