Pharmacogenetics of cyclophosphamide and CYP2C19 polymorphism in Thai systemic lupus erythematosus.

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.

Possible protective effects of the Glu27 allele of beta2-adrenergic receptor polymorphism in Thai asthmatic patients.

The genetic polymorphisms at the 16th (Arg--> Gly) and 27th (Gln-->Glu) amino acid positions of the beta2-adrenergic receptor (ADRB2) may be linked to various asthma-related phenotypes. These include the adverse effects on lung function known to occur following the regular use of albuterol. The study aimed to determine the association between these two ADRB2 SNPs, their haplotypes and the phenotypes in Thai asthmatic patients. One-hundred and thirty asthmatic patients were genotyped at the Arg16Gly and Gln27Glu polymorphisms. Demographic data, disease severities, pulmonary function tests and medication usages were recorded for each patient. The frequencies of the Arg16 and Gln27 alleles were found to be 56.9% and 91.2%, respectively, while the linkage disequilibrium coefficient between the two SNPs was 0.36. Three haplotypes were estimated, i.e., Arg-Gln, Gly-Gln and Gly-Glu with frequencies of 148 (56.9%), 89 (34.2%) and 23 (8.9%), respectively. The mean percentages for predicted FEV1 (%FEV1) for these corresponding haplotypes were 73.5 (SD = 16.3), 72.4 (SD = 17.4) and 80.7 (SD = 13.1), respectively (p = 0.258). Additionally, the number of hospitalizations, emergency visits and inhaled corticosteroid/long-acting beta2-agonist (ICS/LABA) usages were lower in Gln/Glu subjects than for Gln/Gln genotyped patients, with values of 0% versus 11.9% (p = 0.122) for hospitalizations; 4.5% versus 18.8% (p = 0.121) for emergency visits; and 50% versus 76.6%, (p = 0.042) for ICS/LABA usages. The presence of the Glu27 allele in Thai asthmatic patients is associated with a decreased asthma severity, higher %FEV1 values, less frequent hospitalizations and emergency visits, and decreased ICS/LABA usage.

Are anti-citrulline autoantibodies better serum markers for rheumatoid arthritis than rheumatoid factor in Thai population?

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.

Specificity and sensitivity of anti-beta2-glycoprotein I as compared with anticardiolipin antibody and lupus anticoagulant in Thai systemic lupus erythematosus patients with clinical features of antiphospholipid syndrome.

Antibodies to beta(2)-glycoprotein I (anti-beta(2)-GPI) have been reported to have stronger association with clinical antiphospholipid syndrome (APS) than anticardiolipin antibodies (aCL) and lupus anticoagulant (LAC). We investigated the sensitivity and specificity of ELISA for anti-beta(2)-GPI in Thai systemic lupus erythematosus (SLE) patients with clinical features of APS and compared the results with IgG/IgM aCL and LAC to find the test with the best association. The hospital records of 151 Thai SLE patients whose sera had been sent for either IgG/IgM anticardiolipin antibodies or lupus anticoagulant testing were reviewed. Sera of patients either without complete clinical records or those with APS-related manifestations other than vascular thrombosis and pregnancy morbidity (according to the international consensus statement on preliminary classification criteria for definite APS) were excluded. For the remaining subjects (112 patients), their sera were tested for anti-beta(2)-GPI antibody, IgG and IgM anticardiolipin, and lupus anticoagulant. The sensitivity and specificity of each method were compared by using the chi-square test. Among the 112 (74.2%) SLE patients in the study, 35 (31.3%) presented with preliminary clinical criteria for APS (i.e., vascular thrombosis and pregnancy morbidity) whereas 77 (68.7%) did not. The sensitivity and specificity of anti-beta(2)-GPI determination were 57.1 and 79.2%, respectively, whereas those of IgG aCL were 25.7 and 94.8%, of IgM aCL were 5.7 and 98.7%, and of LAC were 44.8 and 77.3%, respectively. The accuracy of the four tests showed similar association with clinical APS (accuracy of test = 72.3, 73.2, 69.6, and 68.3%, respectively). Concerning the sensitivity, specificity, and difficulty of the methods, the combination of anti-beta(2)-GPI and IgG aCL tests was the best for the diagnosis of APS in Thai SLE patients.

Incidence and clinical correlation of anticentromere antibody in Thai patients.

Anticentromere antibodies (ACA) are useful in assessing and classifying patients with mild variant of systemic sclerosis called calcinosis, Raynaud's phenomenon, esophageal dysmotility, sclerodactyly, telangiectasias (CREST) syndrome. From their prognostic significance, we are interested in the prevalence and disease correlation in Thai patients. A total of 3,233 serum samples of patients with any musculoskeletal symptoms were sent for antinuclear antibody determination at Ramathibodi Immunology Laboratory Service between the years 1998 and 2001. Forty sera (1.23%) were ACA positive. These sera were from 27 patients with autoimmune diseases and 13 with nonautoimmune diseases. Among autoimmune group, scleroderma was the most common diagnosis (33.3%) with limited sclerosis being the most frequent variant. The percentages of autoimmune disease were almost the same among the low-titer (1:40) and the high-titer (1:640) groups. The study suggests that the prevalence of ACA in Thai patients is low. The presence of ACA detected in patients with vague musculoskeletal symptoms does not suggest a diagnosis of CREST syndrome. Even high-titer ACA can be found in nonautoimmune diseases.