Incontinentia pigmenti (Bloch-Sulzberger syndrome) follows which inheritance pattern, and what is the molecular defect?

• A X-linked recessive; mutation in PORCN gene affecting Wnt signalling
• B X-linked dominant; mutation in IKBKG (NEMO) gene affecting NF-κB signalling ✓
• C Autosomal dominant; mutation in NOTCH1 gene
• D X-linked dominant; mutation in EBP gene affecting cholesterol biosynthesis

Explanation

Incontinentia pigmenti is an X-linked dominant condition caused by mutations in IKBKG (IκB kinase gamma/NEMO), which is essential for NF-κB pathway activation. It is lethal in males (X-hemizygous); affected females show the classic 4 stages: vesicular, verrucous, hyperpigmented (whorled 'marble cake' pattern following Blaschko's lines), and hypopigmented/atrophic. Extracutaneous features include dental, ocular, and CNS manifestations. PORCN mutations cause focal dermal hypoplasia (Goltz syndrome).

Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.