Neurological disease in xeroderma pigmentosum: prospective cohort study of its features and progression.

Xeroderma pigmentosum (XP) results from biallelic mutations in any of eight genes involved in DNA repair systems, thus defining eight different genotypes (XPA, XPB, XPC, XPD, XPE, XPF, XPG and XP variant or XPV). In addition to cutaneous and ophthalmological features, some patients present with XP neurological disease. It is unknown whether the different neurological signs and their progression differ among groups. Therefore, we aim to characterize the XP neurological disease and its evolution in the heterogeneous UK XP cohort. Patients with XP were followed in the UK National XP Service, from 2009 to 2021. Age of onset for different events was recorded. Cerebellar ataxia and additional neurological signs and symptoms were rated with the Scale for the Assessment and Rating of Ataxia (SARA), the Inventory of Non-Ataxia Signs (INAS) and the Activities of Daily Living questionnaire (ADL). Patients' mutations received scores based on their predicted effects. Data from available ancillary tests were collected. Ninety-three XP patients were recruited. Thirty-six (38.7%) reported neurological symptoms, especially in the XPA, XPD and XPG groups, with early-onset and late-onset forms, and typically appearing after cutaneous and ophthalmological symptoms. XPA, XPD and XPG patients showed higher SARA scores compared to XPC, XPE and XPV. SARA total scores significantly increased over time in XPD (0.91 points/year, 95% confidence interval: 0.61, 1.21) and XPA (0.63 points/year, 95% confidence interval: 0.38, 0.89). Hyporeflexia, hypopallesthaesia, upper motor neuron signs, chorea, dystonia, oculomotor signs and cognitive impairment were frequent findings in XPA, XPD and XPG. Cerebellar and global brain atrophy, axonal sensory and sensorimotor neuropathies, and sensorineural hearing loss were common findings in patients. Some XPC, XPE and XPV cases presented with abnormalities on examination and/or ancillary tests, suggesting underlying neurological involvement. More severe mutations were associated with a faster progression in SARA total score in XPA (0.40 points/year per 1-unit increase in severity score) and XPD (0.60 points/year per 1-unit increase), and in ADL total score in XPA (0.35 points/year per 1-unit increase). Symptomatic and asymptomatic forms of neurological disease are frequent in XP patients, and neurological symptoms can be an important cause of disability. Typically, the neurological disease will be preceded by cutaneous and ophthalmological features, and these should be actively searched in patients with idiopathic late-onset neurological syndromes. Scales assessing cerebellar function, especially walking and speech, and disability can show progression in some of the groups. Mutation severity can be used as a prognostic biomarker for stratification purposes in clinical trials.

Pathogenesis of solar urticaria: Classic perspectives and emerging concepts.

Solar urticaria is a rare, immunologically mediated photodermatosis in which activation of cutaneous mast cells is triggered by specific wavelengths of solar electromagnetic radiation. This manifests clinically as the rapid development of cutaneous itch, erythema and wheal formation after several minutes of sun exposure. Disease mechanisms in solar urticaria remain incompletely elucidated and there have been few recent investigations of its pathobiology. Historic passive transfer experiments performed during the twentieth century provide support for a 'photoallergy' model of disease pathogenesis, wherein molecular alteration of a putative chromophore by solar electromagnetic radiation produces mast cell activation via an IgE-dependent mechanism. However, this model does not account for several observations made during passive transfer experiments nor does it explain a range of subsequent clinical and photobiological observations made in solar urticaria patients. Furthermore, increased understanding of the molecular dynamics underpinning cutaneous mast cell responses highlights the need to reformulate our understanding of solar urticaria pathogenesis in the context of this contemporary scientific landscape. In this review, we discuss the current understanding of solar urticaria pathogenesis and, by incorporating recent scientific and clinical observations, develop new hypotheses to drive future investigation into this intriguing disorder.

Pediatric Autoimmune Bullous Disease: A Literature Review and Update on Management.

Pediatric autoimmune bullous disease is a rare group of blistering skin disorders in children that result from autoimmunity against intercellular and basement membrane antigens in the skin and mucous membranes. Most pediatric cases are treated with oral corticosteroids or longer-term immunosuppressants such as azathioprine or mycophenolate mofetil. Immunomodulating drugs such as rituximab are increasingly being considered as options for refractory disease.

Hydroa vacciniforme-like lymphoproliferative disorder: an EBV disease with a low risk of systemic illness in whites.

Patients with classic hydroa vacciniforme-like lymphoproliferative disorder (HVLPD) typically have high levels of Epstein-Barr virus (EBV) DNA in T cells and/or natural killer (NK) cells in blood and skin lesions induced by sun exposure that are infiltrated with EBV-infected lymphocytes. HVLPD is very rare in the United States and Europe but more common in Asia and South America. The disease can progress to a systemic form that may result in fatal lymphoma. We report our 11-year experience with 16 HVLPD patients from the United States and England and found that whites were less likely to develop systemic EBV disease (1/10) than nonwhites (5/6). All (10/10) of the white patients were generally in good health at last follow-up, while two-thirds (4/6) of the nonwhite patients required hematopoietic stem cell transplantation. Nonwhite patients had later age of onset of HVLPD than white patients (median age, 8 vs 5 years) and higher levels of EBV DNA (median, 1 515 000 vs 250 000 copies/ml) and more often had low numbers of NK cells (83% vs 50% of patients) and T-cell clones in the blood (83% vs 30% of patients). RNA-sequencing analysis of an HVLPD skin lesion in a white patient compared with his normal skin showed increased expression of interferon-γ and chemokines that attract T cells and NK cells. Thus, white patients with HVLPD were less likely to have systemic disease with EBV and had a much better prognosis than nonwhite patients. This trial was registered at www.clinicaltrials.gov as #NCT00369421 and #NCT00032513.

Deep phenotyping of 89 xeroderma pigmentosum patients reveals unexpected heterogeneity dependent on the precise molecular defect.

Xeroderma pigmentosum (XP) is a rare DNA repair disorder characterized by increased susceptibility to UV radiation (UVR)-induced skin pigmentation, skin cancers, ocular surface disease, and, in some patients, sunburn and neurological degeneration. Genetically, it is assigned to eight complementation groups (XP-A to -G and variant). For the last 5 y, the UK national multidisciplinary XP service has provided follow-up for 89 XP patients, representing most of the XP patients in the United Kingdom. Causative mutations, DNA repair levels, and more than 60 clinical variables relating to dermatology, ophthalmology, and neurology have been measured, using scoring systems to categorize disease severity. This deep phenotyping has revealed unanticipated heterogeneity of clinical features, between and within complementation groups. Skin cancer is most common in XP-C, XP-E, and XP-V patients, previously considered to be the milder groups based on cellular analyses. These patients have normal sunburn reactions and are therefore diagnosed later and are less likely to adhere to UVR protection. XP-C patients are specifically hypersensitive to ocular damage, and XP-F and XP-G patients appear to be much less susceptible to skin cancer than other XP groups. Within XP groups, different mutations confer susceptibility or resistance to neurological damage. Our findings on this large cohort of XP patients under long-term follow-up reveal that XP is more heterogeneous than has previously been appreciated. Our data now enable provision of personalized prognostic information and management advice for each XP patient, as well as providing new insights into the functions of the XP proteins.

Malfunction of nuclease ERCC1-XPF results in diverse clinical manifestations and causes Cockayne syndrome, xeroderma pigmentosum, and Fanconi anemia.

Cockayne syndrome (CS) is a genetic disorder characterized by developmental abnormalities and photodermatosis resulting from the lack of transcription-coupled nucleotide excision repair, which is responsible for the removal of photodamage from actively transcribed genes. To date, all identified causative mutations for CS have been in the two known CS-associated genes, ERCC8 (CSA) and ERCC6 (CSB). For the rare combined xeroderma pigmentosum (XP) and CS phenotype, all identified mutations are in three of the XP-associated genes, ERCC3 (XPB), ERCC2 (XPD), and ERCC5 (XPG). In a previous report, we identified several CS cases who did not have mutations in any of these genes. In this paper, we describe three CS individuals deficient in ERCC1 or ERCC4 (XPF). Remarkably, one of these individuals with XP complementation group F (XP-F) had clinical features of three different DNA-repair disorders--CS, XP, and Fanconi anemia (FA). Our results, together with those from Bogliolo et al., who describe XPF alterations resulting in FA alone, indicate a multifunctional role for XPF.

Primary and secondary intralymphatic histiocytosis.

BACKGROUND: Intralymphatic histiocytosis (IH) is a rare condition often associated with systemic disease. A benign condition, clinical presentations can vary greatly and its cause is largely unknown. Histologically, there are macrophages within distended lymphatic vessels, although this can be an incidental finding or the primary abnormality. OBJECTIVE: We present a series of 7 cases of IH with and without disease associations, and a review of the literature. We propose IH as either primary (without associated conditions) or secondary (associated with systemic disease). METHODS: This was a retrospective collection of patients whose skin biopsy specimens revealed intralymphatic collections of histiocytes. We reviewed their clinical presentation, disease associations, and staining of slides with CD68 in all cases, D2-40 in 5 cases, and HLA-DR in 4 cases. RESULTS: Clinical features were highly variable, and not all cases were associated with systemic disease. One case had admixed reactive angioendotheliomatosis. All 4 cases stained for HLA-DR showed strong expression by the intralymphatic macrophages. LIMITATIONS: Retrospective analysis and limited numbers are limitations. CONCLUSION: IH is not always associated with systemic disease although macrophage activation nevertheless implies immune activation.

Successful serial plasmapheresis for solar urticaria, a case report and literature review.

BACKGROUND/PURPOSE: Amidst the emergence of new therapeutic options, traditional therapeutic plasmapheresis (TPE) used in diseases involving a toxic substance in the plasma, remains a viable alternative for cases of recalcitrant solar urticaria (SU). We emphasize the importance of documenting successful experience with repeated plasmapheresis to increase awareness amongst physicians and dermatologists regarding this effective treatment option. MATERIAL AND METHOD: We reported a case of recalcitrant SU that had not responded to a combination of H1-antihistamines, immunosuppressants, omalizumab and intravenous immunoglobulin. We introduced serial TPE, which involved two consecutive days of procedures for each course was introduced. We detailed the regimen and highlighted the clinical and objective benefits observed with multiple treatments. Additionally, we compared this to other plasmapheresis regimens and their treatment responses previously reported for solar urticaria. RESULTS: Our patient underwent serial TPE, totaling 42 procedures over five years. Following the last TPE session, phototesting showed a sustained prolongation of minimal urticating doses (MUDS), which exceeded the maximum tested doses across nearly all ultraviolet (UV) and visible light ranges, with the exception of the two short ultraviolet B (UVB) wavelengths. MUDs increased to 25 from 6 mj/cm2 at 307.5± 5nm, and to 500 from 15 mj/cm2 at 320 ± 10nm, before the initial TPE. In our review, we included five articles covering eight SU patients who received TPE. Of these, the five patients with positive intradermal tests responded particularly well immediately after treatment. However, the condition relapsed within two weeks in one patient and within two months in another. In contrast, the other three patients with negative intradermal tests, showed no significant benefits from the treatment. No serious side effects from TPE were reported amongst the patients. CONCLUSIONS: This review underscores the efficacy of serial plasmapheresis procedures in treating refractory cases of SU, high3lighting the robust results observed.

Insights from multi-omic modeling of neurodegeneration in xeroderma pigmentosum using an induced pluripotent stem cell system.

Xeroderma pigmentosum (XP) is caused by defective nucleotide excision repair of DNA damage. This results in hypersensitivity to ultraviolet light and increased skin cancer risk, as sunlight-induced photoproducts remain unrepaired. However, many XP patients also display early-onset neurodegeneration, which leads to premature death. The mechanism of neurodegeneration is unknown. Here, we investigate XP neurodegeneration using pluripotent stem cells derived from XP patients and healthy relatives, performing functional multi-omics on samples during neuronal differentiation. We show substantially increased levels of 5',8-cyclopurine and 8-oxopurine in XP neuronal DNA secondary to marked oxidative stress. Furthermore, we find that the endoplasmic reticulum stress response is upregulated and reversal of the mutant genotype is associated with phenotypic rescue. Critically, XP neurons exhibit inappropriate downregulation of the protein clearance ubiquitin-proteasome system (UPS). Chemical enhancement of UPS activity in XP neuronal models improves phenotypes, albeit inadequately. Although more work is required, this study presents insights with intervention potential.

Spotlight on 'xeroderma pigmentosum'.

Xeroderma pigmentosum (XP) is a rare autosomal recessive disorder of DNA repair characterised by photosensitivity, progressive pigmentary change, and an increased incidence of ultraviolet (UV)-induced skin and mucous membrane cancers. Approximately 25% of XP patients also have progressive neurological degeneration. There are eight XP complementation groups (XP-A through to XP-G, and XP variant (XP-V)), corresponding to the affected DNA repair gene. Seven of these genes, XPA to XPG, are involved in nucleotide excision repair, removing UV-induced damage from DNA. The eighth gene, XPV (or POLH), encodes for DNA polymerase η, which is required for the replication of DNA containing unrepaired UV-induced damage. There is wide variability in clinical features both between and within XP complementation groups. The diagnosis is made clinically and confirmed by cellular tests for defective DNA repair. This is followed by identification of the defective gene (complementation analysis) and causative mutation(s). Although there is no cure, sun avoidance and regular follow-up to assess and treat any skin cancers increase life expectancy. The neurological abnormalities are progressive and result in a shortened lifespan. The study of patients with XP has highlighted the importance of nucleotide excision repair in the aetiology of skin cancers and neurological degeneration, and has solidified the link between UV exposure, DNA damage, somatic mutations and skin cancer.

Retrospective study of efficacy and adverse events of immune checkpoint inhibitors in 22 xeroderma pigmentosum patients with metastatic or unresectable cancers.

Background: Xeroderma pigmentosum (XP), a rare disease with defects in DNA repair genes, has >1,000-fold increased risk of ultraviolet-induced skin cancers. Immune checkpoint inhibitors (ICIs) are used for treating cancers with large numbers of mutations but may also promote adverse events (AEs). Deficient DNA repair in XP patients may lead to increased numbers of mutations, leading to enhanced efficacy of cancer response or, alternatively, to increased AE in response to ICI. We sought to compare the efficacy and AE of ICI in XP patients with metastatic or unresectable cancers to that of ICI-treated patients in the general population. Methods: In this retrospective study, we reviewed medical records of XP patients treated in the United States and in London (UK). We also reviewed published reports of ICI-treated XP patients and patients in the general population. Results: Metastatic or unresectable cancers in all 22 (100%) XP patients showed regression or remission in response to ICI. The types and frequencies of AE in XP patients were similar to those reported among ICI-treated patients in the general population. However, two XP patients had concurrent additional cancers that did not respond to ICI, two XP patients had cancer recurrence or progression after initial response, and eight XP patients developed new skin cancers during or after ICI treatment. Conclusion: In this retrospective study with small sample size, XP patients demonstrated positive responses to ICI and the treatment was well tolerated but some patients developed new skin cancers while being treated. ICIs can be considered in treating metastatic or unresectable cancers in XP patients.