ERBB4 and schizophrenia: Previous studies have demonstrated that a haplotype consisting of three single nucleotide polymorphisms (SNPs; rs707284, rs839523 and rs7598440) in the human ErbB4 gene is associated with increased risk for schizophrenia, augmented expression of the ErbB4 CYT-1 phosphoinositide 3-kinase (PI3K)-linked isoform in the brain of patients and altered frontotemporal structural connectivity in normal humans measured with magnetic resonance imaging (MRI) techniques [6], [7], [12].