MAPK8 and syndromic X-linked intellectual disability Najm type: Our study uniquely identifies the JNK-ROS signaling axis as a critical mediator of CG cell apoptosis in CASK-deficient mice, advancing the field by providing the first In Vivo evidence that targeted inhibition of JNK signaling can alleviate both structural and functional cerebellar deficits in a genetically relevant model of MICPCH syndrome.