Multicentric Genome-Wide Association Study for Primary Spontaneous Pneumothorax

Despite elevated incidence and recurrence rates for Primary Spontaneous Pneumothorax (PSP), little is known about its etiology, and the genetics of idiopathic PSP remains unexplored. To identify genetic variants contributing to sporadic PSP risk, we conducted the first PSP genome-wide association study. Two replicate pools of 92 Portuguese PSP cases and of 129 age- and sex-matched controls were allelotyped in triplicate on the Affymetrix Human SNP Array 6.0 arrays. Markers passing quality control were ranked by relative allele score difference between cases and controls (|RASdiff|), by a novel cluster method and by a combined Z-test. 101 single nucleotide polymorphisms (SNPs) were selected using these three approaches for technical validation by individual genotyping in the discovery dataset. 87 out of 94 successfully tested SNPs were nominally associated in the discovery dataset. Replication of the 87 technically validated SNPs was then carried out in an independent replication dataset of 100 Portuguese cases and 425 controls. The intergenic rs4733649 SNP in chromosome 8 (between LINC00824 and LINC00977) was associated with PSP in the discovery (P = 4.07E-03, ORC[95% CI] = 1.88[1.22-2.89]), replication (P = 1.50E-02, ORC[95% CI] = 1.50[1.08-2.09]) and combined datasets (P = 8.61E-05, ORC[95% CI] = 1.65[1.29-2.13]). This study identified for the first time one genetic risk factor for sporadic PSP, but future studies are warranted to further confirm this finding in other populations and uncover its functional role in PSP pathogenesis.

Asthma and rhinitis have different genetic profiles for IL13, IL17A and GSTP1 polymorphisms

BACKGROUND: Asthma and rhinitis have a complex etiology, depending on multiple genetic and environmental risk factors. An increasing number of susceptibility genes are currently being identified, but the majority of reported associations have not been consistently replicated across populations of different genetic backgrounds. PURPOSE: To evaluate whether polymorphisms of IL4R (rs1805015), IL13 (rs20541), IL17A (rs2275913) and GSTP1 (rs1695) genes are associated with rhinitis and/or asthma in adults of Portuguese ancestry. METHODS: 192 unrelated healthy individuals and 232 patients, 83 with rhinitis and 149 with asthma, were studied. All polymorphisms were detected by real time polymerase chain reaction (PCR) using TaqMan assays. RESULTS: Comparing to controls, significant association with asthma was observed for GSTP1 rs1695 AA genotype (odds ratio (OR) - 1.96; 95% CI - 1.18 to 3.25; p=0.010). The association sustains for allergic asthma (OR - 2.17; 95% CI - 1.23 to 3.80; p=0.007). IL13 rs20541 GG genotype was associated with less susceptibility to asthma (OR - 0.55, 95% CI - 0.33 to 0.94, p=0.028). Among patients, IL17A rs2275913 AA genotype was less associated with asthma than with rhinitis (OR - 0.20; 95% CI of 0.07 to 0.56; p=0.002). A similar association was found for IL13 rs20541 GG genotype (OR - 0.48; 95% CI of 0.25 to 0.93; p=0.031). There were no significant differences in the distribution of allelic and genotypic frequencies between patients and controls for the IL4R polymorphism' analyzed. CONCLUSION: These results support the existence of a significant association between GSTP1 rs1695 and IL13 rs20541 SNPs, with susceptibility to asthma, in the population studied. Different genotype profiles of IL17A and IL13 genes seem to influence the clinical pattern of disease expression mainly confined to the upper airways, as rhinitis, or including the lower airways, as asthma.