Referenced in: none

Automatically associated channels: Kv1.4 , Kv3.1 , Kv4.2

Title: DPPX potassium channel antibody: frequency, clinical accompaniments, and outcomes in 20 patients.

Authors: William Oliver Tobin, Vanda A Lennon, Lars Komorowski, Christian Probst, Stacey Lynn Clardy, Allen J Aksamit, Juan Pablo Appendino, Claudia F Lucchinetti, Joseph Y Matsumoto, Sean J Pittock, Paola Sandroni, Maja Tippmann-Peikert, Elaine C Wirrell, Andrew McKeon

Journal, date & volume: Neurology, 2014 Nov 11 , 83, 1797-803

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/25320100

Abstract
To describe the detection frequency and clinical associations of immunoglobulin G (IgG) targeting dipeptidyl-peptidase-like protein-6 (DPPX), a regulatory subunit of neuronal Kv4.2 potassium channels.Specimens from 20 patients evaluated on a service basis by tissue-based immunofluorescence yielded a synaptic immunostaining pattern consistent with DPPX-IgG (serum, 20; CSF, all 7 available). Transfected HEK293 cell-based assay confirmed DPPX specificity in all specimens. Sixty-nine patients with stiff-person syndrome and related disorders were also evaluated by DPPX-IgG cell-based assay.Of 20 seropositive patients, 12 were men; median symptom onset age was 53 years (range, 13-75). Symptom onset was insidious in 15 and subacute in 5. Twelve patients reported prodromal weight loss. Neurologic disorders were multifocal. All had one or more brain or brainstem manifestations: amnesia (16), delirium (8), psychosis (4), depression (4), seizures (2), and brainstem disorders (15; eye movement disturbances [8], ataxia [7], dysphagia [6], dysarthria [4], respiratory failure [3]). Nine patients reported sleep disturbance. Manifestations of central hyperexcitability included myoclonus (8), exaggerated startle (6), diffuse rigidity (6), and hyperreflexia (6). Dysautonomia involved the gastrointestinal tract (9; diarrhea [6], gastroparesis, and constipation [3]), bladder (7), cardiac conduction system (3), and thermoregulation (1). Two patients had B-cell neoplasms: gastrointestinal lymphoma (1), and chronic lymphocytic leukemia (1). Substantial neurologic improvements followed immunotherapy in 7 of 11 patients with available treatment data. DPPX-IgG was not detected in any of the stiff-person syndrome patients.DPPX-IgG is a biomarker for an immunotherapy-responsive multifocal neurologic disorder of the central and autonomic nervous systems.