Current proteomic approaches for MS investigations in ASD. Several studies have suggested the causality of ASD to be of genetic and/or epigenetic origin as well as to involve exogenous toxicants (metals, environmental contaminants. MS studies have therefore initially focused on identification of exogenous substances. The proteome, which constitutes the most dynamic entity in human physiology, has not been as extensively studied. Mass spectrometry can also be used for the analysis of the proteome of ASD samples. This includes modifications of DNA, such as methylation or histone modification, qualitative proteomics, which identify protein patterns in controls versus ASD without necessarily implicating specific proteins and ASD proteome identification. This last area of study may be particularly promising for shedding light on ASD etiology or providing potential diagnostic biomarkers.