The 15q11.2 (BP1–BP2) deletion (sometimes referred to as the Burnside-Butler syndrome susceptibility locus) has previously been associated with phenotypes including developmental delay, autism, schizophrenia and CVM; the great majority of the evidence regarding the deletion thus far originates from cohorts specifically selected for one or other of those phenotypes. This evidence concerns the gene IGFBP2 and Global developmental delay.