A child with xeroderma pigmentosum and bone marrow failure

Oral mucosa involvement in pediatric patients with xeroderma pigmentosum: a comprehensive review

BACKGROUND

Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder presenting with an inability to repair UV-induced DNA damage. This can lead to the development of neoplasms affecting multiple organ systems, with onset often in childhood. Unfortunately, no cure currently exists for XP, and management strategies focus on sun protection and early intervention for malignancies. Although most skin problems in XP patients are UV induced, various oral lesions are also described. However, the literature has not extensively characterized the oral manifestations and their prognostic significance.

METHODS

We conducted a comprehensive review to evaluate the prevalence and nature of oral mucosal lesions in pediatric XP patients.

RESULTS

Our literature search yielded 130 pediatric XP patients with oral involvement and 210 associated tumoral or non-tumoral lesions. Squamous cell carcinoma was the most common type of oral mucosal tumor reported, with other malignancies including basal cell carcinoma, melanoma, angiosarcoma, fibrosarcoma, and trichilemmal carcinoma.

CONCLUSION

Given the potential morbidity and mortality associated with oral mucosal tumors in XP patients, our study aims to raise awareness of these manifestations. Early diagnosis and treatment are crucial for managing these lesions effectively, and routine oral exams should be considered a critical component of dermatological evaluations for XP patients, especially in the pediatric age group.

Unresectable and chemoresistant conjunctival squamous cell carcinoma on xeroderma pigmentosum treated by salvage radiation therapy: A case report and a review of the literature

Xeroderma pigmentosum (XP) is a rare genetic disease, which vital prognosis is conditioned by the occurrence of cancers essentially of the skin and ocular surfaces, requiring an early and adapted management. Radiation therapy (RT) is a very effective modality in the therapeutic arsenal alongside surgery, but it remains underused as it is wrongly considered to be deleterious for these patients. In this article, we report the case of a 10-years-old girl with XP treated with external beam RT for a squamous cell carcinoma (SCC) of the right ocular conjunctiva. The clinical tolerance was excellent and we obtained a good tumoral response. Therefore, the place of RT in these patients could/should be reconsidered, especially since these suspicions have still not been confirmed.

Increased risk of internal tumors in DNA repair-deficient xeroderma pigmentosum patients: analysis of four international cohorts

Background

Xeroderma pigmentosum (XP) is a rare, autosomal, recessive DNA repair-deficiency disorder with a frequency of 1–3 per million livebirths in Europe and USA but with higher frequencies in isolated islands or in countries with a high level of consanguinity. XP is characterized by high incidence of skin cancers on sun-exposed sites. Recent improvement in life expectancy of XP patients suggests an increased risk of frequently aggressive and lethal internal tumors. Our purpose was to quantify relative risks of internal tumor development for XP patients by tumor type, XP-subtype, patients’ ages and ethnicity through comparison with the US general population.

Methods

We analyzed four independent international well-characterized XP cohorts (from USA, UK, France and Brazil) with a total of 434 patients, where 11.3% developed internal tumors and compared them to the American general population. We also compiled, through PubMed/Medline, a dataset of 89 internal tumors in XP patients published between 1958 and 2020.

Results

In the combined 4-XP cohort, relative risk of internal tumors was 34 (95% confidence interval (CI) 25–47) times higher than in the general population (p-value = 1.0E−47) and tumor arose 50 years earlier. The XP-C group was at the highest risk for the 0–20 years old-patients (OR = 665; 95% CI 368–1200; p-value = 4.3E−30). The highest risks were observed for tumors of central nervous system (OR = 331; 95% CI 171–641; p-value = 2.4E−20), hematological malignancies (OR = 120; 95% CI 77–186; p-value = 3.7E−36), thyroid (OR = 74; 95% CI 31–179; p-value = 1.2E−8) and gynecological tumors (OR = 91; 95% CI 42–193; p-value = 3.5E−12). The type of mutation on the XPC gene is associated with different classes of internal tumors. The majority of French XP-C patients (80%) are originated from North Africa and carried the XPC delTG founder mutation specific from the South Mediterranean area. The OR is extremely high for young (0–20 years) patients with more than 1300-fold increase for the French XPs carrying the founder mutation.

Conclusion

Because the age of XP population is increasing due to better sun-protection and knowledge of the disease, these results are of particular importance for the physicians to help in early prevention and detection of internal tumors in their XP patients. Few preventive blood analyses or simple medical imaging may help to better detect early cancer appearance in this population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02203-1.

Revisiting the structural features of the xeroderma pigmentosum proteins: Focus on mutations and knowledge gaps

The nucleotide excision repair pathway is a broadly studied DNA repair mechanism because impairments of its key players, the xeroderma pigmentosum proteins (XPA to XPG), are associated with multiple hereditary diseases. Due to the massive number of novel mutations reported for these proteins and new structural data published every year, proper categorization and discussion of relevant observations is needed to organize this extensive inflow of knowledge. This review aims to revisit the structural data of all XP proteins while updating it with the information developed in of the past six years. Discussions and interpretations of mutation outcomes, mechanisms of action, and knowledge gaps regarding their structures are provided, as well as new perspectives based on recent research.

Xeroderma Pigmentosum: General Aspects and Management

Xeroderma Pigmentosum (XP) is a rare genetic syndrome with a defective DNA nucleotide excision repair. It is characterized by (i) an extreme sensitivity to ultraviolet (UV)-induced damages in the skin and eyes; (ii) high risk to develop multiple skin tumours; and (iii) neurologic alterations in the most severe form. To date, the management of XP patients consists of (i) early diagnosis; (ii) a long-life protection from ultraviolet radiation, including avoidance of unnecessary UV exposure, wearing UV blocking clothing, and use of topical sunscreens; and (iii) surgical resections of skin cancers. No curative treatment is available at present. Thus, in the last decade, in order to prevent or delay the progression of the clinical signs of XP, numerous strategies have been proposed and tested, in some cases, with adverse effects. The present review provides an overview of the molecular mechanisms featuring the development of XP and highlights both advantages and disadvantages of the clinical approaches developed throughout the years. The intention of the authors is to sensitize scientists to the crucial aspects of the pathology that could be differently targeted. In this context, the exploration of the process underlining the conception of liposomal nanocarriers is reported to focus the attention on the potentialities of liposomal technology to optimize the administration of chemoprotective agents in XP patients.

Identification of a novel protein truncating mutation p.Asp98* in XPC associated with xeroderma pigmentosum in a consanguineous Pakistani family

BACKGROUND

Xeroderma pigmentosum (XP) is a rare genetic disorder, which is characterized by hyper-sensitivity to solar ultraviolet (UV) radiation. Clinical consequences of sun exposure are skin lesions and an increased risk of developing skin cancer. Genetic studies have identified eight genes associated with xeroderma pigmentosum. The proteins encoded by these genes are mainly involved in DNA repair mechanisms.

METHODS

Molecular genetic characterization of patients with xeroderma pigmentosum involved positional cloning methods such as homozygosity mapping and subsequent candidate gene analysis. Mutation screening was performed through Sanger DNA sequencing.

RESULTS AND DISCUSSION

In this case study, we report a novel protein truncating mutation in XPC associated with autosomal recessive xeroderma pigmentosum in a consanguineous Pakistani family. Genetic mapping revealed a novel single base insertion of a thymine nucleotide NM_004628.4: c.291dupT (c.291_292insT) in the second exon of XPC. The identified mutation leads to a premature stop codon (TGA) at amino acid position 98 (p.Asp98*) and thus presumably results in a truncated protein. The Xeroderma pigmentosum, complementation group C (XPC) is located on 3p25.1 and encodes a protein involved in nucleotide excision repair. The identified mutation presumably truncates all functional domains of the XPC protein, which likely results in the loss of protein function.

CONCLUSION

The study expands the knowledge of the mutational spectrum of XPC and is valuable for genetic counseling of affected individuals and their families.

Unusual intraoral cancer with unexpected outcome in a patient with xeroderma pigmentosum: An alert for antineoplastic treatment

Xeroderma pigmentosum (XP) is a rare autosomal disorder characterized by extreme sensitivity to ultraviolet radiation. DNA repair mechanisms are impaired, and minimal sun exposure can lead to the development of cutaneous neoplasms in very young patients. Intraoral carcinomas are uncommon and, when present, are located mainly at the tongue tip. We report an unprecedented case of squamous cell carcinoma (SCC) in the floor of mouth of a 23-year-old woman with XP. The patient was referred to the oncologist, and 2 months after surgical resection, she underwent a single session of chemotherapy plus radiotherapy. However, she died 73 hours after undergoing her first chemotherapy session. Considering the unexpected outcome of this case, we also investigated possible exacerbated adverse effects of antineoplastic treatments (especially cisplatin-based chemotherapy) in patients with XP and reviewed the main characteristics of the disease, especially cases with oral manifestations reported in the literature.

Xeroderma Pigmentosum and Bone Marrow Aplasia: A Rare Association

Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder characterized by hypersensitivity to ultraviolet rays and predisposition to cutaneous malignancies. Hematological disorders associated with XP include myelodysplastic syndrome and acute leukemia. We report a 7-year-old child with XP along with squamous cell carcinoma and bone marrow aplasia.

Xpg limits the expansion of haematopoietic stem and progenitor cells after ionising radiation

Reduced capacity of genome maintenance represents a problem for any organism, potentially causing premature death, carcinogenesis, or accelerated ageing. Strikingly though, loss of certain genome stability factors can be beneficial, especially for the maintenance of tissue stem cells of the intestine and the haematopoietic system. We therefore screened for genome stability factors negatively impacting maintenance of haematopoietic stem cells (HSC) in the context of ionising radiation (IR). We found that in vivo knock down of Xeroderma pigmentosum, complementation group G (Xpg) causes elevation of HSC numbers after IR treatment, while numbers of haematopoietic progenitors are elevated to a lesser extent. IR rapidly induces Xpg both on mRNA and on protein level. Prevention of this induction does not influence activation of the checkpoint cascade, yet attenuates late checkpoint steps such as induction of p21 and Noxa. This causes a leaky cell cycle arrest and lower levels of apoptosis, both contributing to increased colony formation and transformation rates. Xpg thus helps to adequately induce DNA damage responses after IR, thereby keeping the expansion of damaged cells under control. This represents a new function of Xpg in the response to IR, in addition to its well-characterized role in nucleotide excision repair.

The Xpc gene markedly affects cell survival in mouse bone marrow

The XPC protein (encoded by the xeroderma pigmentosum Xpc gene) is a key DNA damage recognition factor that is required for global genomic nucleotide excision repair (G-NER). In contrast to transcription-coupled nucleotide excision repair (TC-NER), XPC and G-NER have been reported to contribute only modestly to cell survival after DNA damage. Previous studies were conducted using fibroblasts of human or mouse origin. Since the advent of Xpc-/- mice, no study has focused on the bone marrow of these mice. We used carboplatin to induce DNA damage in Xpc-/- and strain-matched wild-type mice. Using several independent methods, Xpc-/- bone marrow was approximately 10-fold more sensitive to carboplatin than the wild type. Importantly, 12/20 Xpc-/- mice died while 0/20 wild-type mice died. We conclude that G-NER, and XPC specifically, can contribute substantially to cell survival. The data are important in the context of cancer chemotherapy, where Xpc gene status and G-NER may be determinants of response to DNA-damaging agents including carboplatin. Additionally, altered cell cycles and altered DNA damage signalling may contribute to the cell survival end point.

Tissue-specific accelerated aging in nucleotide excision repair deficiency

Nucleotide excision repair (NER) is a multi-step DNA repair mechanism that removes helix-distorting modified nucleotides from the genome. NER is divided into two subpathways depending on the location of DNA damage in the genome and how it is first detected. Global genome NER identifies and repairs DNA lesions throughout the genome. This subpathway of NER primarily protects against the accumulation of mutations in the genome. Transcription-coupled (TC)-NER rapidly repairs lesions in the transcribed strand of DNA that block transcription by RNA polymerase II. TC-NER prevents cell death in response to stalled transcription. Defects in NER cause three distinct human diseases: xeroderma pigmentosum, Cockayne syndrome and trichothiodystrophy. Each of these syndromes is characterized by premature onset of pathologies that overlap with those associated with old age in humans. This reveals the contribution of DNA damage to multiple age-related diseases. Tissues affected include the skin, eye, bone marrow, nervous system and endocrine axis. This review emphasizes accelerated aging associated with xeroderma pigmentosum and discusses the cause of these pathologies, either mutation accumulation or cell death as a consequence of failure to repair DNA damage.

DNA repair is crucial for maintaining hematopoietic stem cell function

Richard Cornall and collaborators recently developed a mouse model of Ligase IV syndrome with growth retardation and immunodeficiency due to a defect in nonhomologous end-joining (NHEJ) of DNA double-strand breaks. They demonstrated age-dependent loss of hematopoietic stem cell function in these mice. Simultaneously, Irving Weissman and colleagues demonstrated a similar phenomenon in Ku80(-/-) mice defective in NHEJ and telomere maintenance, Xpd(TTD) mice defective in nucleotide excision repair, and late generation mTr(-/-) missing telomerase activity. These studies strongly support the hypothesis that genomic stress causes aging by limiting the ability of stem cells to indefinitely maintain tissue homeostasis.

Clinical and cellular ionizing radiation sensitivity in a patient with xeroderma pigmentosum

XP14BR is a cell line derived from a xeroderma pigmentosum (XP) patient from complementation group C. The patient was unusual in presenting with an angiosarcoma of the scalp, treated by surgical excision and radiotherapy. Following 38 Gy in 19 fractions with 6 MEV electrons, a severe desquamation and necrosis of the underlying bone ensued, and death followed 4 years later. The cell line was correspondingly hypersensitive to the lethal effects of gamma irradiation. We had previously shown that this sensitivity could be discriminated from that seen in ataxia-telangiectasia (A-T). The cellular response to ultraviolet radiation below 280 nm (UVC) was characteristic of XP cells, indicating the second instance, in our experience, of dual cellular UVC and ionizing radiation hypersensitivity in XP. We then set out to evaluate any defects in repair of ionizing radiation damage and to verify any direct contribution of the XPC gene. The cells were defective in repair of a fraction of double strand breaks, with a pattern reminiscent of A-T. The cell line was immortalized with the vector pSV3neo and the XPC cDNA transfected in to correct the defect. The progeny derived from this transfection showed the presence of the XPC gene product, as measured by immunoblotting. A considerable restoration of normal UVC, but not ionizing radiation, sensitivity was observed amongst the clones. This differential correction of cellular sensitivity is strong evidence for the presence of a defective radiosensitivity gene, distinct from XPC, which is responsible for the clinical hypersensitivity to ionizing radiation. It is important to resolve how widespread ionizing radiation sensitivity is amongst XP patients.

Four radiation hypersensitivity cases and their implications for clinical radiotherapy

BACKGROUND AND PURPOSE

Over a 20 year period, four out of 2000 paediatric radiotherapy patients, treated at St. Bartholomew's Hospital (three with lymphoma, one with angiosarcoma), have revealed extreme/fatal clinical hypersensitivity in normal tissues.

PATIENTS AND METHODS

Cellular hypersensitivity was confirmed in vitro and attributed to the ataxia-telangiectasia (A-T) gene in cases I and II, a newly described defect in the DNA ligase 4 gene in case III, and a novel and as yet incompletely defined, molecular defect in case IV who presented with xeroderma pigmentosum (XP).

RESULTS

The severe clinical hypersensitivity preceded the cellular and molecular analysis, but did not manifest as a clinically exaggerated normal tissue reaction until 3+ weeks after the start of a conventionally fractionated course of radiotherapy, by which time the latent damage had been inflicted. There were no clinical stigmata to alert the clinician to a predisposing syndrome in two patients (cases I and II). We point out that approximately 20% of A-T patients are classified as variants with delayed expression of clinical symptoms, and case II falls into this category.

CONCLUSIONS

As lymphoma (incidence, one in 100000 children) constituted the majority of the diagnoses, questions arise as to: (1), the probability of other centres having experienced and being presented in the future with similar problems (particularly bearing in mind that other oncologically predisposing radiosensitivity syndromes have not been not represented in our experience); and (2), the appropriateness, efficiency and applicability of predictive assays. Unambiguous cellular radiosensitivity would have been apparent from clonal assays on fibroblast cultures from all four cases prior to treatment, but such assays take 4-6 weeks to produce results. While estimates of chromosome damage or clonal assays on pre-treatment blood derived cells would be faster, there is a health economics issue as to the general applicability of such 'screening' assays.

Xeroderma pigmentosum with adult Wilms' tumour. A rare association

Xeroderma pigmentosum is an uncommon skin disorder associated with increased incidence of skin tumours and, less often, internal malignancies. Wilms' tumour is a common paediatric tumour, observed rarely in adults. Here we report the rare association of Xeroderma pigmentosum with adult Wilms' tumour in two Libyan females. To the best of our knowledge, this association has not been reported so far in the literature.

Use of fluorescence in situ hybridization to determine the relationship between chromosome aberrations and cell survival in eight human fibroblast strains

A predictive assay of normal tissue radiosensitivity could benefit 'treatment tailoring' of radiotherapy for certain categories of tumour. The use of present clonogenic cell survival assays for this purpose would be impractical in routine clinical practice because of the lengthy assay time. Fluorescence in situ hybridization (FISH) using whole chromosome probes on metaphases was investigated as a potential substitute. Eight human fibroblast cell strains with a range of radiosensitivities were tested. For each strain, cell survival curves were determined and correlated with chromosome aberrations detected by FISH performed on metaphase cells collected 52 h after irradiation. A whole chromosome probe for chromosome 4 was used for all cell strains. The results revealed an increase in the percentage of metaphases with aberrant chromosomes (translocations and/or breaks) with increasing radiation dose for all strains. For the more radiosensitive cell strains there were relatively more aberrant metaphases for a given radiation dose when compared with fibroblasts from a normal donor. The relationship between surviving fraction and chromosome aberrations showed some variation between strains, but a linear regression for all data showed a highly statistically significant correlation (r = 0.89, p < 0.0005). These results suggest that an assay of chromosome damage using FISH could substitute for the clonogenic assay to predict the radiation sensitivity of human fibroblasts.