Autism is a neuro-developmental disorder characterized by deficits in social interaction and communication as well as restricted interests or repetitive behaviors. Cytogenetic studies have implicated large chromosomal aberrations in the etiology of approximately 5–7% of autism patients, and the recent advent of array-based techniques allows the exploration of submicroscopic copy number variations (CNVs). We genotyped a 14-year-old boy with autism, spherocytosis and other physical dysmorphia, his parents, and two non-autistic siblings with the Illumina Human 1M Beadchip as part of a study of the molecular genetics of autism and determined copy number variants using the PennCNV algorithm. We identified and validated a de novo 1.5 Mb microdeletion of 14q23.2-23.3 in our autistic patient. This region contains 15 genes, including spectrin beta (SPTB), encoding a cytoskeletal protein previously associated with spherocytosis, methylenetetrahydrofolate dehydrogenase 1 (MTHFD1), a folate metabolizing enzyme previously associated with bipoloar disorder and schizophrenia, pleckstrin homology domain-containing family G member 3 (PLEKHG3), a guanide nucleotide exchange enriched in the brain, and churchill domain containing protein 1 (CHURC1), homologs of which regulate neuronal development in model organisms. While a similar deletion has previously been reported in a family with spherocytosis, severe learning disabilities, and mild mental retardation, this is the first implication of chr14q23.2-23.3 in the etiology of autism and points to MTHFD1, PLEKHG3, and CHURC1 as potential candidate genes contributing to autism risk. Autism Res2011,4:221–227. © 2011 International Society for Autism Research, Wiley Periodicals, Inc.