title: Routine molecular genotyping of HLA-B27 in spondyloarthropathies overcomes the obstacles of serological typing and reveals an increased B *2702 frequency in ankylosing spondylitis.
abstract: OBJECTIVE
  To evaluate the reproducibility and reliability of polymerase chain reaction (PCR) in HLA-B27 typing compared to the conventionally used microlymphocytotoxicity test (MLCT). To determine the HLA-B27 subtype frequencies (B*2701-B*2709) in patients with HLA-B27 associated disease and healthy persons using sequence specific oligonucleotides (SSO).
  
  
  METHODS
  398 consecutive patients were HLA-B27 typed by MLCT and PCR. Subtyping by SSO was performed in 142 patients with HLA-B27 associated disease [ankylosing spondylitis (AS) n = 38, reactive arthritis 44, undifferentiated spondyloarthropathy (uSpA) 45, psoriatic arthritis 15] and 125 healthy HLA-B27 controls.
  
  
  RESULTS
  MLCT identified 61 HLA-B27 positive patients (15.3%); PCR identified 78 positive patients (19.6%). MLCT gave false negative results for 8 patients (2.0%) and false positives for a further 7 (1.8%). Only subtypes B*2702 and B*2705 were present in patients and controls. Overall frequencies of B*2702 in patients and controls were 14.1 and 9.6%, respectively. The B*2702 frequency was significantly (pcorr. < 0.04) higher in AS (23.7%) and lower in uSpA (6.7%) patients.
  
  
  CONCLUSIONS
  HLA-B27 typing by PCR is reliable and reproducible and therefore recommended for routine typing. It overcomes the obstacles of serological typing, i.e., equivocal results and cross-reactivity. In addition, subtype frequencies (B*2702 and B*2705) are equally distributed among patients and controls, although subtype B*2702 seems to be more frequent in AS and less so in uSpA.
authors.affiliation: Rheumaeinheit, Medizinische Poliklinik, Klinikum Innenstadt, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Frankenberger
authors.forename: S
authors.initials: S
authors.lastname: Breitkopf
authors.forename: E
authors.initials: E
authors.lastname: Albert
authors.forename: S
authors.initials: S
authors.lastname: Scholz
authors.forename: E
authors.initials: E
authors.lastname: Keller
authors.forename: M
authors.initials: M
authors.lastname: Schattenkirchner
authors.forename: E H
authors.initials: EH
authors.lastname: Weiss
authors.forename: H
authors.initials: H
authors.lastname: Kellner
mesh_terms: D000595:Amino Acid Sequence; D003429:Cross Reactions; D005091:Exons / Q000276:immunology; D005188:False Negative Reactions; D005838:Genotype; D015796:HLA-B27 Antigen / Q000235:genetics*; D006650:Histocompatibility Testing; D006801:Humans; D010641:Phenotype; D016133:Polymerase Chain Reaction; D013166:Spondylitis / Q000235:genetics* / Q000276:immunology*
chemical_list: D015796:HLA-B27 Antigen