title: Clinical and genetic aspects of psoriatic arthritis "sine psoriasis".
abstract: OBJECTIVE
  To characterize the clinical pattern of psoriatic arthritis (PsA) sine psoriasis.
  
  
  METHODS
  Fifty-seven patients (31 men, 26 women, mean age 46.32 +/- 14.12 yrs) with undifferentiated spondyloarthropathy (SpA) were studied. Two subsets were defined: (1) 21 patients with familial psoriasis (12 men, 9 women, mean age 49.29 +/- 14.17 yrs); (2) 36 patients without familial psoriasis (19 men, 17 women, mean age 44.58 +/- 14.00 yrs). The prevalence of the following clinical variables was evaluated: low back pain, enthesopathy, dactylitis, distal interphalangeal (DIP) arthritis, spinal involvement, and discitis. In all patients the following HLA haplotypes were tested: B7, B13, B17, B18, B27, B38, Cw6, and DR7.
  
  
  RESULTS
  Dactylitis and DIP arthritis were markedly present in the articular subset with familial psoriasis (p < 0.0001) that also showed a high frequency rate of HLA-Cw6 (p < 0.0001 vs controls and patients without familial psoriasis). HLA-B27 was markedly frequent in patients without familial psoriasis (p < 0.0001 vs controls and p = 0.019 vs patients with familial psoriasis). In addition, in patients with familial psoriasis the log-linear model showed that the presence of HLA-Cw6 was related to the presence of DIP arthritis as well as dactylitis (likelihood ratio chi-square change of 5.891 and p = 0.015).
  
  
  CONCLUSIONS
  A subset of patients with PsA "sine psoriasis" is identified by the occurrence of a SpA with dactylitis and/or DIP arthritis, presence of HLA-Cw6, and familial psoriasis in first or second-degree relatives.
authors.affiliation: Department of Clinical and Experimental Medicine, University Federico II, via Sergio Pansini 5, 80131 Naples, Italy. rscarpa@unina.it
authors.forename: Raffaele
authors.initials: R
authors.lastname: Scarpa
authors.forename: Elena
authors.initials: E
authors.lastname: Cosentini
authors.forename: Francesco
authors.initials: F
authors.lastname: Manguso
authors.forename: Alfonso
authors.initials: A
authors.lastname: Oriente
authors.forename: Rosario
authors.initials: R
authors.lastname: Peluso
authors.forename: Mariangela
authors.initials: M
authors.lastname: Atteno
authors.forename: Fabio
authors.initials: F
authors.lastname: Ayala
authors.forename: Agesilao
authors.initials: A
authors.lastname: D'Arienzo
authors.forename: Pasquale
authors.initials: P
authors.lastname: Oriente
mesh_terms: D000328:Adult; D015535:Arthritis, Psoriatic / Q000150:complications / Q000235:genetics* / Q000473:pathology; D005190:Family; D005192:Family Health; D005260:Female; D005384:Finger Joint / Q000473:pathology; D020022:Genetic Predisposition to Disease; D015796:HLA-B27 Antigen / Q000235:genetics; D015236:HLA-C Antigens / Q000235:genetics; D006650:Histocompatibility Testing; D006801:Humans; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000150:complications / Q000235:genetics* / Q000473:pathology; D013717:Tenosynovitis / Q000150:complications / Q000235:genetics / Q000473:pathology
chemical_list: D015796:HLA-B27 Antigen; D015236:HLA-C Antigens; C528994:HLA-C*06 antigen