KLHL11 (Kelch Like Family Member 11) is a component of a cullin-RING-based E3 ubiquitin-protein ligase complex (BTB-CUL3-RBX1) that mediates ubiquitination and proteasomal degradation of target proteins [UniProt]. Functionally, it operates as a substrate adapter within the Cul3-RING ubiquitin ligase complex, localizing to the cytoplasm and cytosol where it facilitates ubiquitin-dependent protein catabolism [GO Annotations]. Clinically, KLHL11 has emerged as a significant biomarker for autoimmune brainstem encephalitis. In a large cohort analysis, KLHL-11 antibodies were the most frequently detected neural autoantibodies, identified in 26 of 98 patients (27%) with autoimmune brainstem encephalitis 1. KLHL-11 associated autoimmune brainstem encephalitis exhibits characteristic neurological features including diplopia, ataxia, dysarthria, and vestibulocochlear dysfunction, with strong paraneoplastic associations—55 of 98 patients (56%) had concurrent cancer, predominantly germ cell tumors (23 patients) 1. The antibody has been recognized as an important diagnostic biomarker in the expanding landscape of neuronal antibodies in autoimmune movement disorders 2 and paraneoplastic neurologic disorders 3, providing diagnostic utility for this treatable autoimmune condition.