Calcineurin is a protein phosphatase with an important role in signal transduction; its calcium-binding regulatory subunit, calcineurin B, is widely present in the brain and is coded by the PPP3R1 gene which was mapped recently to human chromosome 2. Calcineurin has long been considered a candidate for psychiatric and/or monogenic brain disorders. The present study reports the intron-exon structure of the PPP3R1 gene with the proximal intronic sequences, its genetic mapping to D25358-D251778 on chromosome 2p15, and its exclusion in a genetic disorder mapped proximal to this locus.