A 3-year-old boy presents with diffuse scaling, sparse hair, photophobia, and intellectual disability. His urine shows elevated 7-dehydrocholesterol. He has mutations in the CHILD syndrome-related pathway. The condition affecting cornified envelope cross-linking along with sterol metabolism is:

• A CHILD syndrome (NSDHL mutations)
• B Conradi-Hünermann-Happle syndrome (EBP mutations)
• C Sjögren-Larsson syndrome (ALDH3A2 mutation, fatty aldehyde dehydrogenase deficiency) ✓
• D Refsum disease (phytanoyl-CoA hydroxylase deficiency)

Explanation

Sjögren-Larsson syndrome is an autosomal recessive disorder caused by mutations in ALDH3A2 (fatty aldehyde dehydrogenase deficiency), causing accumulation of fatty alcohols and aldehydes. It presents with ichthyosis, spastic diplegia/tetraplegia, and intellectual disability. The 'glistening dots' on macular OCT are pathognomonic. CHILD syndrome (unilateral ichthyosis, limb defects) involves NSDHL; Conradi-Hünermann involves EBP (X-linked dominant); Refsum disease involves phytanic acid accumulation.

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

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Written and medically reviewed by the StethoPrep medical team.