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.
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
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 ...