Clinical and Paraclinical Characterizations, Management, and Prognosis in DPPX Antibody-Associated Encephalitis: A Systematic Review.

In dipeptidyl-peptidase-like protein 6 (DPPX) antibody-associated encephalitis, DPPX antibodies from serum and CSF target the extracellular subunit of the voltage-gated potassium channel 4.2. This targeting leads to a characteristic clinical triad comprising gastrointestinal symptoms (predominantly diarrhea), cognitive-psychiatric dysfunction, and manifestations of CNS hyperexcitability, with hyperekplexia being a more specific feature. This rare disease typically presents with a subacute or chronic course and often affects middle-aged and older individuals. Patients may have a weak association with certain hematologic malignancies, particularly lymphoma and chronic lymphocytic leukemia. Brain MRI typically shows normal findings or nonspecific white matter changes. DPPX antibody-associated encephalitis responds well to immunotherapy, and most patients ultimately present with a good prognosis. However, relapses can occur. To improve our understanding of this rare but treatable autoimmune encephalitis and avoid misdiagnosis, we conduct a systematic review and summarize the current knowledge of its clinical and paraclinical features, management, and prognosis.