One previous study evaluating CHIT1 activity levels in patients with interstitial lung disease (ILD) showed that serum CHIT1 activity was only elevated in sarcoidosis patients, while in patients with IPF and patients with systemic sclerosis-associated ILD (SSc-ILD) serum CHIT1 activity levels were not different compared to controls. The gene discussed is CHIT1; the disease is systemic sclerosis.