A neonate is born encased in a thick, armor-like hyperkeratotic plate with deep fissures that distort the facial features, causing ectropion and eclabium. The infant develops severe respiratory distress within hours. Mutation of which gene is responsible for this presentation?

• A TGM1
• B FLG
• C STS
• D ABCA12 ✓

Explanation

Harlequin ichthyosis, the most severe congenital ichthyosis, results from autosomal recessive mutations in the ABCA12 gene encoding a lipid transporter essential for lamellar granule function and lipid delivery to the stratum corneum. TGM1 causes classic lamellar ichthyosis, FLG causes ichthyosis vulgaris, and STS deficiency causes X-linked ichthyosis. The distinguishing features here are the massive armor-like plate and extreme ectropion and eclabium at birth.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.