title: Haplotype associations of the major histocompatibility complex with psoriasis in Northeastern Thais.
abstract: BACKGROUND
  To evaluate the distributions of the human leukocyte antigen (HLA) at class I and II loci that may contribute to the genetic susceptibility to psoriasis patients in the north-eastern Thai population.
  
  
  METHODS
  We analyzed the allelic frequencies of HLA class I and II by using the polymerase chain reaction-amplification refractory mutation system (PCR-ARMS) technique and polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP), respectively, in 140 north-eastern Thais with psoriasis that were sudivided into two groups: one with age at onset < 40 years (type I psoriasis; 95 cases) and the other with age at onset > 40 years (type II psoriasis; 45 cases). Three hundred healthy unrelated north-eastern Thais were used as controls.
  
  
  RESULTS
  HLA-A*01, -A*0207, -A*30, -B*08, -B*13, -B*4601, -B*57, -Cw*01, -Cw*0602, and -DRB1*07 were positively associated with type I psoriasis, whereas HLA-A*24, -A*33, and -Cw*04 were negatively associated with type I psoriasis with statistical significance when compared to the controls. The Cw*0602 allele showed the strongest correlation with this type. In addition, the frequencies of HLA-A*0207, -A*30, -Cw*01, and -DRB1*1401 were significantly increased in type II psoriasis. HLA-A*207, -B*4601, -Cw*01, -DRB1*09, -DQB1*0303 (AH46.1), HLA-A*01-B*57-Cw*0602-DRB1*07-DQB1*0303 (AH57.1), and HLA-A*30, -B*13, -Cw*0602, -DRB1*07, and -DQB1*02 (AH13.1) were identified as high-risk major histocompatibility complex (MHC) halotypes for psoriasis patients in the early onset group in north-eastern Thais.
  
  
  CONCLUSIONS
  This study demonstrates not only the differential association between HLA markers and types of psoriasis according to age at onset, but also a newly found high-risk and a protective haplotype in Thai psoriasis patients.
authors.affiliation: Division of Dermatology, Department of Medicine, Faculty of Medicine, and Blood Transfusion Center, Khon Kaen University, Khon Kaen 40002, Thailand. c_choonhakarn_dematologist@hotmail.com
authors.forename: Charoen
authors.initials: C
authors.lastname: Choonhakarn
authors.forename: Amornrat
authors.initials: A
authors.lastname: Romphruk
authors.forename: Chintana
authors.initials: C
authors.lastname: Puapairoj
authors.forename: Kunya
authors.initials: K
authors.lastname: Jirarattanapochai
authors.forename: Arunrat
authors.initials: A
authors.lastname: Romphruk
authors.forename: Chanvit
authors.initials: C
authors.lastname: Leelayuwat
mesh_terms: D000328:Adult; D017668:Age of Onset; D005787:Gene Frequency / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006239:Haplotypes / Q000235:genetics*; D015395:Histocompatibility Antigens Class I / Q000235:genetics*; D000949:Histocompatibility Antigens Class II / Q000235:genetics*; D006801:Humans; D019901:Locus Control Region / Q000235:genetics; D016017:Odds Ratio; D011565:Psoriasis / Q000235:genetics*; D013785:Thailand
chemical_list: D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II