Ataxin 2 binding protein 1 (A2BP1 aka FOX1, RBFOX1) is an RNA binding protein responsible for regulation of pre-mRNA splicing events in a number of critical developmental genes expressed in muscle, heart and neuronal cells [Shibata et al. (2000); Mamm Genome 12:595–601; Jin et al. (2003); EMBO J 22:905–912; Underwood et al. (2005); Mol Cell Biol 25:10005–10016]. Rare copy number abnormalities of A2BP1 have been previously associated with cognitive impairment, attention deficit disorder and autism [Martin et al. (2007); Am J Med Gen Part B 144B:869–876; Elia et al. (2010); Mol Psychiatry 15:637–646.]. Using a 1M Illumina SNP microarray, we identified a 1.3 kb deletion in A2BP1, which was subsequently validated by quantitative PCR. Here we present an in depth case study of an individual with autism and mild developmental hemiparesis in whom the deletion was detected. This study provides further support for the possible role of rare copy number variants in A2BP1 in the development of autism and associated motor asymmetries. © 2012 Wiley Periodicals, Inc.