ROM1 (retinal outer segment membrane protein 1) is a photoreceptor-specific integral membrane protein located at the rims of rod outer segment (ROS) disks 1. ROM1 functions as a structural component essential for ROS morphogenesis and disk organization, working cooperatively with its homologue PRPH2 (peripherin 2) to maintain ROS curved disk structure and diameter 1. The two proteins share 47% sequence identity in their central hydrophilic domain and likely form non-covalent associations in vivo 1. ROM1 is located on chromosome 11 2. ROM1 is primarily associated with digenic retinitis pigmentosa (RP), where mutations in both ROM1 and PRPH2 together cause disease, though ROM1 mutations alone have not been definitively linked to RP 3. More significantly, ROM1 acts as a disease modifier in PRPH2-associated retinal degeneration, modulating phenotypic severity 45. ROM1 variants can trans-modify ABCA4/Stargardt disease, with rare variants enriched in patients (1.3% vs 0.3% in controls) 6. Functionally, ROM1 influences PRPH2 complex formation, ER retention, and protein stability, with mutation-specific effects on disease presentation ranging from amelioration to exacerbation 45. ROM1 was recently identified as a potential cross-tissue molecular target associated with lung function traits 7.