Scientists have identified mutations in CD99L2, a gene previously associated only with immune function, as a cause of rare neurological movement disorders. Researchers analyzing genetic data from nearly 3,000 patients with coordination and muscle control problems discovered this unexpected genetic mechanism.

The finding emerged from large-scale genetic screening that connected CD99L2 disruptions to impaired nerve-cell communication. The gene, which scientists thought functioned exclusively in the immune system, actually maintains critical functions in neuronal signaling pathways. Mutations in CD99L2 disrupt the molecular processes that allow neurons to communicate effectively, leading to movement disorders characterized by poor coordination and weakened muscle control.

This discovery shifts understanding of how the immune system gene functions across different tissue types. The researchers demonstrated that CD99L2 operates in nervous system cells in ways distinct from its immune roles. Without proper CD99L2 function, neurons struggle to transmit signals at the synapses where they connect.

The study expands the genetic landscape of rare movement disorders. Previously, clinicians attributed many unexplained coordination problems to known genes or assumed they resulted from environmental causes. This work reveals that some patients carrying CD99L2 mutations had been undiagnosed or misdiagnosed for years.

The research carries immediate clinical implications. Patients with movement disorders of unknown origin can now be tested for CD99L2 mutations, potentially ending diagnostic odysseys that typically span years. Genetic counseling and family screening become possible once a clear genetic cause emerges.

The findings also open new research directions. Understanding how CD99L2 maintains neuronal communication could lead to therapies targeting the molecular pathways affected by these mutations. Scientists can now investigate whether similar dual-function genes control other systems, functioning differently in immune and neural tissue.

The study involved multiple research institutions collaborating to sequence and analyze patient genomes systematically. By examining nearly