Xeroderma pigmentosum results from defective nucleotide excision repair (NER). Which of the following clinical associations and complementation groups is correctly paired?

• A XP group C — most severe neurological involvement; De Sanctis-Cacchione syndrome
• B XP group D — exclusively skin cancer without photosensitivity
• C XP group A — most common form; severe photosensitivity, skin cancer, and neurological involvement; De Sanctis-Cacchione syndrome ✓
• D XP group F — most common globally, limited to skin cancer only

Explanation

XP group A (XPA gene, chromosome 9q22) is the most severe and most common form in Japan; it presents with intense photosensitivity, progressive neurological degeneration (sensorineural deafness, microcephaly, ataxia), and De Sanctis-Cacchione syndrome (XP with severe neurological features, dwarfism, gonadal hypoplasia). XP-C is the most common globally but has limited neurological involvement. XP-D (ERCC2/XPD) can show features of Cockayne syndrome overlap. Early sunprotection and regular skin surveillance are critical.

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.