A mother whose previous pregnancy failed to progress into spontaneous labour required induction at term. The child, a boy, now has large dark polygonal scales over the trunk and extensor limbs with sparing of palms and soles, plus corneal opacities. The enzyme deficiency responsible is:

• A Steroid sulfatase ✓
• B Transglutaminase-1
• C Filaggrin
• D SPINK5 (LEKTI)

Explanation

X-linked ichthyosis results from steroid sulfatase (arylsulfatase C) deficiency, giving large 'dirty' polygonal scales with corneal opacities. Placental steroid sulfatase deficiency impairs conversion of fetal DHEAS sulfate to oestriol, causing failure of onset of labour. Filaggrin causes ichthyosis vulgaris, which has fine scales and hyperlinear palms, not corneal involvement.

Reference: Rook's Textbook of Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.