GPATCH11 variants cause mis-splicing and early-onset retinal dystrophy with neurological impairment

Spliceosome and ciliary dysfunctions can lead to remarkably similar clinical syndromes. Studying ten individuals with retinal dystrophy, neurological involvement, and skeletal abnormalities, suggestive of both spliceosomopathies and ciliopathies, we involved GPATCH11, a lesser-known GPATCH-domain-containing regulators of RNA metabolism. To elucidate GPATCH11 function, we employed fibroblasts from unaffected individuals and patients carrying a recurring mutation specifically removing the main part of the GPATCH-domain while preserving other domains. Additionally, we generated a mouse model replicating the patients genetic defect, exhibiting behavioural abnormalities and retinal dystrophy. Our findings revealed GPATCH11 unique subcellular localization, marked as foci staining pattern and a diffuse presence in the nucleoplasm, alongside its centrosomal localization, indicating roles in RNA and cilia metabolism. We show dysregulation of U4 snRNA in patient cells and dysregulation in both gene expression and spliceosome activity within the mutant mouse retina, impacting key processes such as photoreceptor light responses, RNA regulation, and primary cilia-associated metabolism. These results highlight GPATCH11 roles in RNA metabolism, spliceosome regulation, and potential ciliary involvement. They underscore its significance in maintaining proper gene expression, contributing to retinal, neurological, and skeletal functions. Our research also demonstrates how studying rare genetic disorders can reveal broader gene functions, providing insights into GPATCH11 multifaceted roles.