Strict sun protection results in minimal skin changes in a patient with xeroderma pigmentosum and a novel c.2009delG mutation in XPD (ERCC2)

Abstract:  We examined the clinical, molecular and genetic features of a 16-year-old boy (XP2GO) with xeroderma pigmentosum (XP) and progressive neurological symptoms. The parents are not consanguineous. Increased sun sensitivity led to the diagnosis of XP at 2 years of age and a strict UV protection scheme was implemented. Besides recurrent conjunctivitis and bilateral pterygium, only mild freckling was present on his lips. He shows absent deep tendon reflexes, progressive sensorineural deafness and progressive mental retardation. MRI shows diffuse frontal cerebral atrophy and dilated ventricles. Symptoms of trichothiodystrophy (brittle hair with a tiger-tail banding pattern on polarized microscopy) or Cockayne syndrome (cachectic dwarfism, cataracts, pigmentary retinopathy and spasticity) were absent. XP2GO fibroblasts showed reduced post-UV cell survival (D₃₇ = 3.8 J/m²), reduced nucleotide excision repair, reduced expression of XPD mRNA and an undetectable level of XPD protein. Mutational analysis of the XPD gene in XP2GO revealed two different mutations: a common p.Arg683Trp amino acid change (c.2047C>T) known to be associated with XP and a novel frameshift mutation c.2009delG (p.Gly670Alafs*39). The latter mutation potentially behaves as a null allele. While not preventing neurological degeneration, early diagnosis and rigorous sun protection can result in minimal skin disease without cancer in XP patients.     

Readthrough of stop codons by use of aminoglycosides in cells from xeroderma pigmentosum group C patients

Readthrough of premature termination (stop) codons (PTC) is a new approach to treatment of genetic diseases. We recently reported that readthrough of PTC in cells from some xeroderma pigmentosum complementation group C (XP‐C) patients could be achieved with the aminoglycosides geneticin or gentamicin. We found that the response depended on several factors including the PTC sequence, its location within the gene and the aminoglycoside used. Here, we extended these studies to investigate the effects of other aminoglycosides that are already on the market. We reasoned that topical treatment could deliver much higher concentrations of drug to the skin, the therapeutic target, and thus increase the therapeutic effect while reducing renal or ototoxicity in comparison with systemic treatment. Our prior clinical studies indicated that only a few percent of normal XPC expression was associated with mild clinical disease. We found minimal cell toxicity in the XP‐C cells with several aminoglycosides. We found increased XPC mRNA expression in PTC‐containing XP‐C cells with G418, paromomycin, neomycin and kanamycin and increased XPC protein expression with G418. We conclude that in selected patients with XP, topical PTC therapy can be investigated as a method of personalized medicine to alleviate their cutaneous symptoms.     

Defective DNA repair in cultured melanocytes from xeroderma pigmentosum patients

The DNA repair of ultraviolet (UV)-induced damages in primary cultured melanocytes from xeroderma pigmentosum (XP) patients and normal subjects were studied by measuring unscheduled DNA synthesis (UDS) on autoradiographs. Melanocytes were cultured in alpha-minimum essential medium (alpha-MEM) supplemented with 10% fetal calf serum (FCS), 12-O-tetradecanoyl-phorbol-13 acetate (TPA), and geneticin. The levels of UDS in XP melanocytes were compared with those in normal melanocytes. In both normal and XP melanocytes, post-UV-UDS increased dose-dependently at doses of 5-10 J/m2. XP melanocytes exhibited various levels of defect in DNA repair, depending on the type of XP. Melanocytes from XP-A patients displayed very low levels of UDS, only 6.2-8.4% that of the normal melanocytes. However, UDS values in melanocytes from intermediate groups, XP-D, XP-E, and XP-F, were relatively high, 37.2-53.5% of the control in XP-D, 50.0-66.5% in XP-E, and 38.2-46.7% in XP-F, respectively. Melanocytes from XP-variant patients exhibited almost normal levels of UDS, 87.7-91.6% of those from normal subjects. The levels of UDS in XP melanocytes were very similar to those in fibroblasts isolated from the same specimens.     

着色性干皮病伴发血管内皮细胞瘤1例

患儿女，9岁，全身皮肤色素斑8年余伴肿物3个月。检查：面部，颈部，胸背上部曝光部位及四肢皮肢欢迎光临性色素沉着斑，颜色呈暗棕色及黑色，深浅不一，间杂白色萎缩性斑点，鼻部，背部，前臂可见大小不等疣状赘生物，触之易出血，背部赘生物作组织病理检查示：真皮内毛细血管呈片状和结节状增生，排列紧密，内皮细胸增生，聚集成实性束或团块，部分呈短俊形，有轻度异形性，可见少量核分裂像，部分区域血管扩张，形状不规则，管壁较薄，内皮细胞增生不明显，管周可见稀疏淋巴细胞，免疫组化染色示：CD31呈灶性阳性（ ），CD34阳性（ ）。诊断：着色性上皮病伴发血管内皮细胞瘤。     

Xeroderma pigmentosum complementation group G patient with a novel homozygous missense mutation and no neurological abnormalities

We describe an unusual xeroderma pigmentosum (XP) patient with a mutation in XP complementation group G, representing only the third reported Japanese XP-G patient. A 40-year-old men (XP3HM), born from consanguineous parents experienced sun sensitivity and pigmentary changes of sun-exposed skin since childhood. He developed a squamous cell carcinoma on his lower lip at the age of 40. He has neither neurological abnormalities nor Cockayne syndrome. The primary fibroblasts of the patient were hypersensitive to killing by UV (D(0) = 0.6 J/m(2)) and the post-UV unscheduled DNA synthesis was 8% of normal. Host cell reactivation complementation analysis implicated XP complementation group G. We identified a novel homozygous mutation (c.194T>C) in a conserved portion of the XPG(ERCC5) gene, resulting in a predicted amino acid change; p.L65P. We confirmed that this genetic change reduced DNA repair thus linking this mutation to increased skin cancer.     

Non-radioisotope method for diagnosing photosensitive genodermatoses and a new marker for xeroderma pigmentosum variant

Xeroderma pigmentosum (XP) is an autosomal recessive disorder characterized by photo-induced deterioration of the skin, which often leads to the early development of skin cancers. To diagnose patients with XP and the related disorder Cockayne syndrome (CS), our laboratory has established a simple autoradiographic method that examines three cellular markers of DNA repair: unscheduled DNA synthesis (UDS), recovery of RNA synthesis (RRS) and recovery of replicative DNA synthesis (RDS). However, it is very laborious to measure the three markers using tritiated thymidine or uridine; therefore, we developed a non-isotope method for diagnosing XP and CS. Fibroblasts from the patient were labeled with bromodeoxyuridine (BrdU) instead of tritiated thymidine to measure UDS and RDS, or were labeled with bromouridine (BrU) instead of tritiated uridine to measure RRS. Incorporated BrdU or BrU could be detected using the immunofluorescence method. Moreover, we discovered a new useful marker for XP variant based on checkpoint activity. The non-radioisotope method and the new marker described here comprise an easy way to diagnose XP and CS.     

Cyclosporin A inhibits nucleotide excision repair via downregulation of the xeroderma pigmentosum group A and G proteins, which is mediated by calcineurin inhibition

Cyclosporin A (CsA) inhibits nucleotide excision repair (NER) in human cells, a process that contributes to the skin cancer proneness in organ transplant patients. We investigated the mechanisms of CsA-induced NER reduction by assessing all xeroderma pigmentosum (XP) genes (XPA-XPG). Western blot analyses revealed that XPA and XPG protein expression was reduced in normal human GM00637 fibroblasts exposed to 0.1 and 0.5 μm CsA. Interestingly, the CsA treatment reduced XPG, but not XPA, mRNA expression. Calcineurin knockdown in GM00637 fibroblasts using RNAi led to similar results suggesting that calcineurin-dependent signalling is involved in XPA and XPG protein regulation. CsA-induced reduction in NER could be complemented by the overexpression of either XPA or XPG protein. Likewise, XPA-deficient fibroblasts with stable overexpression of XPA (XP2OS-pCAH19WS) did not show the inhibitory effect of CsA on NER. In contrast, XPC-deficient fibroblasts overexpressing XPC showed CsA-reduced NER. Our data indicate that the CsA-induced inhibition of NER is a result of downregulation of XPA and XPG protein in a calcineurin-dependent manner.     

Dermoscopy of skin lesions in two patients with xeroderma pigmentosum

BACKGROUND: Xeroderma pigmentosum (XP) is a rare disorder produced by a genetic defect in the repair of DNA damage caused by ultraviolet radiation. The early diagnosis of malignant skin tumours is crucial in the survival of patients with XP, but this is not easy even for experienced dermatologists due to the presence of a high number of actinic lesions. Dermoscopy is a new diagnostic method that increases the diagnostic accuracy for skin tumours. OBJECTIVES: To describe the clinical and dermoscopic features of different benign and malignant lesions [focusing on malignant melanoma, basal cell carcinoma (BCC) and benign melanocytic naevi] in two patients with XP. METHODS: Three dermatologists with experience in pigmented skin lesions and dermoscopy examined two siblings with XP over a period of 54 months. Diagnosis of skin tumours was obtained using clinical examination and dermoscopy with 10-fold magnification and digital images. All the tumours with criteria of malignancy were excised for further histopathological analyses. RESULTS: Multiple skin tumours showing some degree of pigmentation were detected in the patients. Clinical and dermoscopic examination allowed the discrimination of four melanomas (three of them in situ), 26 BCCs and five dysplastic naevi from other pigmented skin lesions. The features and parameters previously described for dermoscopy were shown to be appropriate for the recognition of tumours in our patients with XP. Generalized actinic lentigos were distinguished from BCCs by the presence of a delicate brown pigmented network. Fine vessels from poikiloderma were differentiated from the arborizing telangiectasia of BCC. CONCLUSIONS: The dermoscopic findings in the tumours were similar to those previously described in patients not affected by XP. Diagnosis by dermoscopic pattern analyses allowed a correct classification of malignant tumours in these cases.     

Xeroderma pigmentosum clinical practice guidelines

Xeroderma pigmentosum (XP) is a genetic photosensitive disorder in which patients are highly susceptibe to skin cancers on the sun‐exposed body sites. In Japan, more than half of patients (30% worldwide) with XP show complications of idiopathic progressive, intractable neurological symptoms with poor prognoses. Therefore, this disease does not merely present with dermatological symptoms, such as photosensitivity, pigmentary change and skin cancers, but is “an intractable neurological and dermatological disease”. For this reason, in March 2007, the Japanese Ministry of Health, Labor and Welfare added XP to the neurocutaneous syndromes that are subject to government research initiatives for overcoming intractable diseases. XP is one of the extremely serious photosensitive disorders in which patients easily develop multiple skin cancers if they are not completely protected from ultraviolet radiation. XP patients thus need to be strictly shielded from sunlight throughout their lives, and they often experience idiopathic neurodegenerative complications that markedly reduce the quality of life for both the patients and their families. Hospitals in Japan often see cases of XP as severely photosensitive in children, and as advanced pigmentary disorders of the sun‐exposed area with multiple skin cancers in adults (aged in their 20–40s), making XP an important disease to differentiate in everyday clinical practice. It was thus decided that there was a strong need for clinical practice guidelines dedicated to XP. This process led to the creation of new clinical practice guidelines for XP.     

Xeroderma pigmentosum: recent clinical and photobiological aspects.

In Japan, more than 400 patients with xeroderma pigmentosum (XP) have been registered. The major groups are XP-A and variant, while clinically mild types of XP with intermediate levels of unscheduled DNA synthesis (UDS) have recently been increasing. The classical type of XP-A and some of the XP-D patients exhibit neurologic abnormalities. XP individuals display a marked increase in the frequency of skin malignancy. Development of skin malignancies appears to be related to the level of DNA repair capacity; the lower the capacity, the earlier and more frequently the skin tumors develop. Furthermore, the incidence of internal malignancy in XP patients is at least ten times higher than that for the Japanese general population over the age of 40 years. Cultured fibroblasts from XP patients exhibit higher sensitivity not only to UVC but also to UVB. The cellular sensitivity to UVB may correlate to photosensitivity in vivo from a study on a group E patient who showed age-related changes in photosensitivity and cellular sensitivity to UVB. We have also reviewed current status of molecular genetics in XP.     

DNA-based prenatal diagnosis in a Chinese family with xeroderma pigmentosum group A

BACKGROUND: Xeroderma pigmentosum (XP) is a group of autosomal recessive diseases characterized by hypersensitivity to ultraviolet rays. Among its eight complementation groups, XP group A (XPA) is the most severe type. The XPAC gene has been identified as the defective gene in XPA patients. OBJECTIVES: To examine genomic DNA from a Chinese family with XPA, to determine the XPAC mutation and, after genetic counselling, to undertake DNA-based prenatal diagnosis in a subsequent pregnancy. METHODS: Fetal DNA was extracted from amniotic fluid and used to amplify exon 5 of XPAC containing the potential mutation. Direct sequencing and restriction endonuclease digestion were used for prenatal diagnosis. RESULTS: We identified a homozygous nonsense XPAC mutation of 631C-->T, which results in an R211X mutation in XPA protein, in the proband. Both her parents are heterozygous. Prenatal diagnosis demonstrated a heterozygous sequence predicting an unaffected child, and a healthy girl was born. CONCLUSIONS: These data provide the first example of a DNA-based prenatal test for genodermatosis in China.     

Xeroderma pigmentosum variant associated with multiple cancers

A 62-year-old Japanese man with xeroderma pigmentosum (XP) variant is reported. The patient had developed at least 6 basal cell carcinomas, a squamous cell carcinoma, and a malignant melanoma on sun-exposed areas, and an atypical carcinoid on the right lung. In vivo phototesting showed a normal response. The minimal erythema dose of ultraviolet B (UVB) was not lowered and no delayed peaking of the erythema reaction was observed. His skin fibroblasts exhibited higher sensitivity to UV irradiation, but a normal level of unscheduled DNA and RNA synthesis. Cell fusions with XP group A, C, D, E, F, and G cells after UV irradiation were all complemented. Previous reports together with this case suggest that older XP variant patients have a high frequency of not only skin cancers, but also internal malignancies.     

Incidence of xeroderma pigmentosum in Larkana, Pakistan: a 7-year study

Xeroderma pigmentosum (XP) is a rare autosomal recessive inherited disorder caused by a defect in the normal repair of DNA of various cutaneous cell types damaged by exposure to ultraviolet radiation. We present our 7-year experience with 36 XP patients who either visited the Department of Dermatology or were seen in the medical camps arranged in remote areas for patients' welfare, from 1995 to 2001. For ease of discussion we classified all cases into the following subgroups on clinical grounds only: mild, those with light brown freckles on the face alone; moderate, those with dark brown freckles with burning on the face, neck, ears, chest, hands and photophobia but without other associated obvious cutaneous and ocular changes; severe, those with extensive dark brown freckles with burning on the exposed parts as well as on the unexposed parts of the body, i.e. the chest, back, abdomen and arms including other associated cutaneous and ocular changes such as ulcers and malignancy. Of 36 patients, three (8.3%) were classified as mild, nine (25%) moderate and 24 (66.7%) severe; there were 18 males and 18 females, age range 2-30 years (mean 8.9 years). Seventeen patients had cutaneous changes: actinic keratosis, keratoacanthoma, fissures and ulcerative nodules on the exposed parts of the body. Four patients had wide ulcers, along with mass formation and severe pigmentation on the face, neck and head. Twenty-nine patients developed ocular symptoms: photophobia, conjunctivitis, corneal keratitis and lid ulcer. One patient had complete loss of vision. Histopathological findings revealed that six patients had squamous cell carcinoma (SCC) on the face, head, ear or lip. More than one sibling (two to four) was affected in four families. The majority of cases (20/36, 55.6%) were from the Brohi tribe (skin type III), while the remaining cases (16/36, 44.4%) were from the Sindhi population (skin type IV). The large number of XP patients seen in those with skin type III (Brohi tribe) compared with skin type IV (Sindhi population) indicates that the skin type and the race has a considerable value in the pathogenesis of XP. Furthermore, 24 of 36 patients were in the severe group and six of these had SCC. Moreover, no neurological abnormalities were observed in our patients. All patients were treated according to disease severity by prescribing oral antibiotics, local steroids, sunscreens and/or chemotherapy followed by irradiation in malignant cases. Two patients died because of extensive SCC.     

Multiple facial basal cell carcinomas in xeroderma pigmentosum treated with topical imiquimod 5% cream

Xeroderma pigmentosum (XP) is an autosomal recessive disease characterized by solar sensitivity, photophobia, early onset of freckling, and solar‐induced cutaneous neoplastic changes. Management of patients with XP is a therapeutic challenge as they usually develop multiple cutaneous malignancies, making surgical therapy difficult, and continue to form skin malignancies at a high rate. We describe a 30‐year‐old Chinese man with XP who had been previously treated with excision and dermatoplasty. Upon recurrence of multiple superficial, ulcerative, and pigmented lesions, imiquimod 5% cream was recommended for 4 months. His multiple facial lesions demonstrated an excellent response to topical imiquimod 5% cream with minor side effects. This favorable response indicates that topical application of imiquimod 5% cream is an effective means of treating multiple basal cell carcinomas in XP.     

Useful applications of DNA repair tests for differential diagnosis of atypical dyschromatosis symmetrica hereditaria from xeroderma pigmentosum

Dyschromatosis symmetrica hereditaria (DSH) is a hereditary skin disease characterized by the presence of pigmented and hypopigmented macules on the extremities and freckles on the face. However, if clinical features are not fully developed in infantile patients, it is difficult to differentiate DSH from xeroderma pigmentosum by clinical features alone. A 2-year-old boy (patient 1), revealed atypical features of DSH with slight susceptibility to sunburn. However, his grandfather (patient 4) who was 67 years old, revealed typical features of DSH, which helped to make an exact diagnosis in patient 1. For patient 2, a 5-year-old boy, and patient 3, a 3-year-old girl, it was more difficult to make a diagnosis because there were no family members with DSH features. DNA repair ability was tested for all four cases by means of unscheduled DNA synthesis and colony formation of skin fibroblasts after ultraviolet light irradiation, which resulted in an accurate diagnosis of DSH. We propose that these tests be performed to make a diagnosis of DSH in the case of poor or atypical clinical symptoms.     

Diagnosis of eight groups of xeroderma pigmentosum by genetic complementation using recombinant adenovirus vectors

Because patients with xeroderma pigmentosum (XP) must avoid ultraviolet (UV) light from an early age, an early diagnosis of this disorder is essential. XP is composed of seven genetic complementation groups, XP‐A to ‐G, and a variant type (XP‐V). To establish an easy and accurate diagnosis of the eight disease groups, we constructed recombinant adenoviruses that expressed one of the XP cDNA. When fibroblasts derived from patients with XP‐A, ‐B, ‐C, ‐D, ‐F or ‐G were infected with the adenovirus expressing XPA, XPB, XPC, XPD, XPF or XPG, respectively, and UV‐C at 5–20 J/m² was irradiated, cell viability was clearly recovered by the corresponding recombinant adenoviruses. In contrast, XP‐E and XP‐V cells were not significantly sensitive to UV irradiation and were barely complemented by the matched recombinant adenoviruses. However, co‐infection of Ad‐XPA with Ad‐XPE increased survival rate of XP‐E cells after UV‐C exposure. When XP‐V cell strains, including one derived from a Japanese patient, were infected with Ad‐XPV, exposed to UV‐B and cultured with 1 mmol/L of caffeine, flow cytometry detected a characteristic decrease in the S phase in all the XP‐V cell strains. From these results, the eight groups of XP could be differentiated by utilizing a set of recombinant adenoviruses, indicating that our procedure provides a convenient and correct diagnostic method for all the XP groups including XP‐E and XP‐V.     

Enzyme therapy of xeroderma pigmentosum: safety and efficacy testing of T4N5 liposome lotion containing a prokaryotic DNA repair enzyme

Xeroderma pigmentosum (XP) is a rare genetic disease in which patients are defective in DNA repair and are extremely sensitive to solar UV radiation exposure. A new treatment approach was tested in these patients, in which a prokaryotic DNA repair enzyme specific for UV-induced DNA damage was delivered into the skin by means of topically applied liposomes to supplement the deficient activity. Acute and chronic safety testing in both mice and humans showed neither adverse reactions nor significant changes in serum chemistry or in skin histology. The skin of XP patients treated with the DNA repair liposomes had fewer cyclobutylpyrimidine dimers in DNA and showed less erythema than did control sites. The results encourage further clinical testing of this new enzyme therapy approach.