AMY1A encodes salivary alpha-amylase, a calcium-binding enzyme that initiates starch digestion in the oral cavity 1. The enzyme catalyzes hydrolysis of internal (1→4)-alpha-D-glucosidic bonds in starch, producing maltose, isomaltose, glucose, and dextrins 1. AMY1A function is significantly influenced by copy number variation (CNV). Individuals with higher AMY1A copy numbers show increased serum amylase enzymatic activity 2. Copy number expansions have been evolutionarily selected in populations consuming high-starch diets, with haplotypes containing more than three AMY1A copies increasing in frequency among European farmers over the past 4000 years 3. AMY1A CNV has disease relevance in metabolic disorders. Higher AMY1A copy numbers are associated with reduced obesity risk, particularly in children consuming medium-to-high starch diets 2. Additionally, very high AMY1A copy numbers (≥10) correlate with decreased Alzheimer's dementia hazard ratio and improved memory performance, potentially through enhanced brain alpha-amylase activity 4. CNV also influences broader cardiometabolic risk factors including glucose homeostasis, lipid metabolism, and gut microbiome composition 5. Clinically, AMY1A serves as a diagnostic immunohistochemical marker, showing 100% sensitivity and 96.75% specificity in distinguishing benign oncocytoma from chr1 renal cell carcinoma 6.