NRG1 and schizophrenia: Rs6994992 is part of the original schizophrenia-associated risk HapICE haplotype (Stefansson et al., 2002) and has been found to be associated with altered transcription factor binding and increased levels of type IV NRG1 mRNA in postmortem brain tissue (Law et al., 2006) and alteration in type IV promoter activity in in vitro receptor assays (W et al., 2007).