Inclusion Criteria:  Age: 35 years of age or older. Psoriasis subjects: moderate-to-severe psoriasis: PASI (Psoriasis Area and Severity Index ≥12) and a minimum Body Surface Area (BSA) involvement of 10%. Control Subjects: other skin diseases without psoriasis.  Exclusion Criteria:  Patients aged less than 35 years. Patients with previous skin cancer or other cancers. Women of childbearing potential without effective contraceptive method, or lactating women. Prisoners. Psoriasis patients who have had a severe allergic reaction to ILUMYA or any of its ingredients. Psoriasis patients who have chronic or recurring infections. Positive QuantiFERON upon screening will be exclusionary for this trial (latent tuberculosis). Any condition that, in the opinion of the investigator, may interfere with patient's ability to participate in the study, such as severe cognitive impairment or other comorbidities that would, in the opinion of the investigator, predictably limit compliance with the study plan.