Inclusion Criteria:  Age from 1 to 18 years old Mild, moderate, and severe psoriasis Healthy children, as a comparison group Patients receiving basic and external therapy, receiving systemic therapy with methotrexate and patients receiving therapy with biological drugs (Adalimumab, Etanercept, Ustekinumab) A signed and dated informed consent received from the patient's parents (guardians), as well as from a patient over 14 years of age, to participate in the study Ability to attend control visits within the specified time frame  Exclusion Criteria:  The presence of other concomitant skin diseases in the present or in the past, which could affect the assessment of the effect of the study drugs on the course of psoriasis Use of other genetically engineered biological preparations in therapy Participation in other clinical trials Extensive or complete disability, significantly limiting personal care or determining the inability to carry it out Immunodeficiency disease The presence in the past or present of any serious and / or unstable concomitant disease The course of a viral, bacterial, fungal or parasitic infection