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A letter to the editor offering information on genetic screening of pachydermoperiostosis is presented.

Objective: To assess the presence of Chlamydia pneumoniae DNA in the joints of patients with reactive arthritis (ReA) and other arthritides., Methods: DNA was prepared from synovial tissue (ST) and several synovial fluid (SF) samples from 188 patients with either ReA, undifferentiated oligoarthritis, or other forms of arthritis, and from 24 normal (non-arthritis) individuals. Preparations were screened using polymerase chain reaction (PCR) assays that independently targeted the C. pneumoniae 16S ribosomal RNA and major outer membrane protein genes., Results: Twenty-seven of 212 ST samples (12.7%) were PCR positive for C. pneumoniae DNA; 10 SF samples from these 27 patients were similarly positive. Among the PCR-positive patients, 3 had ReA, 2 had Reiter's syndrome, 7 had undifferentiated oligoarthritis, 4 had undifferentiated monarthritis, 6 had rheumatoid arthritis, and 5 had other forms of arthritis. No samples from normal control individuals were PCR positive., Conclusion: DNA of C pneumoniae is present in synovial specimens from some arthritis patients. The prevalence of this organism in the joints was lower than that of C trachomatis, and synovial presence of the organism was not associated with any distinct clinical syndrome. Widely disseminated nucleic acids such as those of C. pneumoniae might have some role in the pathogenesis of several arthritides, since the organism was not found in the ST from normal control individuals.

Objective: To determine how HLA alleles are associated with the clinical disease patterns of patients with synovitis of recent onset., Methods: The HLA alleles A, B, C, DRbeta1, and DQbeta1 were determined in a cohort of 211 patients (mean age 42 years, 64% female, 79% white) with recent-onset synovitis in 1 or more peripheral joints. At a mean disease duration of 33 weeks, 98 patients (46%) met the American College of Rheumatology (ACR) criteria for rheumatoid arthritis (RA), 38 (18%) met the European Spondylarthropathy Study Group criteria for spondylarthropathy (SpA), and 75 (36%) were classified as having undifferentiated arthropathy (UA). Controls were racially matched healthy individuals (n = 244)., Results: Shared epitope (SE) alleles were significantly more common in rheumatoid factor-positive (RF+) patients fulfilling the ACR RA criteria than in other patients with early arthritis (65% versus 35%; P < 0.001). In addition, the RA patients had by far the highest frequency of radiographic erosions (52% and 39% in RF+ and RF- RA, respectively, versus 3% and 9% in SpA and UA patients, respectively; P < 0.0001). The presence of SE alleles was a particularly strong predictor of early erosions in the RF- RA patients (odds ratio [OR] 6.8, 95% confidence interval [95% CI] 1.2-45). The presence of 2 SE alleles or an associated DQbeta1*0301 (DQ7) or DQbeta1*0302 (DQ8) allele appeared to modestly increase the risk of early erosions, although these DQ alleles were in strong linkage disequilibrium with DRbeta1*0401, both in the patient and in the control populations. B27 was linked with the presence of SE alleles in the patients, including those patients fulfilling the RA criteria, but not in the controls (12% versus 3%; P < 0.001). Enthesitis was present in 23 (11%) of 211 patients, was highly associated with B27 (OR 4.2, 95% CI 1.5-11.5), and surprisingly, was not a feature specific only to the SpA group. The B8-DR3 haplotype was significantly increased in the patient subgroups compared with controls (17% versus 7%; P < 0.01), although the clinical significance of this association is unclear., Conclusion: This study of HLA associations in a diverse cohort of early synovitis patients emphasizes the complex degree of genetic interaction between alleles at several major histocompatibility complex loci, which regulates clinical phenotypes. In particular, SE and B27, while predisposing patients to characteristic clinical syndromes, had an unexpected degree of association in this cohort, perhaps explaining the overlap in clinical features in many patients.

Objective: The recent identification of antigens or nucleic acids of infectious agents in the joints of patients with reactive arthritis has raised questions about whether chlamydial or other infectious agent nucleic acids are also present in normal joints. We had the opportunity to study synovium from 30 asymptomatic volunteer subjects by use of polymerase chain reaction (PCR) for attempted identification of Chlamydia and other infectious agents., Methods: All subjects had blind needle synovial biopsies with the Parker-Pearson needle. DNA was extracted and PCR performed using primers for Chlamydia trachomatis, Chlamydia pneumoniae, Borrelia burgdorferi, and pan bacterial 16S ribosomal RNA (rRNA)., Results: Two subjects were identified with nucleic acid for the 16S rRNA gene of C trachomatis. All other PCR reactions were negative except for the pan bacterial 16S rRNA in the C trachomatis-positive subjects. Both subjects, although symptom free, had some evidence of synovial reaction., Conclusion: C trachomatis appears to occasionally be disseminated to joints without producing overt disease.