title: HLA-C and TNF gene polymorphisms are associated with psoriasis in Brazilian patients.
abstract: BACKGROUND
  Polymorphisms at the human leukocyte antigens (HLA-C) and tumor necrosis factor (TNF) genes have been associated with susceptibility to psoriasis in several worldwide populations. In this study, HLA-C and TNF (-238/-308) polymorphisms were performed in 125 Brazilian patients and 202 healthy controls.
  
  
  METHODS
  HLA-C and TNF promoter region alleles were typed by polymerase chain reaction using sequence-specific primer-polymerase chain reaction.
  
  
  RESULTS
  The presence of HLA-C*06 was associated with psoriasis onset, particularly in younger patients, being more frequent for patients with disease onset before the age of 20 years (P = 0.03), 25 years (P = 0.01), or 30 years (P = 0.03). No association between HLA-C*06 and psoriasis was observed for patients older than 35 years. Susceptibility to psoriatic arthritis was associated with the TNF -238 G/A genotype (P = 0.02). The TNF -308A allele was overrepresented in patients (P = 0.0061), and the TNF -308 G/A genotype was increased in generalized forms (erythrodermic and generalized pustular psoriasis) compared to plaque psoriasis (P < 0.001). The TNF -238A/HLA-C*06 haplotype was overrepresented in patients (P = 0.025), while the TNF -238G/HLA-C*15 haplotype was increased in controls (P = 0.037).
  
  
  CONCLUSIONS
  The strong association of HLA-C*06 allele with disease susceptibility, particularly in early onset psoriasis, indicates that younger ages could be considered to stratify psoriasis into early and late types. TNF -308 polymorphisms can be associated with psoriasis susceptibility and severity. Potential genetic markers of psoriasis in populations with a complex mixture of ethnicities should be investigated.
authors.affiliation: Division of Dermatology, Internal Medicine Department, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Renata N
authors.initials: RN
authors.lastname: Cardili
authors.affiliation: Division of Immunology, Internal Medicine Department, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Neifi S
authors.initials: NS
authors.lastname: Deghaide
authors.affiliation: Chemistry Department, School of Philosophy, Sciences and Letters of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Celso T
authors.identifier: http://orcid.org/0000-0002-7337-1203
authors.initials: CT
authors.lastname: Mendes-Junior
authors.affiliation: Division of Immunology, Internal Medicine Department, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Eduardo A
authors.initials: EA
authors.lastname: Donadi
authors.affiliation: Division of Dermatology, Internal Medicine Department, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, Brazil.
authors.forename: Cacilda S
authors.initials: CS
authors.lastname: Souza
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000483:Alleles; D000704:Analysis of Variance; D001938:Brazil / Q000453:epidemiology; D016022:Case-Control Studies; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000453:epidemiology*; D015236:HLA-C Antigens / Q000235:genetics*; D006785:Hospitals, University; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D016133:Polymerase Chain Reaction / Q000379:methods; D011110:Polymorphism, Genetic; D011379:Prognosis; D011401:Promoter Regions, Genetic; D011565:Psoriasis / Q000453:epidemiology* / Q000235:genetics* / Q000473:pathology; D012189:Retrospective Studies; D018570:Risk Assessment; D017678:Sex Distribution; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*; D055815:Young Adult
chemical_list: D015236:HLA-C Antigens; C439524:TNF protein, human; D014409:Tumor Necrosis Factor-alpha