MYO1A encodes myosin IA, an actin-based motor protein primarily localized to intestinal brush border microvilli 1. The protein mediates actin filament-based movement and organelle transport through a C-terminal tail homology 1 (TH1) domain that binds phosphatidylserine and phosphoinositol 4,5-bisphosphate on microvillar membranes 1. MYO1A functions in multiple tissues beyond the intestine, including osteoblasts where it regulates cell differentiation independent of calcium transport 2, and in trophoblasts where it promotes proliferation and migration through SMURF2/Hedgehog signaling 3. MYO1A has well-established tumor suppressor activity in colorectal cancer, with frameshift mutations occurring in 32% of microsatellite-instable tumors and promoter methylation inactivating the gene in a significant proportion of cases 4. Low MYO1A expression independently predicts shorter disease-free and overall survival in colorectal cancer patients 4. MYO1A inactivation also occurs at high frequency in gastric tumors (46.8%) with mechanistic consequences including reduced protein stability and loss of membrane localization 5. Recently, MYO1A variants were functionally characterized as novel genetic causes of congenital diarrhea and enteropathy (CODE) in infants 6. However, MYO1A appears dispensable for hearing; mutations previously attributed to DFNA48 deafness co-segregate with other deafness genes and occur at population frequencies incompatible with dominant inheritance 7.