PTPRC and bronchiolitis: As expected, maternal smoking during pregnancy was again positively associated with bronchiolitis risk (normalised by CD45+ cells: aOR = 29.78, 95% CI 4.35 to 203.71, P = 0.001; absolute numbers: aOR = 32.96, 95% CI 4.76 to 228.2, P = 0.000).