Undifferentiated spondyloarthropathies in Brazilians: importance of HLA-B27 and the B7-CREG alleles in characterization and disease progression.
OBJECTIVE
To analyze the profile of the HLA-B27 and B7 cross-reactive group (CREG) alleles and the role of these markers in disease characterization and progression in patients with undifferentiated spondyloarthropathies (uSpA).


METHODS
A total of 80 patients with a diagnosis of uSpA (40 HLA-B27 positive and 40 HLA-B27 negative) were prospectively studied for 2 years. The control group consisted of 66 HLA-B27 positive and 112 HLA-B27 negative individuals without a history of seronegative SpA. HLA-B alleles were typed at low (B7-CREG alleles, i.e., B*7, B*54, B*55, B*56, B*40, B*42) or high resolution (B*27 alleles) using polymerase chain reaction-amplified DNA hybridized with sequence-specific oligonucleotide probes.


RESULTS
HLA-B*2705 was the most frequent allele, observed in 92.5% of the patients and in 77% of the controls, followed by the HLA-B*2702, observed in 5% of the patients and in 12% of the controls. HLA-B*2704 was observed in only one patient (2.5%), and was absent in the control population. HLA-B*2703 (6%) and HLA-B*2707 (5%) alleles were observed only in controls. No associations between HLA-B*27 alleles or B7-CREG alleles and any specific manifestation of uSpA were observed. HLA-B27 positive patients more frequently presented juvenile onset SpA (p = 0.002) and progression to ankylosing spondylitis (AS) (p = 0.03) than did HLA-B27 negative patients. The B7-CREG alleles were observed in 5% of the HLA-B27 positive uSpA group, in 25% of the HLA-B27 negative uSpA group, in 7% of the HLA-B27 positive controls, and in 13% of the HLA-B27 negative controls; a significant association was observed between the presence of the B7-CREG and the HLA-B27 negative uSpA group (p = 0.012).


CONCLUSIONS
The frequency of the HLA-B*2705 allele among the B27 positive uSpA patients of this series was closely similar to that reported for patients with ankylosing spondylitis (AS). The presence of HLA-B*27 alleles was associated with the progression to AS, and the presence of B7-CREG was associated with uSpA in the HLA-B27 negative group.
Sampaio-Barros
Percival D
PD
Rheumatology Unit, Department of Internal Medicine, State University of Campinas, Barao Geraldo, Campinas SP, CEP 13081-970, Brazil. psbarros@fcm.unicamp.br
Conde
Roseneide A
RA
Donadi
Eduardo A
EA
Kraemer
Maria Helena S
MH
Persoli
Ligia
L
Coimbra
Ibsen B
IB
Costallat
Lilian Teresa L
LT
Samara
Adil M
AM
Bértolo
Manoel B
MB
D000293:Adolescent; D000483:Alleles; D001938:Brazil / Q000453:epidemiology; D002648:Child; D018450:Disease Progression; D005260:Female; D020022:Genetic Predisposition to Disease; D015796:HLA-B27 Antigen / Q000235:genetics*; D015793:HLA-B7 Antigen / Q000235:genetics*; D006801:Humans; D007223:Infant; D007596:Joints / Q000473:pathology; D008297:Male; D010045:Outpatients; D011446:Prospective Studies; D013166:Spondylitis / Q000453:epidemiology / Q000235:genetics* / Q000473:pathology
D015796:HLA-B27 Antigen; D015793:HLA-B7 Antigen