The syntheses of 1,2-dideoxy-D-ribofuranose and 1,2-dideoxy-1-phenyl-beta-D-ribofuranose are described. Oligodeoxynucleotides containing these analogues have been synthesised and hybridized to their complementary strands. Hypochromicity studies have shown that these duplices are less stable than either the totally complementary duplex or those containing A.C and G.T mismatches.

Certain class II determinants of the human histocompatibility locus antigens (HLA) have been implicated in the aetiology of several autoimmune diseases, including rheumatoid arthritis (RA) and insulin-dependent diabetes mellitus (IDDM). HLA-Dw4 was the first HLA determinant found to be significantly increased in RA patients compared with controls, while Dw4 and Dw3 were found to be significantly increased in IDDM patients. When the HLA-DR system was defined, RA patients were found to have an increased frequency of DR4 and IDDM patients an increased incidence of both DR4 and DR3 compared with controls. As the HLA-Dw specificities are narrower than the serologically defined DR specificities, it was of specific interest to the present study that Dw4, Dw10, Dw13, Dw14, Dw15 and DKT2 are included in DR4. We describe here new restriction fragment length polymorphisms (RFLPs) and, together with the newly described serologically defined DQ specificity TA10, test their prevalence and associations in controls and diseased patients. We find that the newly characterized DNA bands are present at a much higher frequency in RA and IDDM patients than in controls. These findings may lead to a greater understanding of the pathogenesis of such diseases.

We have used the XI Histocompatibility Workshop sequence-specific oligonucleotide probes to determine the DRB1, DQA1 and DQB1 genotypes by dot-blot hybridization of polymerase chain reaction (pcr)-amplified material from a homogenous black population in Zimbabwe. The DR4 subtype DRB1*0405, the DR3 subtype DRB1*0301, DQB1*0201 and DQB1*0302 and DQA1*0301 and DQA1*0501 were significantly increased in the IDDM group compared to the controls, whereas DRB1*11, DQB1*0602 and DQA1*0102 were significantly decreased. Taken together, the data show that susceptibility and resistance to IDDM are associated both with particular haplotypes and DQA1-DQB1 heterodimers without one or other being overriding.