TMEM25 is a novel member of the immunoglobulin superfamily. Immunoglobulin superfamily members are implicated in immune responses, growth factor signaling, and cell adhesion. TMEM25 contains 1 Ig-like (immunoglobulin-like) domain and is a target of pharmacogenomics in the field of oncology and regenerative medicine. TMEM25 isoform 1, consisting of exons 1-9, encoded a 366-aa transmembrane protein. TMEM25 isoform 2, consisting of exons 1-4 and 6-9, encoded a 322-aa secreted protein. TMEM25 mRNA was expressed in brain, including cerebellar cortex and hippocampus, as well as in neuroblastoma, brain tumors, and gastric cancer. Human TMEM25 gene was located at the 11q23.3 oncogenomic recombination hotspot around the MLL amplicon and the neuroblastoma deleted region.