Syndromes With Defective DNA Repair

Figure 2.19
A: Xeroderma pigmentosum
(Courtesy of Dr. Michelle
B. Bain)
B: Xeroderma pigmentosum
(Courtesy of Dr. Michelle
B. Bain)
C: Rothmund-Thomson
(Reprint from Burgdorf WH,
Plewig G, Wolff HH,
Landthaler M, eds.
Braun-Falco’s Dermatology. 3rd
ed. Heidelberg: Springer; 2009)

Xeroderma Pigmentosum (XP) (Figure 2.19A, B)

AR, due to defect in DNA repair
Seven complementation groups (A–G) and one XP variant described, each encoding different proteins in the nucleotide excision repair (NER) pathway (except XP variant)
Presents with marked photosensitivity, early onset of all major skin malignancies, exaggerated sunburn following minimal sun exposure, solar lentigines by age of 2, ocular abnormalities (photophobia, keratitis, corneal opacification, vascularization), neurologic abnormalities (progressive deafness)
XP variant (mutation in DNA polymerase): no neurologic abnormalities
DeSanctis–Cacchione syndrome (Gr. A): severe neurologic abnormalities (MR, deafness, ataxia)

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Syndromes With Defective DNA Repair