Generation and ophthalmological characterization of oculocutaneous albinism type 1 pig models by selection-free genome editing

Oculocutaneous albinism type 1 (OCA1) is an autosomal recessive disorder caused by mutations in the tyrosinase (TYR) gene, resulting in melanin deficiency and severe visual impairments. Although mouse models provide insights into OCA1 pathogenesis, they exhibit significant anatomical and physiological differences from humans, particularly in ocular structure and function, thereby limiting their ability to recapitulate human OCA1 phenotypes. Therefore, in this study, we generated a porcine OCA1 model by selection-free genome editing via somatic cell nuclear transfer to characterize ophthalmological features and evaluate their translational relevance to human OCA1. Our approach utilized TYR-targeting CRISPR/Cas9 ribonucleoproteins without the need for single-cell-derived clonal expansion, thus streamlining the generation process. After somatic cell nuclear transfer with TYR knockout donor cells, the embryos demonstrated normal in vitro embryonic development comparable to the control, resulting in four healthy OCA1 piglets that exhibited characteristic OCA1 phenotypes with complete melanin loss in ocular and cutaneous tissues. Comprehensive ophthalmological analyses revealed significant structural abnormalities, including marked reduction in retinal layer thickness and elevated intraocular pressure. Remarkably, electroretinography revealed selective impairment of the rod bipolar pathway with reduced b-wave amplitudes and increased oscillatory potentials, indicating disturbances in synaptic processing. Overall, our study demonstrates the efficiency and reliability of selection-free genome editing for generating porcine OCA1 models. Moreover, the ophthalmological findings provide valuable insights for exploring retinal dysfunction and pigmentation mechanisms and advancing the preclinical evaluation of potential therapeutic interventions for human OCA1.