– C12orf53 is mainly expressed in adult brain and cerebellum. It also can be detected in fetal brain and virtually no expression in spleen, heart, kidney, liver and dorsal ganglion relative to brain. C12orf53 acts as a ligand for PILRA in neural tissues, where it may be involved in immune regulation. Chromosome 12 encodes over 1,100 genes within 132 million bases. A number of skeletal deformities are linked to chromosome 12 including hypochondrogenesis, achondrogenesis and Kniest dysplasia. Noonan syndrome, which includes heart and facial developmental defects among the primary symptoms, is caused by a mutant form of PTPN11 gene product, SH-PTP2. Chromosome 12 is also home to a homeobox gene cluster which encodes crucial transcription factors for morphogenesis, and the natural killer complex gene cluster encoding C-type lectin proteins which mediate the NK cell response to MHC class I interaction.