MCTP2 (multiple C2 and transmembrane domain containing 2) is a calcium-binding transmembrane protein with critical roles in cardiac development and neurological function. Primary function: MCTP2 is a dosage-sensitive gene required for cardiac outflow tract (OT) development 1. The protein contains multiple C2 domains and transmembrane regions, enabling calcium-dependent phospholipid binding [GO annotations]. Mechanism: MCTP2 functions in lipid droplet biogenesis at specialized ER sites marked by reticulon-like proteins 2, and regulates neurotransmitter secretion through calcium-mediated signaling [GO annotations]. Disease relevance: MCTP2 mutations cause congenital prosopagnosia (face blindness), with frameshift mutations (S80fs) showing complete cosegregation with impaired face recognition and reduced repetition suppression in the fusiform face area 3. Heterozygous deletions and duplications cause coarctation of the aorta (CoA) and hypoplastic left heart syndrome (HLHS) 1. Clinical significance: MCTP2 is upregulated in recurrent glioblastoma, correlating with poor survival and immune checkpoint marker expression (PD-L1, CTLA-4), suggesting roles in immune evasion and drug resistance 4. MCTP2 variants also associate with Lewy body pathology 5 and promote tumor progression in oral squamous cell carcinoma through EMT-related mechanisms 6.