1.Ayoub AA and 2 Yousree ZA.
Departments of 1Microbiology and 2Internal Medicine. Faculty of Medicine for Girls Al Azhar University.
Inheritance
of specific HLA-DRB1 alleles or their corresponding haplotypes were reported to
predispose to rheumatoid arthritis (RA). An increased frequency of either of
HLA-DR4, DR1or DR10 alleles was confirmed in different ethnic populations.
These alleles share certain conserved amino acid sequence (shared epitope) that
may influence RA susceptibility rather than the entire allele. In this study,
HLA-DRB1 allele distribution among 21 RA Egyptian patients and 20 healthy
controls was investigated. Characterization of HLA-DR alleles was done by
oligotyping using polymerase chain reaction allele specific amplification
followed by reverse hybridization of specific polymorphic sequences. The most
frequent DRB1- alleles were DRB1*04 (42.9%) and *10 (33.3%), and DRB1*04 (65.0%), *01 (35.0%) and *11 (30%)
among controls. HLA-DRB1*01 and *03 were more frequently found in controls
compared to patients (35.0% vs 9.5%, P < 0.05 and 20.0% vs 4.8%, P < 0.05 respectively), implying a possible role for
these two alleles in protection (or resistance) to RA. HLA-DRB1*14 and *16 were
only detected in patients but lacked an association to RA susceptibility while
HLA-DRB1*05, *06, *08, *09 and*12 were not detected neither in patients nor in
controls. Alleles encoding for the SE were detected in 52.4% of RA patients and
45.0% of controls, the difference in the frequency of detection was
nonsignificant. In conclusion, the role of HLA-DRB1 alleles (and the effect of
the SE) in genetic susceptibility to RA is not confirmed while a trend for a
protective role for HLA-DRB1 *01 and*03 is shown. Further investigation in an
inception cohort of big number of patients from different areas in Egypt is
recommended.