Proteomic approach for the elucidation of biological defects in autism

Proteomic-based approaches, which examine expressed proteins in tissues or cells, have great potential in the elucidation of biological defects in heterogeneous neurodevelopmental disorders such as autism. In this approach, tissue or cellular proteins from control and affected subjects are separated on two-dimensional (2-D) polyacrylamide gel electrophoresis, and those proteins that show marked changes in the concentration between control and affected subjects are identified by mass spectroscopy. This method has been successfully applied in the elucidation of the molecular biological defect in classic late-infantile neuronal ceroid lipofuscinosis (Sleat et al., 1997). Unlike the classical methods of genome-wide screening for chromosomal localization followed by positional cloning, the proteomic approach requires limited number of tissue samples and the study can be completed in a relatively short time. Currently, these methods are available for relatively abundant proteins and generally are not applicable for hydrophobic proteins because 2-D gel electrophoresis is not very effective in the analysis of hydrophobic proteins. The genetic defect results in either total loss of proteins or changes in molecular weight and/or isoelectric point will be detectable by the proteomic method. Because autism is a neurogenetic disorder, brain is the tissue of choice for proteomic study. For an oligogenic disorder such as autism, at least some of the aberrant (genes) proteins may be identified by this technology.