In the presence of fibrotic ILD, patients had a poorer lung function, as expressed by reduced Forced Expiratory Volume in the first second, % predicted (FEV1%) (p = 0.0346), Forced Vital Capacity, % predicted (FVC%) (p = 0.0271), Total Lung Capacity, % predicted (TLC%) (p = 0.0438) and carbon monoxide diffusing lung capacity, % predicted (DLCO%) (p=0.0030), lower IgA (p = 0.0108) and IgM (p = 0.0249) at diagnosis, and a prevalence in female gender (p = 0.0773). The gene discussed is CD40LG; the disease is interstitial lung disease.