Exacerbation, then clearance, of mutation-proven Darier's disease of the skin after radiotherapy for bronchial carcinoma: a case of radiation-induced epidermal differentiation?

Temperature instability of a mutation at a multidomain junction in Na,K-ATPase isoform ATP1A3 (p.Arg756His) produces a fever-induced neurological syndrome

ATP1A3 encodes the α3 isoform of Na,K-ATPase. In the brain, it is expressed only in neurons. Human ATP1A3 mutations produce a wide spectrum of phenotypes, but particular syndromes are associated with unique substitutions. For arginine 756, at the junction of membrane and cytoplasmic domains, mutations produce encephalopathy during febrile infections. Here we tested the pathogenicity of p.Arg756His (R756H) in isogenic mammalian cells. R756H protein had sufficient transport activity to support cells when endogenous ATP1A1 was inhibited. It had half the turnover rate of wildtype, reduced affinity for Na⁺, and increased affinity for K⁺. There was modest endoplasmic reticulum retention during biosynthesis at 37 °C but little benefit from the folding drug phenylbutyrate (4-PBA), suggesting a tolerated level of misfolding. When cells were incubated at just 39 °C, however, α3 protein level dropped without loss of β subunit, paralleled by an increase of endogenous α1. Elevated temperature resulted in internalization of α3 from the surface along with some β subunit, accompanied by cytoplasmic redistribution of a marker of lysosomes and endosomes, lysosomal-associated membrane protein 1. After return to 37 °C, α3 protein levels recovered with cycloheximide-sensitive new protein synthesis. Heating in vitro showed activity loss at a rate 20- to 30-fold faster than wildtype, indicating a temperature-dependent destabilization of protein structure. Arg756 appears to confer thermal resistance as an anchor, forming hydrogen bonds among four linearly distant parts of the Na,K-ATPase structure. Taken together, our observations are consistent with fever-induced symptoms in patients.

Therapeutic Options for the Treatment of Darier's Disease: A Comprehensive Review of the Literature

Darier's disease (also known as keratosis follicularis or dyskeratosis follicularis) is an autosomal dominant inherited disorder which manifests as hyperkeratotic greasy papules in the first or second decade of life. Aside from symptom management and behavioral modifications to avoid triggers, there are currently no validated treatments for Darier's disease (DD). However, a variety of treatments have been proposed in the literature including retinoids, steroids, vitamin D analogs, photodynamic therapy, and surgical excision. The purpose of this review article is to identify therapeutic options for treating DD and to outline the evidence underlying these interventions. A search was conducted in Medline for English language articles from inception to July 4, 2020. Our search identified a total of 474 nonduplicate studies, which were screened by title and abstract. Of these, 155 full text articles were screened against inclusion/exclusion criteria, and 113 studies were included in our review. We identified Grade B evidence for the following treatments of DD: oral acitretin, oral isotretinoin, systemic Vitamin A, topical tretinoin, topical isotretinoin, topical adapalene gel, topical 5-flououracil, topical calciptriol and tacalcitol (with sunscreen), grenz ray radiation, and x-ray radiation. All other evidence for treatments of DD consisted of case reports or case series, which is considered grade C evidence. Considering the quality and quantity of evidence, clinicians may consider initiating a trial of select topical or oral retinoids first in patients with localized or generalized DD, respectively.

Management of Darier disease: A review of the literature and update

Darier disease (DD) is a rare type of inherited keratinizing disorder with no definitive therapeutic approach. The objective of this study is to provide a detailed literature review of all the available treatment modalities of Darier disease, including those that are both surgical and non surgical, to compare their efficacies and to propose a novel therapeutic approach. A complete search of the literature for all articles describing the different treatments of Darier disease, with no restrictions on patients' ages, gender or nationalities, was performed with the use of PubMed. A total of 68 articles were included in the study: 3 prospective studies, 44 case reports/case series and 21 letters/correspondences/clinical images. The treatments described were topical, oral or physical. Retinoids (isotretinoin, tazarotene and adapalene) and fluorouracil were the two most effective topical treatments. Oral retinoids were the most effective oral therapy and were prescribed in the cases of generalized Darier disease. For localized and resistant skin lesions, physical therapies including surgical excision, dermabrasion and CO2 laser ablation were the first line choices. Limitations of this article include the inability to verify the accuracy of the published data, the relatively small sample size, the absence of randomized controlled clinical trials and possible unidentified confounding factors in various studies. In every therapeutic approach to Darier disease, consideration of patient comorbidities, disease distribution, severity and treatment accessibility is essential. Large and randomized clinical trials are necessary for the comparison of the efficacy and the safety of all the treatments of Darier disease and settling a consensus for management.

Mendelian Disorders of Cornification Caused by Defects in Intracellular Calcium Pumps: Mutation Update and Database for Variants in ATP2A2 and ATP2C1 Associated with Darier Disease and Hailey-Hailey Disease

The two disorders of cornification associated with mutations in genes coding for intracellular calcium pumps are Darier disease (DD) and Hailey-Hailey disease (HHD). DD is caused by mutations in the ATP2A2 gene, whereas the ATP2C1 gene is associated with HHD. Both are inherited as autosomal-dominant traits. DD is mainly defined by warty papules in seborrheic and flexural areas, whereas the major symptoms of HHD are vesicles and erosions in flexural skin. Both phenotypes are highly variable. In 12%-40% of DD patients and 12%-55% of HHD patients, no mutations in ATP2A2 or ATP2C1 are found. We provide a comprehensive review of clinical variability in DD and HHD and a review of all reported mutations in ATP2A2 and ATP2C1. Having the entire spectrum of ATP2A2 and ATP2C1 variants allows us to address the question of a genotype-phenotype correlation, which has not been settled unequivocally in DD and HHD. We created a database for all mutations in ATP2A2 and ATP2C1 using the Leiden Open Variation Database (LOVD v3.0), for variants reported in the literature and future inclusions. This data may be of use as a reference tool in further research on treatment of DD and HHD.

Efficacy of the Radiotherapy on Darier's Disease: An Indirect Evidence

Darier's disease (DD) is an autosomal dominant dermatosis characterized by hyperkeratotic papules that are mainly located in the seborrheic areas and pushups, handheld wells, and nails. The disease often appears at a young age, typically by the third decade, with no sex predilection. There is currently no standard therapy and there are usually topical palliative therapies. We present the case of an affected 42-year-old woman treated with radiation therapy for early breast cancer. Before the radiotherapy, the patient showed hyperkeratotic, brownish papules extending in a linear pattern for the neck to the abdomen, especially on both breasts and inframammary area. During the radiation, she developed grade 1 to 2 dermatitis in the irradiated area. At a followup of 6 months, the patient has no skin lesions in the irradiated zone. This report suggests that the radiotherapy is not contraindicated and may indeed be effective in local control of skin lesions in DD.

Alterations in the ATP2A2 gene in correlation with colon and lung cancer

Sarcoendoplasmic reticulum calcium transport ATPases (SERCA-type calcium pumps), proteins that accumulate calcium in the endoplasmic reticulum, play an important role in numerous signaling pathways controlling tumor growth, differentiation, and cell death. Reports that Atp2a2 (Serca2) haploinsufficient mice often developed cancer prompted us to study the involvement of the ATP2A2 gene in human cancer development. We found 13 different novel alterations of the ATP2A2 gene in 27 of 416 alleles of patients with two different types of cancer. Changes in ATP2A2 were significantly more common in patients with colon cancer (P < 0.0001, odds ratio OR = 25.3) or lung cancer (P = 0.046, OR = 8.05). The 13 alterations were missense mutations (2), intronic deletions (2), intronic insertions (1), and single-nucleotide alterations (8: two in the coding region, three in the intronic region, and three in the promoter region). We detected lost or reduced expression of ATP2A2 in all patients with alterations in the promoter region, as well as in patients with a combination of gene alterations. Our results suggest that germline alterations of ATP2A2 may predispose to lung and colon cancer and that an impaired ATP2A2 gene might be involved, directly or indirectly, as an early event in carcinogenesis.