title: [The molecular basis of HLA DR4 alleles associated with rheumatoid arthritis in a Chinese population].
abstract: HLA-DR4 gene was studied by polymerase chain reaction method in 95 patients with rheumatoid arthritis(RA) and 130 normal controls in a Shanghai population. The results showed that the DR4 was significantly associated with RA(RR = 3.1, chi 2 = 13.8, P < 0.005). The second exon of DR4 gene was also analysed by PCR-RFLP technique. There were at lest eight DR4 subtypes in this Chinese population. The DRB1 *0405 (Dw15) was the most common allele, accounting for 48% of DR4 positive normal individuals and also is a principal subtype associated with RA susceptibility (RR = 3.1, P < 0.005). Analysis of the third hyperpolymorphic region of DR4 positive samples showed that 92% of patients had a sequence encoding amino acids RRAA or KRAA compared with 56% of the  DR4 positive controls (chi 2 = 10.29 P < 0.005). All subtypes that were positively associated with RA susceptibility had the RRAA (DRB1* 0404, 0405. 0408 and 0410) or KRAA (DRB1 * 0401) sequences, while the negatively associated ones (DRB1 0402, 0403 and 0406) had not. As a further evidence, it strongly supported the "shared epitope" hypothesis. The different DR4 subtype structures and frequencies may account for the different associations of DR4 with RA in various ethnic groups.
authors.affiliation: Department of Biochemistry, Shanghai Second Medical University.
authors.forename: N S
authors.initials: NS
authors.lastname: Zhu
authors.forename: Y X
authors.initials: YX
authors.lastname: Wang
authors.forename: F Q
authors.initials: FQ
authors.lastname: Wang
mesh_terms: D000483:Alleles; D001172:Arthritis, Rheumatoid / Q000235:genetics*; D044466:Asian People; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D004198:Disease Susceptibility; D005802:Genes, MHC Class II; D015804:HLA-DR4 Antigen / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction
chemical_list: D015804:HLA-DR4 Antigen; D004247:DNA