A recent prospective immune profiling study conducted on Australian extremely preterm infants (defined in this study as < 29 weeks gestation) observed a strong association between T-helper lymphocyte type 2 (Th2) immune polarization (using the surrogate marker interleukin-4, IL-4+, in T-cells) from birth and bronchopulmonary dysplasia. The gene discussed is IL4; the disease is bronchopulmonary dysplasia.