Mosaicism for ATP2A2 mutations causes segmental Darier's disease

Unmet Needs in Darier's Disease from a Patient's Perspective: Lessons Learnt from the German Registry

The MDHHgermany registry was initiated to characterize the "real-life" situation of affected individuals with Darier's disease (DD; Morbus Darier, MD) and Hailey-Hailey disease (HH), including their treatment and healthcare. To gain deeper insights into medical care of patients with DD, various aspects such as demographics, subjective symptoms, patient satisfaction with medical care, past and current therapies were explored. Patients with diagnosed DD were included. Subjective symptoms such as itch, pain and burning sensation were assessed. Individual therapy goals were recorded and patients assessed previous/current therapies along with satisfaction of medical care and treatment. A total of 55 patients were recruited; 47 patients were eligible for the analysis. Pruritus was rated the most bothersome symptom. Some 42.6% had not received systemic treatment so far or systemic therapies were rated ineffective (32.6%). Most commonly oral retinoids were prescribed, followed by corticosteroids. Patient satisfaction with medical care and treatment proved to be mediocre. This "real-life" data show an alarming unmet need regarding patients' satisfaction with medical care and treatment, evidenced by the reported lack of disease control. Further studies and interventions are needed to improve the spectrum of available therapies. MDHHgermany provides a foundational platform for future clinical trials, epidemiological studies, and pathophysiological analyses.

Persistent Cutaneous Lesions of Darier Disease and Second-Hit Somatic Variants in ATP2A2 Gene

Importance

Darier disease (DD) is a rare genetic skin disorder caused by heterozygous variants in the ATP2A2 gene. Clinical manifestations include recurrent hyperkeratotic papules and plaques that occur mainly in seborrheic areas. Although some of the lesions wax and wane in response to environmental factors, others are severe and respond poorly to therapy.

Objective

To investigate the molecular mechanism underlying the persistency of skin lesions in DD.

Design, Setting, and Participants

In this case series, DNA was extracted from unaffected skin, transient and persistent lesional skin, and blood from 9 patients with DD. Genetic analysis was used using paired-whole exome sequencing of affected skin and blood or by deep sequencing of ATP2A2 of affected skin. Chromosomal microarray analysis was used to reveal copy number variants and loss of heterozygosity. All variants were validated by Sanger sequencing or restriction fragment length polymorphism.

Interventions or Exposures

Paired whole-exome sequencing and deep sequencing of ATP2A2 gene from blood and skin samples isolated from persistent, transient lesions and unaffected skin in patients with DD.

Main Outcomes and Measures

Germline and somatic genomic characteristics of persistent and transient cutaneous lesions in DD.

Results

Of 9 patients with DD, all had heterozygous pathogenic germline variants in the ATP2A2 gene, 6 were female. Participant age ranged from 40 to 69 years on enrollment. All 11 persistent skin lesions were associated with second-hit somatic variants in the ATP2A2 gene. The somatic variants were classified as highly deleterious via combined annotation-dependent depletion (CADD) scores or affect splicing, and 3 of them had been previously described in patients with DD and acrokeratosis verruciformis of Hopf. Second-hit variants in the ATP2A2 gene were not identified in the transient lesions (n = 2) or the normal skin (n = 2).

Conclusions and Relevance

In this study, persistent DD lesions were associated with the presence of second-hit somatic variants in the ATP2A2 gene. Identification of these second-hit variants offers valuable insight into the underlying mechanisms that contribute to the lasting nature of persistent DD lesions.

Association of Somatic ATP2A2 Damaging Variants With Grover Disease

Importance

Grover disease (GD), a truncal eruption that typically occurs in older individuals, is exacerbated by sweating, irradiation, cancers, medications, kidney failure, and organ transplantation. The pathobiology of GD remains unknown.

Objective

To determine if damaging somatic single-nucleotide variants (SNVs) are associated with GD.

Design, Setting, and Participants

In this retrospective case series, we identified consecutive patients from a dermatopathology archive over a 4-year period (January 2007 to December 2011) who had 1 biopsy with a clinical diagnosis of GD confirmed via histopathologic findings and another non-GD biopsy. Participant DNA was extracted from both biopsy tissues and sequenced to high depth with a 51-gene panel to screen for SNVs in genes previously associated with acantholysis and Mendelian disorders of cornification. Analysis took place between 2021 and 2023.

Main Outcomes and Measures

Comparative analysis of sequencing data from paired GD and control tissue was employed to identify SNVs predicted to affect gene function, which were exclusive to, or highly enriched in, GD tissue.

Results

Overall, 12 of 15 cases of GD (12 men and 3 women; mean [SD] age, 68.3 [10.0] years) were associated with C>T or G>A ATP2A2 SNVs in GD tissue; all were predicted to be highly damaging via combined annotation dependent depletion (CADD) scores, and 4 were previously associated with Darier disease. In 9 cases (75%), the GD-associated ATP2A2 SNV was absent from control tissue DNA, and in 3 cases (25%), ATP2A2 SNVs were enriched 4- to 22-fold in GD vs control tissue.

Conclusions and Relevance

In this case series study of 15 patients, damaging somatic ATP2A2 SNVs were associated with GD. This discovery expands the spectrum of acantholytic disorders associated with ATP2A2 SNVs and highlights the role of somatic variation in acquired disorders.

Darier's follicular dyskeratosis

Darier's follicular dyskeratosis (synonym: Dariers disease, DarierWhites disease) is a rare genetic disease with an autosomal dominant type of inheritance, which belongs to the group of acantholytic dermatoses and is characterized by a violation of keratinization processes with lesions of the skin, nails, mucous membranes of the oral cavity and genitals. Dariers disease is caused by a mutation in the ATP2A2 gene. This disrupts the operation of the SERCA2 pump and leads to a violation of calcium homeostasis in keratinocytes and a decrease in intercellular adhesion. Dariers disease is manifested by brownish papules in seborrheic and intertriginal areas with a keratotic surface, which can merge into macerated plaques. Typical nail changes in Dariers disease include red and white longitudinal stripes ending in V-shaped notches on the free edge of the nail plates. Warty acrokeratosis, as well as bullous, hemorrhagic, comedonic and linear-segmental types are clinical variants of Dariers disease. Dariers disease is often associated with neuropsychiatric disorders. Exacerbation may be caused by superinfection with Staphylococcus aureus or by herpes simplex virus. Histology in Darieres disease is characterized by pronounced dyskeratosis. For local therapy, keratolytic agents are important, as well as antiseptic treatment to avoid superinfection. In addition, local corticosteroids are used. Among the systemic methods of treatment, the systemic retinoids are the most effective. Ablative methods of treatment (dermabrasion, CO2 laser, Er:YAG laser) are effective in limited areas.

Epidermal Nevi: What Is New

This article reviews the clinical findings of epidermal nevi and their associated syndromes and provides an update on their pathogenic genetic changes as well as targeted therapies detailed to date.

Darier and Hailey-Hailey disease: update 2021

The autosomal-dominant genodermatoses Darier disease and Hailey-Hailey disease present special challenges to dermatologists. Despite their similar pathogenesis featuring impaired adhesion of suprabasal keratinocytes as a result of defective ATPases in epidermal calcium channels, the two diseases differ considerably in clinical presentation and therapeutic options. Darier disease is characterized by reddish brown, keratotic papules in seborrheic and intertriginous areas, which may coalesce into extensive lesions. Individuals affected with Hailey-Hailey disease primarily develop intertriginous papulovesicles and small blisters, which often evolve into erythematous plaques with erosions and painful fissures. Quality of life is significantly reduced because of complaints (itch, burning sensation, pain), body malodor and chronicity. Therapeutic options remain limited. Antiseptics and intermittent topical corticosteroids are a cornerstone of therapy, and systemic anti-infective treatment is often required in cases of superinfection. Ablative surgical interventions such as dermabrasion and CO₂ laser surgery can lead to long-term remissions in intertriginous Hailey-Hailey disease, while temporary relief may also be achieved by intralesional injections of botulinum toxin. Of the systemic medications available for Darier disease, acitretin, which is approved for this purpose, has the best supporting evidence. The efficacy of immunosuppressants and immune modulators is inconsistent. Low-dose naltrexone produces more satisfactory results in Hailey-Hailey than Darier disease. The present CME article summarizes current knowledge of the two dermatoses, taking recent developments into account.

A six-attribute classification of genetic mosaicism

Mosaicism denotes an individual who has at least two populations of cells with distinct genotypes that are derived from a single fertilized egg. Genetic variation among the cell lines can involve whole chromosomes, structural or copy-number variants, small or single-nucleotide variants, or epigenetic variants. The mutational events that underlie mosaic variants occur during mitotic cell divisions after fertilization and zygote formation. The initiating mutational event can occur in any types of cell at any time in development, leading to enormous variation in the distribution and phenotypic effect of mosaicism. A number of classification proposals have been put forward to classify genetic mosaicism into categories based on the location, pattern, and mechanisms of the disease. We here propose a new classification of genetic mosaicism that considers the affected tissue, the pattern and distribution of the mosaicism, the pathogenicity of the variant, the direction of the change (benign to pathogenic vs. pathogenic to benign), and the postzygotic mutational mechanism. The accurate and comprehensive categorization and subtyping of mosaicisms is important and has potential clinical utility to define the natural history of these disorders, tailor follow-up frequency and interventions, estimate recurrence risks, and guide therapeutic decisions.

Role of Transient Receptor Potential Vanilloid 4 Channel in Skin Physiology and Pathology

Transient receptor potential vanilloid 4 (TRPV4) channel responds to temperature, as well as various mechanical and chemical stimuli. This non-selective cation channel is expressed in several organs, including the blood vessels, kidneys, oesophagus and skin. In the skin, TRPV4 channel is present in various cell types such as keratinocytes, melanocytes and sensory neurons, as well as immune and inflammatory cells, and engages in several physiological actions, from skin homeostasis to sensation. In addition, there is substantial evidence implicating dysfunctional TRPV4 channel—in the form of either deficient or excessive channel activity—in pathological cutaneous conditions such as skin barrier compromise, pruritus, pain, skin inflammation and carcinogenesis. These varied functions, combined with the fact that TRPV4 channel owns pharmacologically-accessible sites, make this channel an attractive therapeutic target for skin disorders. In this review, we summarize the different physiological and pathophysiological effects of TRPV4 in the skin.

Mosaicism in genodermatoses

Genodermatoses are inherited disorders presenting with cutaneous manifestations with or without the involvement of other systems. The majority of these disorders, particularly in cases that present with a cutaneous patterning, may be explained in the context of genetic mosaicism. Despite the barriers to the genetic analysis of mosaic disorders, next-generation sequencing has led to a substantial progress in understanding their pathogenesis, which has significant implications for the clinical management and genetic counseling. Advances in paired and deep sequencing technologies in particular have made the study of mosaic disorders more feasible. In this review, we provide an overview of genetic mosaicism as well as mosaic cutaneous disorders and the techniques required to study them.

Mid borderline leprosy in type Bα Blaschko linear pattern: a rare phenomenon

INTRODUCTION

Leprosy is a chronic granulomatous disease caused by M. leprae. It is a great imitator as it can manifest in different unusual and atypical ways. Mid borderline leprosy (BB) is an unstable form representing the immunologic midpoint in the clinical spectrum.

CASE REPORT

Here, we report a case of BB leprosy having classical inverted saucer-shaped lesions elsewhere on the body with a linear psoriasiform lesion over the left forearm following the lines of Blaschko. Biopsy from this lesion revealed granulomas consisting of equal admixture of epithelioid cells and macrophages without multinucleate giant cells suggesting mid borderline leprosy.

CONCLUSION

Occurrence of lesions in a Blaschko linear pattern supports the role of genetic susceptibility to leprosy. The genetically vulnerable cells along the lines of Blaschko were infected while the surrounding cells remained unaffected. This explains the concept of locus minoris resistentiae due to cutaneous mosaicism.

Case for diagnosis. Linear Darier's disease

We present a different and rare manifestation of Darier's disease, namely linear Darier's disease. Only a few cases have been described in the literature. The case report is a male patient, 60 years old, presenting brown to red papules and plaques with hyperkeratosis distributed on the abdomen, following Blaschko's lines, with 6 years' evolution. It was a difficult diagnosis until the dermatological workup and biopsy.

Epidermal Nevi and Related Syndromes -- Part 1: Keratinocytic Nevi

Epidermal nevi are hamartomatous lesions derived from the epidermis and/or adnexal structures of the skin; they have traditionally been classified according to their morphology. New variants have been described in recent years and advances in genetics have contributed to better characterization of these lesions and an improved understanding of their relationship with certain extracutaneous manifestations. In the first part of this review article, we will look at nevi derived specifically from the epidermis and associated syndromes.

The role of the ATP2C1 gene in Hailey-Hailey disease

Hailey-Hailey disease (HHD) is a rare autosomal dominant acantholytic dermatosis, characterized by a chronic course of repeated and exacerbated skin lesions in friction regions. The pathogenic gene of HHD was reported to be the ATPase calcium-transporting type 2C member 1 gene (ATP2C1) located on chromosome 3q21-q24. Its function is to maintain normal intracellular concentrations of Ca2+/Mn2+ by transporting Ca2+/Mn2+ into the Golgi apparatus. ATP2C1 gene mutations are reportedly responsible for abnormal cytosolic Ca2+/Mn2+ levels and the clinical manifestations of HHD. Environmental factors and genetic modifiers may also affect the clinical variability of HHD. This article aims to critically discuss the clinical and pathological features of HHD, differential diagnoses, and genetic and functional studies of the ATP2C1 gene in HHD. Further understanding the role of the ATP2C1 gene in the pathogenesis of HHD by genetic, molecular, and animal studies may contribute to a better clinical diagnosis and provide new strategies for the treatment and prevention of HHD.

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.

TRP Channels in Skin Biology and Pathophysiology

Ion channels of the Transient Receptor Potential (TRP) family mediate the influx of monovalent and/or divalent cations into cells in response to a host of chemical or physical stimuli. In the skin, TRP channels are expressed in many cell types, including keratinocytes, sensory neurons, melanocytes, and immune/inflammatory cells. Within these diverse cell types, TRP channels participate in physiological processes ranging from sensation to skin homeostasis. In addition, there is a growing body of evidence implicating abnormal TRP channel function, as a product of excessive or deficient channel activity, in pathological skin conditions such as chronic pain and itch, dermatitis, vitiligo, alopecia, wound healing, skin carcinogenesis, and skin barrier compromise. These diverse functions, coupled with the fact that many TRP channels possess pharmacologically accessible sites, make this family of proteins appealing therapeutic targets for skin disorders.

Somatic mosaicism and disease

The large number of cell divisions required to make a human body inevitably leads to the accumulation of somatic mutations. Such mutations cause individuals to be somatic mosaics. Recent advances in genomic technology now allow measurement of somatic diversity. Initial studies confirmed the expected high levels of somatic mutations within individuals. Going forward, the big questions concern the degree to which those somatic mutations influence disease. Theory predicts that the frequency of mutant cells should vary greatly between individuals. Such somatic mutational variability between individuals could explain much of the diversity in the risk of disease. But how variable is mosaicism between individuals in reality? What is the relation between the fraction of cells carrying a predisposing mutation and the risk of disease? What kinds of heritable somatic change lead to disease besides classical DNA mutations? What molecular processes connect a predisposing somatic change to disease? We know that predisposing somatic mutations strongly influence the onset of cancer. Likewise, neurodegenerative diseases may often begin from somatically mutated cells. If so, both neurodegeneration and cancer may be diseases of later life for which much of the risk may be set by early life somatic mutations.

Mosaic Neurocutaneous Disorders and Their Causes

Neurocutaneous disorders are a heterogeneous group of conditions (mainly) affecting the skin [with pigmentary/vascular abnormalities and/or cutaneous tumours] and the central and peripheral nervous system [with congenital abnormalities and/or tumours]. In a number of such disorders, the skin abnormalities can assume a mosaic patterning (usually arranged in archetypical patterns). Alternating segments of affected and unaffected skin or segmentally arranged patterns of abnormal skin often mirror similar phenomena occurring in extra-cutaneous organs/tissues [eg, eye, bone, heart/vessels, lung, kidney and gut]. In some neurocutaneous syndromes the abnormal mosaic patterning involve mainly the skin and the nervous system configuring a (true) mosaic neurocutaneous disorder; or an ordinary trait of a neurocutaneous disorder is sometimes superimposed by a pronounced linear or otherwise segmental involvement; or, lastly, a neurocutaneous disorder can occur solely in a mosaic pattern. Recently, the molecular genetic and cellular bases of an increasing number of neurocutaneous disorders have been unravelled, shedding light on the interplays between common intra- and extra-neuronal signalling pathways encompassing receptor-protein and protein-to-protein cascades (eg, RAS, MAPK, mTOR, PI3K/AKT and GNAQ pathways), which are often responsible of the mosaic distribution of cutaneous and extra-cutaneous features. In this article we will focus on the well known, and less defined mosaic neurocutaneous phenotypes and their related molecular/genetic bases, including the mosaic neurofibromatoses and their related forms (ie, spinal neurofibromatosis and schwannomatosis); Legius syndrome; segmental arrangements in tuberous sclerosis; Sturge-Weber and Klippel-Trenaunay syndromes; microcephaly/megalencephaly-capillary malformation; blue rubber bleb nevus syndrome; Wyburn-Mason syndrome; mixed vascular nevus syndrome; PHACE syndrome; Incontinentia pigmenti; pigmentary mosaicism of the Ito type; neurocutaneous melanosis; cutis tricolor; speckled lentiginous syndrome; epidermal nevus syndromes; Becker's nevus syndrome; phacomatosis pigmentovascularis and pigmentokeratotica; Proteus syndrome; and encephalocraniocutaneous lipomatosis.

Linear Darier's disease: A case with bilateral presentation

Darier's disease is an autosomal dominant genodermatosis characterized by a persistent eruption of hyperkeratotic greasy papules mainly over the seborrheic sites of the body, usually associated with nail abnormalities and sometimes with mucous membrane lesions. The lesions typically occur in the younger age group and are associated with pruritus. We report here an atypical case of Linear Darier's disease with bilateral presentation in a middle-aged adult that could be confused with conditions such as lichen planus, inflammatory linear verrucous epidermal nevus, and wart.

Hypopigmented Segmental Darier Disease

Background:

Darier disease is a genodermatosis caused by a mutation in the ATP2A2 gene. It classically presents as hyperkeratotic greasy papules in a seborrheic distribution. Several variants have been reported, notably the hypopigmented variant, which predominantly targets dark-skinned individuals, and a segmental variant that often follows the lines of Blaschko.

Methods:

We report a case of a 41-year-old African-Canadian female with a long-standing history of macular hypopigmented pruritic eruption following the lines of Blaschko on her back. The eruption was persistent and recalcitrant to various treatments. Dyskeratosis with corps ronds and grains, acantholysis, and parakeratosis were observed on histopathology. Those findings were consistent with the diagnosis of segmental hypopigmented Darier disease.

Results and conclusions:

To our knowledge, this is the first case reporting a combined segmental and hypopigmented variant of Darier disease. We further present a literature review for hypopigmented and segmental variants of Darier disease.

The genetics of human skin disease

The skin is composed of a variety of cell types expressing specific molecules and possessing different properties that facilitate the complex interactions and intercellular communication essential for maintaining the structural integrity of the skin. Importantly, a single mutation in one of these molecules can disrupt the entire organization and function of these essential networks, leading to cell separation, blistering, and other striking phenotypes observed in inherited skin diseases. Over the past several decades, the genetic basis of many monogenic skin diseases has been elucidated using classical genetic techniques. Importantly, the findings from these studies has shed light onto the many classes of molecules and essential genetic as well as molecular interactions that lend the skin its rigid, yet flexible properties. With the advent of the human genome project, next-generation sequencing techniques, as well as several other recently developed methods, tremendous progress has been made in dissecting the genetic architecture of complex, non-Mendelian skin diseases.

Adolescent Onset of Localized Papillomatosis, Lymphedema, and Multiple Beta-Papillomavirus Infection: Epidermal Nevus, Segmental Lymphedema Praecox, or Verrucosis? A Case Report and Case Series of Epidermal Nevi

Herein, we report the case of a 12-year-old female who noted the recent onset of an oval, circumscribed, 10-cm papillomatous plaque affecting the thigh and vulva that showed histologic signs of lymphedema without evidence of secondary lymphedema. The sequencing of genes associated with a delayed onset of lymphedema or epidermal nevi (EN) - GATA2 and GJC2, and HRAS and KRAS, respectively - showed wild-type alleles. Polymerase chain reaction for human papillomavirus (HPV) DNA demonstrated infections with 15 HPV genotypes. Evidence of productive HPV infection, HPV capsid expression, and cytopathic changes was detected. At the 6-month follow-up, no evidence of recurrence was found after complete excision. The analysis of a consecutive series of 91 EN excision specimens revealed that 76% exhibited histologic evidence of lymphostasis. Notably, multiple acrochordon-like EN, which most closely resembled this case, showed similar signs of localized lymphedema. The late onset and evidence of lymphedema favors the diagnosis of congenital unisegmental lymphedema. However, the clinical findings and epidermal changes point to the diagnosis of EN. Moreover, localized verrucosis also accurately describes this patient's cutaneous findings. Based on the above evidence, we postulate that an abnormal development of lymphatics may play a primary role in the pathogenesis of some types of EN and facilitate productive HPV infection.

Case for diagnosis: Linear Darier

Linear Darier is a rare variant of Darier's Disease. The keratotic papules follow Blaschko's lines, characterizing the cutaneous mosaicism. We report the case of a 42-year-old woman who presented with small, linearly distributed, reddish-brown papules on the left mammary region, from the left flank to the hypogastrium and on the pretibial area of the left leg. Histologically, suprabasal acantholysis and dyskeratotic cells were seen, confirming the diagnosis.

Grover's disease following multiple bilateral Blaschko lines: a rare clinical presentation with genetic and electron microscopic analyses

Grover's disease is an acquired dermatosis of unknown cause histopathologically characterized by the presence of acantholysis. We report an 83-year-old Japanese man who showed multiple pruritic papular lesions distributed bilaterally along Blaschko lines, necessitating the exclusion of segmental Darier's disease. No mutations in ATP2A2, ATP2C1 or keratin 5 genes were found both in the lesional skin and in peripheral leukocytes, suggesting that putative pathogenesis of Grover's disease is distinct from those of other acantholytic dermatoses. Electron microscopy revealed poorly developed tonofibrils in the basal cells, and the structure of desmosomes appeared normal, with an increase in the number of desmosomes in the spinous layer, indicating compensation of defective desmosomal function. Impairment of desmosomal plaque proteins linking tonofilaments to desmosomal cadherins may thus account for acantholysis. The unusual bilateral mosaic arrangement in our patient may offer valuable clues to the genetic basis of Grover's disease.

Pigmentary nevi on face have unique patterns and implications: The concept of Blaschko's lines for pigmentary nevi

Background:

Nevi are proposed to reflect the mosaicism and thus generally follow the different archetypal patterns of mosaicism. Blaschko's lines are the most common pattern of mosaicism. There have been many attempts to elucidate the Blaschko's lines on face from the distributional patterns of different nevi, but studies that evaluated exclusively pigmentary nevi are sparse. Aims: This study attempted to evaluate the patterns followed by different pigmentary nevi on face and utilized this to elucidate the pattern of embryological pigmentation on face.

Materials and Methods:

Spatial parameters like shape, orientation, and distribution patterns of different flat pigmentary nevi on face were analyzed and graphically drawn on human facial diagram. This was compared with existing facial Blaschko's lines. All cases of palpable pigmented nevi like congenital and giant melanocytic nevi and nevus spilus were excluded.

Results:

A total of 68 cases of pigmentary nevi on face (male-39, female-29) were examined. The shape and distribution lines were found to have a close similarity with Blaschko's lines on face with distinct differences.

Conclusions:

The concept of facial embryonic pigmentary ‘segment’, ‘unit’ and existence of separate Blaschko's lines for facial pigmentary nevi is conceived. Some insight into the pathogenesis of Blaschko's lines is also proposed in this study.

Patterned disorders in dermatology

The skin gives us an opportunity to study pathologies unapparent in other systems such as patterned disorders. Among the best-identified patterns of skin disorders are the well-known lines of Blaschko, but other types of skin-patterned lesions have also been recognized. This short review will describe and discuss these different patterns and their pathophysiologic mechanisms, such as somatic mosaicism and X-chromosome associated mosaicism. Cutaneous patterned disorders are thought to be associated usually with inherited diseases per se, but in fact they are also reported in so-called acquired diseases. These cases suggest the existence of an underlying defect in a gene closely associated with the disease pathogenesis. The study of these acquired patterned disorders in the future may help us to understand the biologic foundations and pathogenesis of common human diseases.

Successful treatment of combination therapy with tacalcitol lotion associated with sunscreen for localized Darier's disease

We herein report a sporadic case of Darier's disease localized to the bilateral side of the neck in a 39-year-old Japanese woman. Several clinical variants of Darier's disease have so far been recognized including unilateral Darier's disease, localized Darier's disease, segmental Darier's disease and acral Darier's disease. Few cases of Darier's disease, restricted to sun-exposed areas such as the bilateral side of the neck, have been described in the published work. It remains controversial, however, whether ultraviolet exposure can induce the onset of Darier's disease. Our patient's skin lesions, which were resistant to previous treatment with corticosteroid, improved substantially with high-concentration tacalcitol lotion and sunscreen. This is the first report on the efficacy of topical tacalcitol lotion associated with sunscreen for the treatment of localized Darier's disease.

[Segmental Darier disease : treatment with pulsed dye laser]

Darier disease is often associated with pruritus and an unpleasant odor, causing medical and emotional problems. Ablative laser therapy has proven effective in ameliorating these symptoms. Side effects of this approach include permanent hypopigmentation and a risk of scarring. We present two cases where non-ablative therapy with pulsed dye lasers proved a safe and effective way to manage the intertriginous lesions. Although the mechanism of action is unclear, our success indicates that pulsed dye laser therapy is an option in Darier disease. Larger numbers of patients, ideally in multicenter studies, must be treated in this way to confirm our results.

Patterns in naevoid skin disease: development, disease and modelling

The aetiology of pattern-formation in human naevoid skin disease remains unknown. However, it is likely that the majority of previously proposed mechanisms - those that simply rely on passive clonal trafficking in embryogenesis - are incomplete. A more comprehensive explanation for pattern-formation in naevi invokes the principle of self-organization. We define two types of patterning: anatomical and functional. Anatomical patterning is where the abnormal clone is limited to regions of pathologic skin, while functional patterning is where the abnormal clone and pathologic skin are spatially uncorrelated. From a theoretical perspective self-organized naevoid patterns may be either secondary to local interactions between normal and aberrant genotypes or due to the interaction between aberrant genotypes and the presence of normal embryonic patterning cues. The latter possibility suggests the critical observation and analysis of patterns in naevoid skin disease may lead to unique insights into key aspects of early human embryogenesis.

Four novel ATP2A2 mutations in Slovenian patients with Darier disease

BACKGROUND

Darier disease (DD) is an autosomal dominant genodermatosis caused by mutations in the ATP2A2 gene. It has been reported that depletion of Ca(2+) stores within the endoplasmic reticulum of keratinocytes is associated with impaired cell cycle regulation and terminal differentiation. Mechanical stress, heat, or UV irradiation might delay cell cycle exit and permit progression into the quiescent stage without repair. When there is associated DNA damage, this can lead to an accumulation of secondary somatic mutations and possible clonal proliferation of damaged keratinocyes within keratotic papules and plaques.

OBJECTIVE

We sought to present clinical, demographic, and genetic analysis of the cohort of Slovenian patients with DD, which represents 52% of DD patients in the country.

METHODS

We examined 28 Slovenians with DD and screened genomic DNA for ATP2A2 mutations and RNA for splice site mutations.

RESULTS

The estimated prevalence of the disease in Slovenia is 2.7/100.000. We identified 7 different ATP2A2 mutations, 4 of which are novel: A516P, R559G, 463-6del6, and 1762-6del18. We also found two previously described polymorphisms in intron XVIII (2741 + 54 G>A) and in exon 15 (2172 G>A; A724A), with allele frequencies of 64.15% and 11.32%, respectively. There was a history of perceptive deafness in two DD patients from two families.

LIMITATIONS

Analysis of SERCA2 expression, measurements of Ca(2+) uptake and their influence on desmosomal assembly in vitro would add additional value to the study. Although single-stranded conformational analysis (SSCP) is a common and accepted method for screening for the presence of mutations, it does miss 10% to 20% of mutations.

CONCLUSIONS

We identified 4 novel ATP2A2 mutations in Slovenian patients with DD. Deafness seems to be a new phenotypic characteristic of DD patients.

Linear morphoea follows Blaschko's lines

BACKGROUND

The aetiology of morphoea (or localized scleroderma) remains unknown. It has previously been suggested that lesions of linear morphoea may follow Blaschko's lines and thus reflect an embryological development. However, the distribution of linear morphoea has never been accurately evaluated.

OBJECTIVES

We aimed to identify common patterns of clinical presentation in children with linear morphoea and to establish whether linear morphoea follows the lines of Blaschko.

METHODS

A retrospective chart review of 65 children with linear morphoea was performed. According to clinical photographs the skin lesions of these patients were plotted on to standardized head and body charts. With the aid of Adobe Illustrator a final figure was produced including an overlay of all individual lesions which was used for comparison with the published lines of Blaschko.

RESULTS

Thirty-four (53%) patients had the en coup de sabre subtype, 27 (41%) presented with linear morphoea on the trunk and/or limbs and four (6%) children had a combination of the two. In 55 (85%) children the skin lesions were confined to one side of the body, showing no preference for either left or right side. On comparing the overlays of all body and head lesions with the original lines of Blaschko there was an excellent correlation.

CONCLUSIONS

Our data indicate that linear morphoea follows the lines of Blaschko. We hypothesize that in patients with linear morphoea susceptible cells are present in a mosaic state and that exposure to some trigger factor may result in the development of this condition.