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.

Tricyclic antidepressant-induced photosensitivity; A case report and systematic review

BACKGROUND/PURPOSE

Tricyclic antidepressants (TCAs) are still widely used and are available to purchase without prescription in some countries. Awareness of adverse cutaneous drug reactions is essential.

METHOD

We reported a case of photo-distributed hyperpigmentation due to imipramine and carried out a systematic search of the related articles using the search terms "tricyclic antidepressants" or "tricyclic antidepressive agents", and "hyperpigmentation" or "photosensitivity disorder". Fifty non-duplicate citations were identified of which 28 articles which were independently assessed in full. The review was registered in PROSPERO, CRD42018107338.

RESULTS

The remaining 25 articles met our inclusion criteria. Photo-distributed hyperpigmentation tricyclic antidepressant-induced photosensitivity reactions (TIPs) was the most common presentation. In 21 cases, this presented as an asymptomatic discolouration of exposed sites. Imipramine (81%), amitriptyline (9.5%), desipramine hydrochloride (4.8%) and mirtazapine (4.8%) were reported to be the culprit drugs. Nineteen were female with a mean age at presentation of 55 years. Mean duration from commencing the culprit drug until the development of discolouration was 10.4 years. Mean daily dose was 222.7 mg for imipramine. Histology was characteristic with golden-brown or brownish granules deposited in dermis. Staining for Masson-Fontana and MEL-5 was positive in all cases. Phototesting had not been done in cases prior to ours (negative 3 months after discontinuation of imipramine). Three further reports of suspected TIP presented with non-specific and eczematous eruption. The two presentations were reported along with systemic problems (thrombocytopenia and hepatic injury).

CONCLUSIONS

This systematic review highlights the characteristic features of exposed site hyperpigmentation of TCA-induced photosensitivity occurring after prolonged drug exposure in many cases.

A new visible light absorbing organic filter offers superior protection against pigmentation by wavelengths at the UVR-visible boundary region

Skin pigmentation by solar ultraviolet radiation (UVR; ~295-400 nm) is well established. More recently, visible light (VL; 400-740 nm) has been shown to induce rapid pigmentation. Such pigmentation is thought to be caused by oxidative stress, which has associations with skin cancer and photoageing. However, the UVR-VL boundary region has been less well studied. The lower back of healthy Fitzpatrick skin type II-IV individuals was irradiated with increasing doses of narrow-band 385 nm and 405 nm radiation. Pigmentation change was measured immediately, 6 h and 24 h post-irradiation using two reflectance spectroscopy devices and visual grading. Pigmentation was dose-dependently increased in all skin types and time points for both spectra. Two sunscreens, both labelled SPF 15 and UVA protective in the EU and USA (but with different Boots star rating in the UK, 2* vs 5*) were compared. Their formulations were the same apart from the addition of a new organic filter bis-(diethylaminohydroxybenzoyl benzoyl) piperazine (BDBP) that absorbs between 350 and 425 nm. The product that lacked BDBP provided minimal protection against pigmentation, but its addition provided almost complete protection. This demonstrates the needs to improve photoprotection at the UVR-visible border and for sunscreens to act as neutral density filters.

Ultraviolet exposure to the face in patients with xeroderma pigmentosum and healthy controls: applying a novel methodology to define photoprotection behaviour

BACKGROUND

In Xeroderma Pigmentosum (XP), the main means of preventing skin and eye cancers is extreme protection against ultraviolet radiation (UVR). Protection is most important for the face.

OBJECTIVES

We aimed to assess how well patients with XP adhere to medical advice to protect against UVR by objectively estimating the mean daily dose of UVR to the face.

METHODS

We objectively estimated the UVR dose to the face in 36 XP patients and 25 healthy individuals over 3 weeks in the summer. We used a new methodology which combined UVR dose measurements from a wrist-worn dosimeter with an activity diary record of face photoprotection behaviour for each 15 minute period spent outside. A protection factor was associated with each behaviour, and the data analysed using a negative binomial mixed-effects model.

RESULTS

The mean daily UVR dose (weighted for DNA damage capacity) to the face in the XP patients was 0.13 Standard Erythemal Doses (SED) (mean in healthy individuals = 0.51 SED). There was wide variation between patients (range <0.01 - 0.48 SED/day). Self-caring adult patients had a very similar UV dose to the face to cared-for patients (0.13 vs 0.12 SED/day) despite photoprotecting much more poorly when outside, because the self-caring adults were outside in daylight much less.

CONCLUSIONS

Photoprotection behaviour varies widely within the XP group indicating that non-adherence to photoprotection advice is a significant issue. Timing and duration of going outside are as important as photoprotective measures taken when outside, to determine the UVR exposure to the face. This new methodology will be of value in identifying the sources of UVR exposure in other conditions where facial UV exposure is a key outcome, particularly in patients with multiple non-melanoma skin cancers.

Xeroderma pigmentosum: overview of pharmacology and novel therapeutic strategies for neurological symptoms

Xeroderma pigmentosum (XP) encompasses a group of rare diseases characterized in most cases by malfunction of nucleotide excision repair (NER), which results in an increased sensitivity to UV radiation in affected individuals. Approximately 25-30% of XP patients present with neurological symptoms, such as sensorineural deafness, mental deterioration and ataxia. Although it is known that dysfunctional DNA repair is the primary pathogenesis in XP, growing evidence suggests that mitochondrial pathophysiology may also occur. This appears to be secondary to dysfunctional NER but may contribute to the neurodegenerative process in these patients. The available pharmacological treatments in XP mostly target the dermal manifestations of the disease. In the present review, we outline how current understanding of the pathophysiology of XP could be used to develop novel therapies to counteract the neurological symptoms. Moreover, the coexistence of cancer and neurodegeneration present in XP led us to focus on possible new avenues targeting mitochondrial pathophysiology. LINKED ARTICLES: This article is part of a themed section on Mitochondrial Pharmacology: Featured Mechanisms and Approaches for Therapy Translation. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.22/issuetoc.

The UV/Visible Radiation Boundary Region (385-405 nm) Damages Skin Cells and Induces "dark" Cyclobutane Pyrimidine Dimers in Human Skin in vivo

The adverse effects of terrestrial solar ultraviolet radiation (UVR) (~295–400 nm) on the skin are well documented, especially in the UVB region (~295–320 nm). The effects of very long-wave UVA (>380 nm) and visible radiation (≥400 nm) are much less known. Sunscreens have been beneficial in inhibiting a wide range of photodamage, however most formulations provide very little protection in the long wave UVA region (380–400 nm) and almost none from shortwave visible wavelengths (400–420 nm). We demonstrate photodamage in this region for a number of different endpoints including cell viability, DNA damage (delayed cyclobutane pyrimidine dimers), differential gene expression (for genes associated with inflammation, oxidative stress and photoageing) and induction of oxidizing species in vitro in HaCaT keratinocytes and in vivo in human volunteers. This work has implications for phototherapy and photoprotection.

Melanin distribution in human epidermis affords localized protection against DNA photodamage and concurs with skin cancer incidence difference in extreme phototypes

Epidermal DNA damage, especially to the basal layer, is an established cause of keratinocyte cancers (KCs). Large differences in KC incidence (20- to 60-fold) between white and black populations are largely attributable to epidermal melanin photoprotection in the latter. The cyclobutane pyrimidine dimer (CPD) is the most mutagenic DNA photolesion; however, most studies suggest that melanin photoprotection against CPD is modest and cannot explain the considerable skin color-based differences in KC incidence. Along with melanin quantity, solar-simulated radiation-induced CPD assessed immediately postexposure in the overall epidermis and within 3 epidermal zones was compared in black West Africans and fair Europeans. Melanin in black skin protected against CPD by 8.0-fold in the overall epidermis and by 59.0-, 16.5-, and 5.0-fold in the basal, middle, and upper epidermis, respectively. Protection was related to the distribution of melanin, which was most concentrated in the basal layer of black skin. These results may explain, at least in part, the considerable skin color differences in KC incidence. These data suggest that a DNA protection factor of at least 60 is necessary in sunscreens to reduce white skin KC incidence to a level that is comparable with that of black skin.-Fajuyigbe, D., Lwin, S. M., Diffey, B. L., Baker, R., Tobin, D. J., Sarkany, R. P. E., Young, A. R. Melanin distribution in human epidermis affords localized protection against DNA photodamage and concurs with skin cancer incidence difference in extreme phototypes.

Xeroderma pigmentosum is a definite cause of Huntington's disease-like syndrome

Xeroderma pigmentosum is characterized by cutaneous, ophthalmological, and neurological features. Although it is typical of childhood, late presentations can mimic different neurodegenerative conditions. We report two families presenting as Huntington's disease‐like syndromes. The first case (group G) presented with neuropsychiatric features, cognitive decline and chorea. Typical lentigines were only noticed after the neurological disease started. The second case (group B) presented adult‐onset chorea and neuropsychiatric symptoms after an aggressive ocular melanoma. Xeroderma pigmentosum can manifest as a Huntington's Disease‐like syndrome. Classic dermatological and oncological features have to be investigated in choreic patients with negative genetic tests for Huntington's disease‐like phenotypes.

Making sense of the porphyrias

Patients with cutaneous porphyrias can be worrying for dermatologists. The diseases are rare enough to be unfamiliar, are associated with internal diseases, can have genetic implications, and are associated with incomprehensible biochemical pathways. In this review, I will try to explain why porphyrias occur, why they present as they do in the clinic, and provide a checklist for treating patients with porphyria.

Acquired erythropoietic protoporphyria as a result of myelodysplasia causing loss of chromosome 18

We report a patient aged 73 years, who developed erythropoietic protoporphyria with typical photosensitivity, at the same time as she was diagnosed as having myelodysplastic syndrome. The myelodysplastic clone in her bone marrow completely lacked one of the two copies of chromosome 18. As chromosome 18 is the locus of the ferrochelatase gene, we postulate that this chromosomal deletion led to reduced synthesis of the enzyme in the bone marrow clone, so causing the porphyria. The nature of the remaining ferrochelatase allele was examined by polymorphism analysis and we discuss the insights that this patient's genotype may reveal about the pathogenesis of porphyria in myelodysplasia.

Ferrochelatase gene polymorphism analysis for accurate genetic counselling in erythropoietic protoporphyria

It has recently been shown that most cases of clinically overt erythropoietic protoporphyria (EPP) result from coinheritance of a mutated ferrochelatase gene and a commonly occurring low-expression normal variant allele. The identification of two polymorphic variant sequences associated with this low-expression allele now enables improved predictive counselling for couples where one partner has EPP. We describe a patient and his spouse in whom we have used such genetic analysis to provide an accurate estimate of the chance that their future offspring may suffer from EPP.

Erythropoietic protoporphyria (EPP) at 40. Where are we now?

Since Professor Magnus first defined erythropoietic protoporphyria (EPP) in 1961, there has been considerable progress in the understanding this disease. The past decade has been a period of spectacular progress in understanding the genetics and pathogenesis of the disease by molecular investigation. However, progress in therapy for EPP has been slower, and has been dogged by difficulty in assessing treatment efficacy in patients. We are now entering an era in which advances in molecular genetics are directly affecting patient management. This review summarises laboratory and clinical progress in EPP in the past 40 years, and assesses the potential impact of molecular biology on clinical practice.