In persons with autism and similar illnesses, post-mortem examinations allow for a direct examination of brain tissue. Several review publications have focused on certain elements of post-mortem abnormalities, but none has compiled the full body of post-mortem research. In this paper, we examine the evidence from post-mortem studies of autism and associated illnesses with autistic characteristics. Despite the fact that the literature is made up of a small number of research with small sample sizes, numerous strikingly consistent conclusions may be found. The layering of the cortex is essentially unaffected, although there are consistent reductions in the number of minicolumns and abnormal myelination. Abberant synaptic, metabolic, proliferative, apoptotic, and immunological pathways have all been implicated by transcriptomics. Non-coding RNA, abnormal epigenetic profiles, GABAergic, glutamatergic, and glial dysfunction are all implicated in autism pathophysiology by sufficient repeatable evidence. Overall, the cerebellum and frontal cortex are the most frequently implicated, with significant region-specific changes occasionally revealed. The research on related illnesses including Rett syndrome, Fragile X, and copy number variants (CNVs) that predispose to autism is notably scarce and contradictory. Larger trials are needed that are matched for gender, developmental stage, co-morbidities, and pharmacological treatment.
