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Genetic disorder with xeroderma pigmentosum and progressive neurologic degeneration.

Xerodermic Idiocy of De Sanctis and Cacchione.

Not known for De Sanctis Cacchione syndrome; however, the incidence of xeroderma pigmentosum is estimated to be 1:250,000 in general population, and the percentage of patients with associated neurologic changes is 15 to 20%. Both genders are equally affected. Seems to occur in all ethnic groups.

Autosomal recessive.

Xeroderma pigmentosum causes pigmentary and atrophic skin changes as a result of a defective ability to repair normally occurring DNA changes (cross-linkage of thymidine nucleotides, called dimers) following exposure to ultraviolet (UV) light. The nucleotide excision repair mechanism, responsible in healthy individuals for elimination of these dimers, fails to excise and replace them by normal nucleotides. Early and diffuse neuronal death occurs in correlation with the degree of inability to repair DNA, which may account for the neurologic changes in this subgroup of xeroderma pigmentosum. Polyneuropathy has been attributed to diffuse axonal loss in peripheral nerves in affected patients.

Clinical and family history. Cytogenetic testing can be used to elucidate the complementation subtype of xeroderma pigmentosum. The De Sanctis Cacchione syndrome usually is associated with subtypes A (subgroup with the most profound defect and basically absent DNA repair function) and D (subgroup with the highest rate [about half of patients] of neurologic involvement) but may occur with any of the seven subtypes (A through G).

Skin changes include atrophy, photosensitivity, and hyperpigmentation and hypopigmentation. Skin cancer is the major cause of morbidity in these patients, with basal cell and squamous cell carcinoma being the most common tumors, presenting at a median age of approximately 8 years. The risk of developing a malignant melanoma is up to 2000-fold higher than in a healthy person. Commonly, these skin tumors are multiple and do not spare the eye. Interestingly, and sadly enough, patients also suffer from a significantly higher incidence of other tumors. The most common neurologic symptoms are mental retardation, spasticity, ataxia, microcephaly, epilepsy, deafness, areflexia, and choreoathetosis. Other signs include the eye abnormalities (photophobia, keratitis, impaired vision), dwarfism, and gonadal hypoplasia.

Communication will be difficult because of mental impairment, possible deafness, and impaired vision. Careful positioning and padding are required because of the vulnerability of the skin. Mouth opening may be restricted as a result of skin atrophy and scarring. According to a case report, volatile anesthetic agents should be avoided in patients with xeroderma pigmentosum because of in vitro evidence that the defective DNA repair may be further worsened by exposure to halothane. Vascular access can be challenging in the presence of extensive skin changes. Be careful when applying adhesive tapes and strips and even more so when removing them.

Secondary to liver enzyme induction, chronic anticonvulsant medication may affect the metabolism of predominantly hepatic eliminated drugs.

Xeroderma Pigmentosum (XP): Rare autosomal recessive ...

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