IL-17 and monoclonal TNF inhibitors are preferred in the presence of extensive psoriasis (e.g. >10% body surface area) or severe localized psoriasis at sites associated with high functional impairment or impact (e.g. face, scalp, palms, soles, flexures, genital or nails), ideally in conjunction with a dermatologist (1A, SoA 96%). The gene discussed is IL17A; the disease is psoriasis.