The present status of xeroderma pigmentosum in Japan and a tentative severity classification scale

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.

Clinical trial on the efficacy and safety of NPC-15 for patients with xeroderma pigmentosum exaggerated sunburn reaction type: XP-1 study protocol for a multicentre, double-blinded, placebo-controlled, two-group crossover study followed by a long-term open study in Japan

INTRODUCTION

Xeroderma pigmentosum (XP) is a rare intractable disease without a fundamental treatment, presenting with severe photosensitivity, freckle-like pigmented and depigmented maculae and numerous skin cancers before the age of 10 years without strict sun protection. About 70% of the patients exhibit extremely severe sunburn reactions and most of them develop neurological symptoms, including sensorineural hearing impairment and progressive peripheral and central nervous disorders beginning from childhood ages. In the preclinical study, we found that N-acetyl-5-methoxytryptamine was effective in suppressing skin tumour development in addition to improvement of auditory brainstem response in chronically ultraviolet-irradiated XP-A model mice.

METHODS AND ANALYSIS

On the bases of the preclinical study, we conduct a clinical trial on the efficacy of NPC-15 for patients with XP with exaggerated sunburn reaction type by a multicentre, double-blinded placebo-controlled, two-group crossover study followed by a 52 weeks open study.

ETHICS AND DISSEMINATION

Ethics approval is overseen by the Kobe University Institutional Review Board and Osaka Medical and Pharmaceutical University Institutional Review Board, and the study is conducted in accordance with the approved protocol. All participants will be required to provide written informed consent. Findings will be disseminated through scientific and professional conferences and peer-reviewed journal publications. The data sets generated during the study will be available from the corresponding author on reasonable request.

TRIAL REGISTRATION NUMBER

jRCTs051210181.

Skin tumors in xeroderma pigmentosum: Evaluation of a large series and a literature review

BACKGROUND

Xeroderma pigmentosum (XP) is a rare genodermatosis with a lifelong propensity to develop malignant skin tumors.

METHODS

In this retrospective study, 24 XP patients were evaluated with regard to frequency and clinicopathological features of benign and malignant skin tumors.

RESULTS

Seventeen patients had at least one malignant skin tumor diagnosed: basal cell carcinoma (BCC) in 13 patients (n = 72), basosquamous carcinoma in three patients (n = 4), squamous cell carcinoma in six patients (n = 13), keratoacanthoma in three patients (n = 15), and melanoma in six patients (n = 18). Most melanomas (n = 15) were in situ lesions. Several benign skin tumors were noted such as tricholemmoma (n = 1), trichoepithelioma (n = 1), trichoblastoma (n = 1), follicular infundibulum tumor (n = 1), keratoacanthoma-like follicular lesion (n = 1), adnexal tumors with folliculosebaceous (n = 1) and tricholemmal differentiation (n = 1), and neurofibroma (n = 1). Benign vascular proliferations including pyogenic granulomas (n = 8), widespread telangiectasias, and senile angioma-like lesions were also observed in 3, 5, and 5 patients, respectively.

CONCLUSIONS

Similar to many reports, BCC was found to be the most common malignant skin tumor. The high prevalence of benign adnexal tumors of follicular differentiation, some of them showing mixed histopathological features and various vascular proliferations in our series raises the question of whether they indicate a formerly undescribed association with XP.

Progressive length-dependent polyneuropathy in xeroderma pigmentosum group A

BACKGROUND

In this study, we aimed to investigate the progression of peripheral nervous system involvement in xeroderma pigmentosum group A (XP-A).

METHODS

We performed nerve conduction studies in 17 genetically confirmed XP-A patients and conducted follow-ups. Of these patients we also analyzed gray matter volume (GMV) using brain MRI and assessed the severity score of clinical and skin manifestation.

RESULTS

We found significant reduction in the motor and sensory nerve action potential amplitude and mild reduction in conduction velocity. These findings were predominant in sensory nerves and the lower limbs, were observed since early childhood, and gradually deteriorated with age.

CONCLUSIONS

The electrophysiological characteristics of XP-A patients are consistent with length-dependent axonal polyneuropathy and there is progressive deterioration from early childhood.

Xeroderma Pigmentosum: Ocular Findings in an Isolated Brazilian Group with an Identified Genetic Cluster

Purpose

Xeroderma pigmentosum (XP) is a rare autosomal recessive genetic 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. Eight different genes are affected, and the prevalence of the disease differs across the world. The present study describes the main ophthalmologic features and symptoms in patients with XP in this case series.

Methods

Patients were examined consecutively at the University Hospital of the Federal University of Goias between January 2016 and June 2018. All patients underwent ophthalmologic examination and were asked about their ophthalmological history and the presence of ocular symptoms.

Results

Twenty-one patients with genetic confirmation were evaluated. The genetic variants XPV and XPC were detected in the patients. The most prevalent findings include eyelid changes, observed in 80.9% of the patients, and ocular surface changes as punctate keratopathy, occurring in 16 patients (76.2%), corneal neovascularization, and corneal opacities. Six patients (28.5%) presented corneoconjunctival tumor. More than half of patients had previous history of treatment of ocular neoplasia. Ocular burning was the most reported symptom.

Conclusions

The ocular characteristics identified in this study corroborate the existing literature, mainly related to the surface. Concerning the XP variant and the gravity of ocular signs, XPC has earlier and more severe symptoms than XPV. Due to their relative rarity, publications of XP cases are important to understand the possible damages caused by the disease in the eyes and surrounding area.

Frequent retrotransposition of endogenous genes in ERCC2-deficient cells derived from a patient with xeroderma pigmentosum

BACKGROUND

Retrotransposition of protein-coding genes is thought to occur due to the existence of numerous processed pseudogenes in both animals and plants. Unlike retrotransposons including Alu and LINE-1, direct evidence of such retrotransposition events has not been reported to date. Even if such an event occurs in a somatic cell, it is almost impossible to detect it using bulk of cells as a sample. Single-cell analyses or other techniques are needed.

METHODS

In order to examine genetic stability of stem cells, we have established induced pluripotent stem cell (iPSC) lines from several patients with DNA repair-deficiency disorders, such as ataxia telangiectasia and xeroderma pigmentosum, along with healthy controls. Performing whole-exome sequencing analyses of these parental and iPSC lines, we compiled somatic mutations accumulated by the deficiency of DNA repair mechanisms. Whereas most somatic mutations cannot be detected in bulk, cell reprogramming enabled us to observe all the somatic mutations which had occurred in the cell line. Patterns of somatic mutations should be distinctive depending on which DNA repair gene is impaired.

RESULTS

The comparison revealed that deficiency of ATM and XPA preferentially gives rise to indels and single-nucleotide substitutions, respectively. On the other hand, deficiency of ERCC2 caused not only single-nucleotide mutations but also many retrotranspositions of endogenous genes, which were readily identified by examining removal of introns in whole-exome sequencing. Although the number was limited, those events were also detected in healthy control samples.

CONCLUSIONS

The present study exploits clonality of iPSCs to unveil somatic mutation sets that are usually hidden in bulk cell analysis. Whole-exome sequencing analysis facilitated the detection of retrotransposition mutations. The results suggest that retrotranspositions of human endogenous genes are more frequent than expected in somatic cells and that ERCC2 plays a defensive role against transposition of endogenous and exogenous DNA fragments.

Ocular and Periocular Tumors in Xeroderma Pigmentosum: A Study of 120 Asian Indian Patients

PURPOSE

We studied the incidence, treatment, and outcome of ocular and periocular tumors in patients with xeroderma pigmentosum (XP).

DESIGN

Retrospective case series.

METHODS

This single-institution study included 120 patients with XP who underwent intervention with excisional biopsy, enucleation, or orbital exenteration. The primary outcome measures were the occurrence of eyelid or ocular surface tumor, globe salvage, locoregional and systemic metastasis, and death.

RESULTS

The mean age at presentation was 19 years. A family history of XP was present in 32 (27%) patients. Over a mean follow-up of 61 months, 34 (28%) patients developed no ocular/adnexal tumor, 86 (72%) developed ocular surface malignancy, 15 (13%) developed eyelid malignancy, and 22 (18%) developed other head and neck malignancies. Of the 86 patients with ocular surface malignancy, 48 (56%) had unilateral tumor and 38 (44%) had bilateral tumors. Invasive squamous cell carcinoma (n = 51, 41%) was the most common ocular surface tumor. Of the 15 patients with eyelid tumors, 14 (93%) had unilateral tumor and 1 (7%) had bilateral involvement. Basal cell carcinoma (n = 8, 50%) was the most common eyelid tumor. There were events of ocular surface tumor recurrence (n = 55 eyes, 44%), eyelid tumor recurrence (n = 5 eyes, 31%), locoregional lymph node metastasis (n = 3, 2%), systemic metastasis (n = 1, 1%), and death (n = 1, 1%). Overall, globe salvage was achieved in 119 (99%) patients (both eyes were salvaged in 92 [76%] patients and at least 1 eye was salvaged in 27 [23%] patients).

CONCLUSION

XP is frequently associated with ocular surface, eyelid, and other head and neck malignancies. Lifelong follow-up is mandatory in these patients.

Characteristics of Xeroderma Pigmentosum in Japan: Lessons From Two Clinical Surveys and Measures for Patient Care

Xeroderma pigmentosum (XP) is a rare autosomal recessive hereditary disease caused by deficiency in repair of DNA lesions generated by ultraviolet radiation and other compounds. Patients with XP display pigmentary change and numerous skin cancers in sun-exposed sites, and some patients show exaggerated severe sunburns even upon minimum sun exposure as well as neurological symptoms. We conducted a nationwide survey for XP since 1980. In Japan, the frequency of the XP complementation group A is the highest, followed by the variant type; while in the Western countries, those of groups C or D are the highest. Regarding skin cancers in XP, basal cell carcinoma was the most frequent cancer that afflicted patients with XP, followed by squamous cell carcinoma, and malignant melanoma. The frequency of these skin cancers in patients with XP has decreased in these 20 years, and the age of onset of developing skin cancers is higher than those previously observed, owing to early diagnosis and education to patients and care takers on strict prevention from sunlight for patients with XP. On the other hand, the effective therapy for neurological XP has not been established yet, and this needs to be done urgently.