AMY1B encodes salivary alpha-amylase, an enzyme responsible for starch digestion with alpha-amylase activity and calcium/chloride ion binding capabilities 1. It is part of a polymorphic multigene family on chromosome 1, organized as head-to-tail repeats with variable copy numbers across human haplotypes 2. The gene shows complex genomic organization with AMY1B uniquely in reverse orientation relative to neighboring AMY1A genes 2. AMY1B expression is developmentally regulated: it is downregulated when human minor salivary gland stem cells differentiate into functional acinar and duct cells via Wnt/BMP pathway activation 3. While serum amylase can derive from non-parotid sources including liver, parotid-specific expression requires regulatory elements extending beyond 5 kb upstream and 10 kb downstream of the promoter 4. Clinically, AMY1 copy number variation correlates with metabolic phenotypes including visceral fat volume, glucose absorption, serum HDL-cholesterol, and adiponectin levels, but not insulin resistance 5. However, copy number explains only ~12-14% of salivary amylase expression variation, suggesting substantial post-transcriptional regulation 6. AMY1B maps to fragile genomic regions susceptible to RAG-mediated chr1 rearrangements in glioblastoma 7, highlighting its role in genomic instability associated with cancer.