Diagnostic performance and predictive value of rheumatoid factor, anti-cyclic-citrullinated peptide antibodies and HLA-DRB1 locus genes in rheumatoid arthritis

Table 2 Frequencies of HLA-DRB1 alleles in patients and control

HLA-DRB1 allele	Patients	Control	P value
HLA-DRB1-01	27(45%)	5(5%)	0.001
HLA-DRB1-02	11(18%)	0(0%)	0.05
HLA-DRB1-03	10(16%)	50(50%)	0.03
HLA-DRB1-04*	21(35%)	10(10%)	0.05
- HLA-DRB1-0401	3(15%)	3(13%)
- HLA-DRB1-0404	1(5%)	9(9%)
- HLA-DRB1-0405	17(80%)	77(77%)
DRB104* non-SE alleles	0 (0%)	1(1%)
HLA-DRB1-07	4(6%)	25(25%)	0.02
HLA-DRB1-08	6(10%)	5(5%)	NS
HLA-DRB-09	1(1.7%)	1(1%)	NS
HLA-DRB1-10	0(0%)	15(15%)	0.002
HLA-DRB1-11	5(8.3%)	20(20%)	NS
HLA-DRB-12	10(16%)	16(16%)	NS
HLA-DRB-13	16(26.7%)	30(30%)	NS
HLA-DRB-14	1(1.7%)	4(4%)	NS
HLA-DRB1-15	0(0%)	16(16%)	0.002

Values are expressed as n (%). HLA: human leukocyte antigen. *According to HLA-DRB1*04 subtyping the shared epitopes encoding alleles *0409, *0413, *0416 and *0421 were classified as *0401 alleles, *0408, *0410 and *0419 were classified as *0404. The DRB1*0405 alleles were analyzed as a separate entity. All other DRB1*04 alleles were classified as DRB1*04 non-SE alleles.⁽⁴⁾