Kim et al. (13) conducted scRNA-seq analyses of skin biopsy tissues from 13 psoriasis patients and 5 healthy volunteers and reported that the majority of T17 cells expressed either IL-17A or IL-17F and only 7.8% of T17 cells co-expressed IL-17A/IL-17F in human psoriasis skin. The gene discussed is IL17F; the disease is psoriasis.