title: Clinical utility of seropositive voltage-gated potassium channel-complex antibody.
abstract: BACKGROUND
  Antibodies against voltage-gated potassium channel (VGKC)-complex are implicated in the pathogenesis of acquired neuromyotonia, limbic encephalitis, faciobrachial dystonic seizure, and Morvan syndrome. Outside these entities, the clinical value of VGKC-complex antibodies remains unclear.
  
  
  METHODS
  We conducted a single-center review of patients positive for VGKC-complex antibodies over an 8-year period.
  
  
  RESULTS
  Among 114 patients positive for VGKC-complex antibody, 11 (9.6%) carrying the diagnosis of limbic encephalitis (n = 9) or neuromyotonia (n = 2) constituted the classic group, and the remaining 103 cases of various neurologic and non-neurologic disorders comprised the nonclassic group. The median titer for the classic group was higher than the nonclassic group (p< 0.0001). A total of 90.9% of the patients in the classic and 21.4% in the nonclassic group possessed high (>0.25 nM) VGKC-complex antibody levels (p< 0.0001). A total of 75.0% of the patients in the high-level group had definite or probable autoimmune basis, while nonautoimmune disorders were seen in 75.6% of patients from the low-level group (p< 0.0001). A total of 26.3% of patients were found with active or remote solid organ or hematologic malignancy, but no antibody titer difference was observed among subgroups of absent, active, or remote malignancy. Compared to age-matched US national census, rates of active cancer in our cohort were higher in patients older than 45 years.
  
  
  CONCLUSIONS
  High VGKC-complex antibody titers are more likely found in patients with classically associated syndromes and other autoimmune conditions. Low-level VGKC-complex antibodies can be detected in nonspecific and mostly nonautoimmune disorders. The presence of VGKC-complex antibody, rather than its level, may serve as a marker of malignancy.
authors.affiliation: Neurohospitalist Program (AJ), Aultman Hospital, Canton; and Department of Neurology (LS, KM, AR-G, YL) and Department of Quantitative Health Sciences, Lerner Research Institute (JL), Cleveland Clinic Foundation, OH.
authors.forename: Adham
authors.initials: A
authors.lastname: Jammoul
authors.affiliation: Neurohospitalist Program (AJ), Aultman Hospital, Canton; and Department of Neurology (LS, KM, AR-G, YL) and Department of Quantitative Health Sciences, Lerner Research Institute (JL), Cleveland Clinic Foundation, OH.
authors.forename: Luay
authors.initials: L
authors.lastname: Shayya
authors.affiliation: Neurohospitalist Program (AJ), Aultman Hospital, Canton; and Department of Neurology (LS, KM, AR-G, YL) and Department of Quantitative Health Sciences, Lerner Research Institute (JL), Cleveland Clinic Foundation, OH.
authors.forename: Karin
authors.initials: K
authors.lastname: Mente
authors.affiliation: Neurohospitalist Program (AJ), Aultman Hospital, Canton; and Department of Neurology (LS, KM, AR-G, YL) and Department of Quantitative Health Sciences, Lerner Research Institute (JL), Cleveland Clinic Foundation, OH.
authors.forename: Jianbo
authors.initials: J
authors.lastname: Li
authors.affiliation: Neurohospitalist Program (AJ), Aultman Hospital, Canton; and Department of Neurology (LS, KM, AR-G, YL) and Department of Quantitative Health Sciences, Lerner Research Institute (JL), Cleveland Clinic Foundation, OH.
authors.forename: Alexander
authors.initials: A
authors.lastname: Rae-Grant
authors.affiliation: Neurohospitalist Program (AJ), Aultman Hospital, Canton; and Department of Neurology (LS, KM, AR-G, YL) and Department of Quantitative Health Sciences, Lerner Research Institute (JL), Cleveland Clinic Foundation, OH.
authors.forename: Yuebing
authors.initials: Y
authors.lastname: Li