A 20-year-old man develops extensive plaque psoriasis with onset at age 16. His father and paternal aunt have psoriasis, and his disease is severe despite topical therapy. Genetic studies would most likely demonstrate an association with which HLA allele?
- A HLA-B27
- B HLA-DR4
- C HLA-Cw6 ✓
- D HLA-DQ2
Correct answer: C. HLA-Cw6
Explanation
Type 1 psoriasis begins before 40 years of age, shows strong family history, more extensive and severe disease, and is strongly linked to HLA-Cw6 within the PSORS1 susceptibility locus on chromosome 6p. Type 2 psoriasis starts after 40, lacks family history, and runs a milder course without this association. HLA-B27 relates to axial psoriatic arthritis and ankylosing spondylitis, HLA-DR4 to rheumatoid arthritis, and HLA-DQ2 to celiac disease and dermatitis herpetiformis.
Reference: Fitzpatrick's Dermatology, 9th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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