SAMD11 (sterile alpha motif domain containing 11) is a transcriptional co-repressor that plays critical roles in retinal development and photoreceptor function. The protein is strongly expressed in human retina with differential localization between cone and rod photoreceptors 1. SAMD11 functions as a component of Polycomb group (PcG) multiprotein complexes and interacts with the photoreceptor transcription factor CRX to regulate gene expression in retinal cells 1. The gene exhibits extensive alternative splicing, with up to 45 splice variants identified in humans, though functional differences between species exist as human SAMD11 shows broader tissue expression and is not directly regulated by retinal transcription factors like mouse Samd11 2. Beyond retinal function, SAMD11 regulates collagen production in fibroblasts through upregulation of PLOD1, contributing to skin rejuvenation processes 3. Disease-wise, homozygous nonsense mutations in SAMD11 cause autosomal recessive retinitis pigmentosa, confirming its essential role in photoreceptor survival 1. The gene has also been implicated in autism spectrum disorders, with rare variants on chromosome 1.33 showing transmission patterns in multiple affected families 4. Additionally, SAMD11 shows differential methylation patterns across breast cancer subtypes 5.