They determined that only 25 common dysregulated genes were in keloids in 7 studies where collagen, type I, alpha 1 (COL1A1); collagen, type I, alpha 2 (COL1A2); collagen, type V, alpha 2 (COL5A2); and collagen, type VI, alpha 1 (COL6A1) were systematically upregulated. Here, COL1A1 is linked to keloid.