Rare cases of genetic or epigenetic diseases can provide major insights into more common factors of the same or similar phenotypes. For example, a few genetic or epigenetic conditions can present with typical autism, including fragile X syndrome, tuberous sclerosis, mutations in the MECP2 gene (causing Rett syndrome), and mutations within chromosome 15q11-q13. There may be more patients diagnosed with autism spectrum disorders (ASD) that have mutations or epimutations involving MECP2, genes within chromosome 15q11-q13, and the loci causing fragile X syndrome and tuberous sclerosis than are currently recognized. Additionally, genes that interact with MECP2 and UBE3A are candidate genes for mutation or epimutation causing autism. This study will use in depth genotype/phenotype and epigenotype/phenotype correlations in autistic patients with known abnormalities in MECP2 and UBE3A genes and regions to provide insight into more common forms of autism. Mutation and epimutation analyses on other autism candidate genes will be performed based on their potential to explain the male predominance in autism or their relationship to the functional, biochemical, or regulatory pathways of the genes that cause disorders with phenotypes similar to ASD.