Bernstein et al. investigated the effect of genetic nucleotide polymorphisms of interleukin 4 receptor alpha (IL4RA), IL-13, and CD14 in isocyanate exposed workers and found a statistically significant association of diisocyanate asthma with the IL4RA (I50V), IL13 (R110Q), and CD14 (C159T) genotype combinations, but only in HDI exposed workers and not in those exposed to MDI or TDI. This evidence concerns the gene IL4R and asthma.