The aim of this study was to investigate the contribution of the different B27 subtypes to ankylosing spondylitis (AS) susceptibility. The polymerase chain reaction (PCR) in combination with the sequence-specific oligonucleotide probes (SSOs) was used to analyse the polymorphism in exon 2 and 3 of HLA-B27 in two Asian groups with different genetic HLA structures: Indian (I) and Thai (T) populations. The same number of AS patients (45) and healthy B27 positive donors (n = 17) from both populations were analysed in order to ascertain the B27 subtypes. Three different findings can be concluded from this study: 1) B*2707 has been found to be associated with AS in both populations. This association has not been previously reported in either ethnic group. 2) B*2704 is strongly associated with AS in the Thai patients (91% in AS vs. 47% in C; RR = 11.5; EF = 0.83). In contrast, B*2704 was found with similar frequency in Asian Indians AS patients and controls (41% in AS vs. 41% in C.). 3) B*2706 was found overrepresented in control populations and absent in AS patients (0% in AS vs. 47% in C.; pc < 10(-6)) showing the maximum value of protective fraction (PF = 1). The B*2706 negative association with AS has not been previously described in other ethnic groups and could indicate a protective effect of this subtype on AS susceptibility. The B*2706 allele has two changes relative to B*2704 at residue 114 (His to Asp) and 116 (Asp to Tyr) in the pockets D/E. The importance that these differences can play in the pathogenesis of AS are discussed.

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Histocompatibility antigen (HLA) A and B typing on lymphocytes from 87 unrelated Thai children who had been hospitalized with dengue shock syndrome (DSS) and/or dengue hemorrhagic fever (DHF) was compared with that found in 138 controls who had not been hospitalized with clinical dengue infection. These data are presented as descriptive information; however, a statistical analysis was performed to identify potentially important relationships for future study. Several deviations (P less than 0.05) were detected in the distribution of four HLA-A and three HLA-B antigens. The prevalence of one HLA-A antigen and two HLA-B antigens appeared to relate to the development of DSS, with a positive association seen for HLA-A2 and HLA-B blank and a negative relationship for HLA-B13. These findings require confirmation, but they do suggest that genetic susceptibility may be important in the development of DHF/DSS and indicate that further broader studies of genetic markers might be rewarding.

Diffuse systemic sclerosis and the related syndromes were diagnosed in 115 patients during 1977-1987. Sixty-nine patients were available for clinical evaluation and analysis. These included 46 patients with diffuse systemic sclerosis, 2 with limited cutaneous systemic sclerosis, 2 with linear scleroderma, 18 with overlap syndrome (OS), and one with primary Raynaud's disease. The major clinical manifestations among the diffuse scleroderma patients were the involvement of the following systems; cutaneous (93.3%), musculoskeletal (69.6%), gastrointestinal (54.3%), and pulmonary (43.3%) while renal involvement (4.3%) was less common. Antinuclear antibodies were found in 89.7% with predominating speckle pattern (86.2%) and anti Scl 70 antibody (40.6%). In contrast to the Western series, HLA-DR2 was significantly increased in our diffuse systemic sclerosis patients (p less than 0.01). Among the 18 OS patients, the involvement of pulmonary system (44.4%) was the major cause of morbidity and renal involvement (55.6%) was found frequently although it was clinically mild. In conclusion, our diffuse systemic sclerosis and related diseases patients seem to have milder clinical manifestations than those of the Western series.

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