Additionally, serum levels of both B cell activating factor belonging to the tumor necrosis factor family (BAFF) and a proliferation-inducing ligand (APRIL) are significantly higher in the RP-ILD group than the chronic ILD group, suggesting that these cytokines are involved in the production of anti-MDA5 autoantibodies [188]. Here, TNFSF13B is linked to retinitis pigmentosa 1.