SAMD7 (sterile alpha motif domain containing 7) is a Polycomb repressive complex 1 (PRC1) component essential for photoreceptor cell identity and function 1. As a Crx-regulated transcriptional repressor, SAMD7 suppresses non-rod gene expression in developing rod photoreceptors by establishing repressive epigenetic marks, including H3K27me3 and H2AK119ub, thereby silencing transcription of inappropriate genes 2. SAMD7 localizes to both cytoplasm and nucleus, with particular abundance in retinal outer nuclear layer cells and inner nuclear layer cells 21. Clinically, bi-allelic SAMD7 mutations cause autosomal-recessive macular dystrophy with or without cone dysfunction, with variants affecting splicing or altering Crx-dependent repressive activity 1. Non-coding regulatory variants in Crx-binding regions of SAMD7 may contribute to retinitis pigmentosa phenotypes 3. Beyond ophthalmology, SAMD7 expression is modulated by vitamin D signaling in hepatic stellate cells 4 and genetic variants affecting SAMD7 transcription associate with gestational diabetes mellitus susceptibility 5. These findings demonstrate SAMD7's critical role in photoreceptor development and broader involvement in metabolic and immune processes.