Differential association of tumour necrosis factor-alpha single nucleotide polymorphism (-308) with tuberculosis and bronchial asthma.

BACKGROUND: Tumour necrosis factor (TNF)-alpha is a pleiotropic, pro-inflammatory cytokine of 17 kDa, whose gene is localized on the short arm of chromosome 6. It has a G-308A polymorphism in the promoter region, which is known to be associated with its differential production; the A allele being the high producer. The circulating level of TNF-alpha is under genetic control and implicated in the pathophysiology of asthma and tuberculosis. Since raised levels of TNF-alpha have been found in asthma and tuberculosis, we looked for the association of TNF-alpha G-308A polymorphism in patients with these diseases. METHODS: A total of 300 blood samples from patients (155 with asthma, 145 tuberculosis) and 211 normal healthy controls were collected. The G-308A polymorphism was studied using amplification refractory mutation system analysis. RESULTS: The distribution of G/A alleles in the two patient groups when compared with normal controls revealed a statistically significant association with asthma (p = 0.016) but not with tuberculosis (p = 0.178). CONCLUSION: The data support the common variant common disease hypothesis, which emphasizes that common genetic variations may participate as critical players in inciting common diseases.

Diagnosing different stages of hepatitis B infection using a competitive polymerase chain reaction assay.

PURPOSE: Different stages of hepatitis B virus (HBV) infection can be defined by serum HBV DNA levels. This study attempts to (1) investigate serum HBV DNA levels in inactive carriers and patients with chronic HBV (CHB) infection and (2) define cut-off value between inactive carriers and HBeAg (precore antigen of HBV) negative CHB patients in Indian population. METHODS: One hundred and forty samples encompassing 42 inactive HBsAg carriers and 98 CHB patients (53 HBeAg-positive and 45 HBeAg-negative) were analysed. Serum HBV DNA levels were determined employing an in-house competitive polymerase chain reaction (cPCR) assay. RESULTS: The HBeAg-positive patients were found to have the maximum median HBV DNA load, which was significantly higher than the HBeAg-negative ones (median; 1.25 x 10(8) vs. 2.30 x 10(5) copies/mL ; P<0.05). Interestingly, the latter group has significantly higher HBV DNA levels than the inactive carriers (median; 2.30 x 10(5) vs. 4.28 x 10(3) copies/mL; P<0.05). The 2.5 x 10(4) copies/ml HBV DNA levels were optimal for discriminating CHB patients (HBeAg-negative) from inactive carriers with 75.6 and 78.6% sensitivity and specificity, respectively. CONCLUSIONS: Despite the extensive overlapping of HBV DNA levels in inactive carriers and HBeAg negative CHB patients, 2.5 x 10(4) copies/mL is the most favourable cut-off value to classify these individuals and would be imperative in the better management of this dreadful disease.