Nuala J. Meyer, Rui Feng, Mingyao Li, Yang Zhao, Chau-Chyun Sheu, Paula Tejera, Robert Gallop, Scarlett Bellamy, Melanie Rushefski, Paul N. Lanken, Richard Aplenc, Grant E. O’Keefe, Mark M. Wurfel, David C. Christiani, and Jason D. Christie  Am. J. Resp. Crit. Care Med. May 1, 2013 vol. 187 no. 9 950-959

Abstract

Rationale: Acute respiratory distress syndrome (ARDS) behaves as a complex genetic trait, yet knowledge of genetic susceptibility factors remains incomplete.

Objectives: To identify genetic risk variants for ARDS using large scale genotyping.

Methods: A multistage genetic association study was conducted of three critically ill populations phenotyped for ARDS. Stage I, a trauma cohort study (n = 224), was genotyped with a 50K gene-centric single-nucleotide polymorphism (SNP) array. We tested SNPs associated with ARDS at P < 5 × 10−4 for replication in stage II, a trauma case–control population (n = 778). SNPs replicating their association in stage II (P < 0.005) were tested in a stage III nested case–control population of mixed subjects in the intensive care unit (n = 2,063). Logistic regression was used to adjust for potential clinical confounders. We performed ELISA to test for an association between ARDS-associated genotype and plasma protein levels.

Measurements and Main Results: A total of 12 SNPs met the stage I threshold for an association with ARDS. rs315952 in the IL1RN gene encoding IL-1 receptor antagonist (IL1RA) replicated its association with reduced ARDS risk in stages II (P < 0.004) and III (P < 0.02), and was robust to clinical adjustment (combined odds ratio = 0.81; P = 4.2 × 10−5). Plasma IL1RA level was associated with rs315952C in a subset of critically ill subjects. The effect of rs315952 was independent from the tandem repeat variant in IL1RN.

Conclusions: The IL1RN SNP rs315952C is associated with decreased risk of ARDS in three populations with heterogeneous ARDS risk factors, and with increased plasma IL1RA response. IL1RA may attenuate ARDS risk.

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