PCDHB1 encodes a calcium-dependent cell-adhesion protein involved in establishing and maintaining neuronal connections in the brain. As a protocadherin family member, PCDHB1 functions in cell adhesion through calcium-dependent mechanisms at the plasma membrane. PCDHB1 is transcriptionally regulated by MeCP2 (methyl-CpG-binding protein 2), which binds to upstream regulatory regions and suppresses PCDHB1 expression 1. In Rett syndrome, mutations in MECP2 lead to aberrant upregulation of PCDHB1 in affected brain tissues, suggesting that dysregulation of this neuronal adhesion molecule contributes to the neurological features of this neurodevelopmental disorder 1. Beyond neurological function, PCDHB1 is recurrently mutated in early gastric carcinoma and may be involved in early stages of gastric cancer development 2. Additionally, methylation patterns at CpG sites associated with PCDHB1 serve as epigenetic markers for age estimation in forensic applications 3. These findings indicate that PCDHB1 plays roles in both normal neuronal development through adhesion-mediated mechanisms and potentially in cancer-related cellular dysfunction when dysregulated.