The clinical manifestations of 131 rheumatic disease patients with anti-Sm antibody were studied. A variety of standard tests was utilized in the study, namely, the FANA test with mouse kidney as substrate for the assay of ANA, the Crithidia test for anti-double stranded DNA (anti-dsDNA) and double immunodiffusion for detecting antibodies to extractable nuclear antigens. The patients were grouped according to the presence of anti-Sm alone, or anti-Sm with some other antibodies. There were 17 with anti-Sm alone; 55 with anti-Sm+anti-RNP; 15 with anti-Sm+anti-dsDNA; and 44 with anti-Sm+anti-RNP. The result of our study showed that although anti-Sm could be found in other diseases, it was exclusively detected in SLE only if anti-dsDNA was also present. Further, the SLE patients with anti-Sm alone had more frequent central nervous system manifestations than other groups of patients. The renal manifestation was observed more frequently in the group of SLE patients with anti-Sm+anti-dsDNA (92.9%). Among other major manifestations, haematologic involvement had a tendency to be less common in the group of patients with anti-Sm alone. The study concludes that the presence of anti-Sm antibody may be of some value to predict the clinical outcome.

To assess whether the CYP2C19 polymorphism modified the effect of cyclophosphamide on ovarian toxicity in Thai patients with SLE. We performed a case-control study of female patients with SLE who were treated with cyclophosphamide at Ramathibodi Hospital, Bangkok, Thailand. Cases were patient who had ovarian toxicity (sustained amenorrhoea >12 months or lack of menstruation for >4 months). CYP2C19 polymorphism was genotyped using PCR-RFLP method. Logistic regression was applied to assess CYP2C19 polymorphism as an effect modifier of cyclophosphamide. Seventy-one patients with SLE were enrolled, of which 36 (59.7%) had ovarian toxicity. CYP2C19*2 allele frequencies were 27.8 and 21.4% in the ovarian and non-ovarian toxicity groups. Patients with CYP2C19*1/*1 genotype and higher cumulative dose of cyclophosphamide (>23.75 g) had the highest odds of ovarian toxicity, i.e. 11.0 (95% CI: 1.2-99.1) times higher than patients with the CYP2C19*1/*2 or *2/*2 genotypes who received less cyclophosphamide (<23.75 g). After adjusting for age at start of treatment, this risk increased to 13.6 (95% CI: 1.1-162.2). Our results suggest that a cumulative cyclophosphamide dose of 23.75 g or higher carries a twofold higher risk of ovarian toxicity and the CYP2C19*1/*1 genotype increases the risk of toxicity a further fivefold.

The aim of the study is to evaluate the prevalence of anti-citrulline antibodies (anti-CCP) versus rheumatoid factor (RF) in a cohort of Thai patients with rheumatoid arthritis (RA), a variety of rheumatic diseases other than RA and healthy controls. The association between anti-CCP and RA disease activity was also examined. Serum from 125 RA patients, 60 from other rheumatic diseases (non-RA) and 60 from healthy controls were tested for IgM RF and second generation anti-CCP. The association between anti-CCP, RF, the Disease Activity Score (DAS 28) and other relevant laboratory tests (CBC, ESR and CRP) were assessed. The sensitivity and specificity of anti-CCP antibody were 58.7 and 100% when compared with 63.5 and 98.3% for RF. These differences were not statistically significant. The anti-CCP outperformed RF in terms of the positive-predictive values (100 vs. 97.6%); however, the negative-predictive values were 72.4% for RF and 69.6% for anti-CCP. The sensitivity when either anti-CCP or RF was positive increased to 71.2%. Nine out of 45 RF-negative patients had a positive anti-CCP test. Anti-CCP was significantly correlated with parameters of inflammation, but not with DAS 28. In conclusion, although anti-CCP is better than RF in distinguishing RA from other rheumatic diseases, its cost, which is 3.3 times higher than the RF test precludes it from replacing RF as a serum marker for Thai patients with RA. The treatment decisions cannot be based on the test alone, as it has no correlation with DAS 28. Its usefulness is in patients with suspected RA who have had a negative RF test.