COL4A1 and systemic sclerosis: Serum COL4 is found more abundantly in patients with systemic sclerosis, especially those with early dcSSc, compared with healthy controls, with serum levels positively correlating with mRSS.7, 18 Johnson and colleagues reported that COL4A1 was one of the key upregulated genes in their inflammatory subset of patients with systemic sclerosis.6