title: Decreased plasma concentrations of the C4B complement protein in autism.
abstract: OBJECTIVE
  To determine complement C4 protein concentrations in the plasmas of autistic subjects and their family members.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Center for Persons with Disabilities and the Department of Biology, Utah State University, Logan.
  
  
  METHODS
  Forty-two autistic subjects (34 males [81%] and eight females [19%]), 50 of their biologic parents, 21 siblings, and 105 normal subjects (56 females [53%] and 49 males [47%]; all white) living in northern Utah.
  
  
  METHODS
  None.
  
  
  METHODS
  The enzyme-linked immunosorbent assay was used to determine C4 protein concentrations in autistic subjects.
  
  
  RESULTS
  Plasma concentration (median, 14.7 g/L of the C4B protein) in autistic patients was significantly (P = .01) decreased compared with that of normal subjects (median, 22.4 g/L). The C4B concentrations in parents and siblings of autistic children were decreased, but not significantly. The C4A protein concentrations in the plasma of autistic subjects and their family members were normal.
  
  
  CONCLUSIONS
  Decreased protein concentrations of C4B may be associated with autism.
authors.affiliation: Center for Persons with Disabilities, Utah State University, Logan.
authors.forename: R P
authors.initials: RP
authors.lastname: Warren
authors.forename: R A
authors.initials: RA
authors.lastname: Burger
authors.forename: D
authors.initials: D
authors.lastname: Odell
authors.forename: A R
authors.initials: AR
authors.lastname: Torres
authors.forename: W L
authors.initials: WL
authors.lastname: Warren
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000911:Antibodies, Monoclonal; D001321:Autistic Disorder / Q000097:blood* / Q000175:diagnosis / Q000235:genetics; D015551:Autoimmunity; D002648:Child; D002675:Child, Preschool; D002896:Chromosomes, Human, Pair 6; D015934:Complement C4a / Q000737:chemistry* / Q000235:genetics; D015935:Complement C4b / Q000032:analysis* / Q000235:genetics; D005190:Family; D005260:Female; D005838:Genotype; D006684:HLA-DR Antigens; D006801:Humans; D008285:Major Histocompatibility Complex; D008297:Male; D011569:Psychiatric Status Rating Scales
chemical_list: D000911:Antibodies, Monoclonal; D006684:HLA-DR Antigens; D015934:Complement C4a; D015935:Complement C4b