Diseases in which TYK2 pathway has been demonstrated to be involved and for which clinical benefit of deucravacitinib has been reported include discoid lupus erythematosus, systemic lupus erythematosus, alopecia areata, lichen planus, palmoplantar pustulosis, psoriatic arthritis, systemic sclerosis, interstitial pneumonia, inflammatory bowel disease, and chronic recurrent multifocal osteomyelitis. Here, TYK2 is linked to alopecia areata.