title: Effects of age and sex on aquaporin-4 autoimmunity.
abstract: OBJECTIVE
  To determine the sex and age distribution of aquaporin-4 (AQP4) autoimmunity using data derived from clinical service laboratory testing of 56,464 patient samples.
  
  
  METHODS
  Observational analysis.
  
  
  METHODS
  Mayo Clinic Neuroimmunology Laboratory.
  
  
  METHODS
  Between October 1, 2005, and January 4, 2011, 56,464 patients were tested for AQP4-IgG; 2960 (5.2%) patients were seropositive.
  
  
  METHODS
  Seropositivity for AQP4-IgG.
  
  
  RESULTS
  Patients seropositive for AQP4-IgG were older than seronegative patients (mean [SD] age, 46 [16] vs 42 [15] years, respectively; P < .001). More females than males were tested (37,662 vs 16,810, respectively; P < .001). Among 2743 seropositive patients, 146 (5.3%) were pediatric (aged ≤18 years) and 333 (12.1%) were elderly (aged ≥65 years). The sex distribution of seropositive patients was 2465 females and 306 males (absolute female:male ratio, 8.1:1; P < .001). After adjusting for the number of females tested, an excess of females persisted (adjusted female:male ratio, 3.6:1). Female predominance for AQP4-IgG was more striking in adults (absolute female:male ratio, 8.4:1; adjusted female:male ratio, 3.5:1) than in pediatric patients (absolute female:male ratio, 4.3:1; adjusted female:male ratio, 2.9:1) (P < .001). Elderly women were more likely to be seropositive than individuals in other age categories (13.1% vs 6.0%, respectively; P < .001). The proportion of AQP4-IgG-seropositive individuals (detection rate), defined by decade of age, increased exponentially in women after age 50 years.
  
  
  CONCLUSIONS
  Seropositivity for AQP4-IgG occurs predominantly in females, particularly in individuals older than 18 years. Among seropositive patients, 1 in 6 is in the extremes of age. The detection rate of AQP4-IgG increased in women after age 50 years.
authors.affiliation: Department of Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
authors.forename: Amy M L
authors.initials: AM
authors.lastname: Quek
authors.forename: Andrew
authors.initials: A
authors.lastname: McKeon
authors.forename: Vanda A
authors.initials: VA
authors.lastname: Lennon
authors.forename: Jayawant N
authors.initials: JN
authors.lastname: Mandrekar
authors.forename: Raffaele
authors.initials: R
authors.lastname: Iorio
authors.forename: Yujuan
authors.initials: Y
authors.lastname: Jiao
authors.forename: Chiara
authors.initials: C
authors.lastname: Costanzi
authors.forename: Brian G
authors.initials: BG
authors.lastname: Weinshenker
authors.forename: Dean M
authors.initials: DM
authors.lastname: Wingerchuk
authors.forename: Claudia F
authors.initials: CF
authors.lastname: Lucchinetti
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Shuster
authors.forename: Sean J
authors.initials: SJ
authors.lastname: Pittock
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D051401:Aquaporin 4 / Q000276:immunology*; D001323:Autoantibodies / Q000096:biosynthesis*; D001327:Autoimmune Diseases / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000096:biosynthesis*; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D055815:Young Adult
chemical_list: C496030:AQP4 protein, human; D051401:Aquaporin 4; D001323:Autoantibodies; D007074:Immunoglobulin G