GPM6B and Down syndrome: Amongst these TLX-dependent transcripts were several genes involved in central nervous system function (Fig 4D), including a synaptic adhesion molecule (CADM1); the neuronal signal transducer, chimerin-1 (CHN1); a serotonin binding glycoprotein (GPM6B); and sorting nexin family member 27 (SNX27), a gene recently shown to regulate developmental and cognitive impairment in Down syndrome [48].