Hereditary disease, trasmitted with recessive autosomical modality, the XP is characterized from extreme photosensivity that causes strict and premature damages to level of the cutis and of the eyes. Its incidence is of 1:250000 in Europe and USA, while in Japan the relationship is of 1:40000.
The first descriptions of the disease are found again in the Textbook of Dermatology, published in 1874, “On disease of the skin, including exanthemata” London – New Sydenham Society, Hebra F.-Kaposi M.
The term “Xeroderma Pigmentosum” was coined from the hungarian dermatologist Moritz Kaposi wanting in such a way to indicate a characterized disease picture from pigmented and dry skin.
Hereditary disease, trasmitted with recessive autosomical modality, the XP is characterized from extreme photosensivity that causes strict and premature damages to level of the cutis and of the eyes. Its incidence is of 1:250000 in Europe and USA, while in Japan the relationship is of 1:40000. In the child affected by XP also short exposure to the sun’s ultraviolet rays determines severe cutaneous sunburn with slow resolution, therefore it is from avoiding sources of ultraviolet cancellations categorically, considering moreover that the effects of the exposures are cumulative in the time. The cutaneous displays that characterize the disease, which pigmented specks, dry skin, atrophic lesion, keratoses, bubbles, carry to the apparence, also before the ten years of age, skin cancers.These manifestations are due to the defect of the mechanism of DNA repair, often develop on the face and other sun-exposed parts of the body , including the eyes, lips, and tip of the tongue. The three skin cancers (basal cell carcinoma, squamous cell carcinoma and malignant melanoma) are presents in the XP, therefore the importance of continous controls of the patient is comprised because can be proceeded to immediate removal of whichever skin cancers. To level of the eyes, from the initial phases of the disease, in approximately 80% of the patients they are photophobia, conjunctivitis, ectropion, symblepharon with ulceration, blindness, basal cell carcinoma, squamous cell carcinoma and malignant melanoma. To find that the skin it introduces the first alterations after the six months of life, being moreover normal to the birth. Less of 40% of the patients it survives after the twenty years of age, developing they prematurely numerous skin cancers. While the subjects with attenuated shape of the disease will be able to excedeed the medium age. Beyond the manifestations described to level of the skin and the eyes, 20% of the patients with XP introduce problems of neurological type: deafness, microcephaly, spasticity, ataxia, chorea, ophthalmoplegia and mental delay. The association of XP, hypogonadism, dwarfism, ataxia, mental delay characterized the Syndrome of De Sanctis-Cacchione. The determining causes the XP are from searching in the altered mechanism of repair of the DNA. In normality conditions,the fragment of the altered DNA comes eliminated and replaced from a new fragment syntetized, according to the called mechanism “excision-repair. The basic defect of the XP is from searching in the excision-repair of nucleotide, the NER (Global Genome GG NER – Transcription Coupled TC NER), that it determines altered repair of the DNA damaged from the ultraviolet rays. Eight types of Xeroderma Pigmentosum exsist: every type is characterized from one different genetic alteration of the repair system of the DNA. The diagnosis, beyond that clinical, can be carried out in laboratory, measuring the defect of repair of DNA. This test comes executed using skin or blood of the patient. Therapy for the Xeroderma Pigmentosum does not exist, moreover can be put into effect of the procedures that attenuate the manifestations: protection from the ultraviolet beams, frequent controls of the skin and the eyes, timely removal of the cancerous tissue, neurological controls and last but not least, psycosocial care, remembering that the children with XP are forced living during the nocturnal hours in order to avoid the sunlight.