Objective: To investigate the correlation between MD-1 gene single nucleotide polymorphism (SNP) and bronchial asthma in adults of the Han nationality in Southern China as well as their lung functions.
Methods: From 2006 to 2010, 332 adult asthmatic patients of the Han nationality diagnosed in Nanfang Hospital, Southern Medical University, and 276 healthy volunteers were recruited for the study. The SNPs of MD-1 gene loci rs2233128 and rs7740529 were genotyped by using MassARRAY-IPLEX technology and matrix-assisted laser desorption ionization time of flight mass spectrometry platform (MALDI-TOF-MS). In addition, the lung function of 105 cases initially diagnosed with asthma was measured.
Results: There was no significant difference in sex (χ(2) = 0.50, P = 0.824) and age (t = 0.930, P = 0.357) between the asthma and the healthy groups. Genotypes AG and GG were detected in MD-1 gene at rs2233128 locus and genotypes CC, CT and TT at rs7740529 locus in this Han population at Southern China. Genotyping success rate was 94.74%. The rs2233128 genotype distribution (χ(2) = 0.030, P = 0.863) and allele (χ(2) = 0.029, P = 0.865) showed no significant difference between the asthma and the control groups. However, the rs7740529 genotype distribution (χ(2) = 8.681, P = 0.013) and allele (χ(2) = 8.005, P = 0.005) were significantly different in the asthma group as compared to the control group. Compared with the TT genotype, the rs7740529 of the CC and CC + CT genotypes could dramatically increase the risk of asthma, the odds ratio (95% confidence interval) being 2.451 (1.299 - 4.9626) and 2.172 (1.173 - 4.020), respectively. In the 105 patients initially diagnosed with asthma, FVC% and FEV(1)% were significantly different among the 3 different genotypes (CC, CT and TT) of the rs7740529 locus (F = 18.405, P = 0.000 and F = 25.700, P = 0.000). The percentages of predicted value of FVC and FEV(1) were decreased [(65 ± 12)%, (64 ± 11)%] in the CC genotype as compared to the TT genotypes [(86 ± 9)%, (88 ± 8)%], P < 0.05. There was no significant difference of genotype distribution of rs7740529 in different grades of severity of newly diagnosed asthma (χ(2) = 5.017, P = 0.081).
Conclusions: MD-1 may be a susceptible gene for adult asthma in a Southern Han population in China. Genotype distribution of rs7740529 locus in newly diagnosed patients with asthma may be related to their lung function changes.