Inactivating PTH/PTHrP Signaling Disorders.

Pseudohypoparathyroidism (PHP), pseudo-PHP, acrodysostosis, and progressive osseous heteroplasia are heterogeneous disorders characterized by physical findings, differently associated in each subtype, including short bones, short stature, a stocky build, ectopic ossifications (features associated with Albright's hereditary osteodystrophy), as well as laboratory abnormalities consistent with hormone resistance, such as hypocalcemia, hyperphosphatemia, and elevated parathyroid hormone (PTH) and thyroid-stimulating hormone levels. All these disorders are caused by impairments in the cAMP-mediated signal transduction pathway and, in particular, in the PTH/PTHrP signaling pathway: the main subtypes of PHP and related disorders are caused by de novo or autosomal dominantly inherited inactivating genetic mutations, and/or epigenetic, sporadic, or genetic-based alterations within or upstream of GNAS, PRKAR1A, PDE4D, and PDE3A. Here we will review the impressive progress that has been made over the past 30 years on the pathophysiology of these diseases and will describe the recently proposed novel nomenclature and classification. The new term "inactivating PTH/PTHrP signaling disorder," iPPSD: (1) defines the common mechanism responsible for all diseases, (2) does not require a confirmed genetic defect, (3) avoids ambiguous terms like "pseudo," and (4) eliminates the clinical or molecular overlap between diseases.

Dissecting folliculitis (dissecting cellulitis) of the scalp: a 66-patient case series and proposal of classification.

BACKGROUND AND OBJECTIVES: Dissecting folliculitis (DF) or dissecting cellulitis of the scalp is regarded as a rare disease with disfiguring scarring alopecia. This study aimed to analyze the features of DF and to propose a classification to define its severity. PATIENTS AND METHODS: A hospital-based retrospective study was conducted. Patients with a histopathological diagnosis or clinical features leading to diagnosis of DF were included and classified into three stages. RESULTS: Among the 66 patients recruited (63 men / 3 women, mean age 24.9 years), multiple interconnected alopecic nodules involving the vertex scalp were the main feature. Histopathology showed an extensive inflamed granulation abscess forming a dissection plane in the lower dermis/subcutis in the acute stage. Lymphocytic infiltration was predominant in seven of 21 histology specimens. Overweight and obesity were noted in 29 of 45 patients examined. No association with smoking was found. There was comorbidity with acne conglobata in 15 of 66 patients, two of whom had acne inversa. Longer disease duration and greater number of nodules were associated with higher severity of DF (p < 0.05). A complete remission rate of 25 % was achieved by any treatment, and a rate of 37.5 % was achieved with oral isotretinoin alone. CONCLUSIONS: DF is not uncommon in Taiwan. An association with obesity needs to be clarified.

Autoinflammatory Diseases in Pediatric Dermatology-Part 2: Histiocytic, Macrophage Activation, and Vasculitis Syndromes. / Enfermedades autoinflamatorias en dermatología pediátrica. Parte 2: síndromes histiocítico-macrofágicos y síndromes vasculopáticos.

The discovery of new autoinflammatory syndromes and novel mutations has advanced at breakneck speed in recent years. Part 2 of this review focuses on vasculitis syndromes and the group of histiocytic and macrophage activation syndromes. We also include a table showing the mutations associated with these autoinflammatory syndromes and treatment alternatives.

Autoinflammatory Diseases in Pediatric Dermatology-Part 1: Urticaria-like Syndromes, Pustular Syndromes, and Mucocutaneous Ulceration Syndromes. / Enfermedades autoinflamatorias en dermatología pediátrica. Parte 1: síndromes urticariformes, síndromes pustulosos y síndromes con ulceraciones cutáneo-mucosas.

Monogenic autoinflammatory diseases are a heterogeneous emergent group of conditions that are currently under intensive study. We review the etiopathogenesis of these syndromes and their principal manifestations. Our aim is to propose a classification system based on the clinicopathologic features of typical skin lesions for routine clinical use in dermatology. Our focus is on diagnosis in pediatric practice given that this is the period when the signs and symptoms of these syndromes first appear. In Part 1 we discuss the course of urticaria-like syndromes, which include cryopyrin-associated periodic conditions and hereditary periodic fever syndromes. Pustular syndromes are also covered in this part. Finally, we review the range of therapies available as well as the genetic mutations associated with these autoinflammatory diseases.

From pseudohypoparathyroidism to inactivating PTH/PTHrP signalling disorder (iPPSD), a novel classification proposed by the EuroPHP network.

OBJECTIVE: Disorders caused by impairments in the parathyroid hormone (PTH) signalling pathway are historically classified under the term pseudohypoparathyroidism (PHP), which encompasses rare, related and highly heterogeneous diseases with demonstrated (epi)genetic causes. The actual classification is based on the presence or absence of specific clinical and biochemical signs together with an in vivo response to exogenous PTH and the results of an in vitro assay to measure Gsa protein activity. However, this classification disregards other related diseases such as acrodysostosis (ACRDYS) or progressive osseous heteroplasia (POH), as well as recent findings of clinical and genetic/epigenetic background of the different subtypes. Therefore, the EuroPHP network decided to develop a new classification that encompasses all disorders with impairments in PTH and/or PTHrP cAMP-mediated pathway. DESIGN AND METHODS: Extensive review of the literature was performed. Several meetings were organised to discuss about a new, more effective and accurate way to describe disorders caused by abnormalities of the PTH/PTHrP signalling pathway. RESULTS AND CONCLUSIONS: After determining the major and minor criteria to be considered for the diagnosis of these disorders, we proposed to group them under the term 'inactivating PTH/PTHrP signalling disorder' (iPPSD). This terminology: (i) defines the common mechanism responsible for all diseases; (ii) does not require a confirmed genetic defect; (iii) avoids ambiguous terms like 'pseudo' and (iv) eliminates the clinical or molecular overlap between diseases. We believe that the use of this nomenclature and classification will facilitate the development of rationale and comprehensive international guidelines for the diagnosis and treatment of iPPSDs.

Expert Diagnosis of Plus Disease in Retinopathy of Prematurity From Computer-Based Image Analysis.

IMPORTANCE: Published definitions of plus disease in retinopathy of prematurity (ROP) reference arterial tortuosity and venous dilation within the posterior pole based on a standard published photograph. One possible explanation for limited interexpert reliability for a diagnosis of plus disease is that experts deviate from the published definitions. OBJECTIVE: To identify vascular features used by experts for diagnosis of plus disease through quantitative image analysis. DESIGN, SETTING, AND PARTICIPANTS: A computer-based image analysis system (Imaging and Informatics in ROP [i-ROP]) was developed using a set of 77 digital fundus images, and the system was designed to classify images compared with a reference standard diagnosis (RSD). System performance was analyzed as a function of the field of view (circular crops with a radius of 1-6 disc diameters) and vessel subtype (arteries only, veins only, or all vessels). Routine ROP screening was conducted from June 29, 2011, to October 14, 2014, in neonatal intensive care units at 8 academic institutions, with a subset of 73 images independently classified by 11 ROP experts for validation. The RSD was compared with the majority diagnosis of experts. MAIN OUTCOMES AND MEASURES: The primary outcome measure was the percentage of accuracy of the i-ROP system classification of plus disease, with the RSD as a function of the field of view and vessel type. Secondary outcome measures included the accuracy of the 11 experts compared with the RSD. RESULTS: Accuracy of plus disease diagnosis by the i-ROP computer-based system was highest (95%; 95% CI, 94%-95%) when it incorporated vascular tortuosity from both arteries and veins and with the widest field of view (6-disc diameter radius). Accuracy was 90% or less when using only arterial tortuosity and 85% or less using a 2- to 3-disc diameter view similar to the standard published photograph. Diagnostic accuracy of the i-ROP system (95%) was comparable to that of 11 expert physicians (mean 87%, range 79%-99%). CONCLUSIONS AND RELEVANCE: Experts in ROP appear to consider findings from beyond the posterior retina when diagnosing plus disease and consider tortuosity of both arteries and veins, in contrast with published definitions. It is feasible for a computer-based image analysis system to perform comparably with ROP experts, using manually segmented images.

The categories of cutaneous mosaicism: A proposed classification.

Mosaic disorders can most easily be studied in the skin. This article presents a comprehensive overview of the different forms of cutaneous mosaicism. Major categories are genomic versus epigenetic mosaicism and nonsegmental versus segmental mosaicism. The class of nonsegmental mosaics includes single point mosaicism as exemplified by solitary benign or malignant skin tumors; disseminated mosaicism as noted in autosomal dominant tumor syndromes such as neurofibromatosis 1; and patchy mosaicism without midline separation as found in giant melanocytic nevus. The class of segmental mosaics includes segmental manifestation of lethal genes surviving by mosaicism as noted in Proteus syndrome; type 1 segmental mosaicism of autosomal dominant skin disorders reflecting heterozygosity for a postzygotic new mutation; type 2 segmental mosaicism of autosomal dominant skin disorders reflecting loss of heterozygosity that occurred at an early developmental stage in a heterozygous embryo; and isolated or superimposed segmental mosaicism of common polygenic skin disorders such as psoriasis or atopic dermatitis. A particular form of genomic mosaicism is didymosis (twin spotting). Revertant mosaicism is recognizable as one or more areas of healthy skin in patients with epidermolysis bullosa or other serious genodermatoses. The category of epigenetic mosaicism includes several X-linked, male lethal disorders such as incontinentia pigmenti, and the patterns of lyonization as noted in X-linked non-lethal disorders such as hypohidrotic ectodermal dysplasia of the Christ-Siemens-Touraine type. An interesting field of future research will be the concept of epigenetic autosomal mosaicism that may explain some unusual cases of autosomal transmission of linear hypo- or hypermelanosis.

[New developments in hereditary blistering skin diseases]. / Neues über hereditäre, blasenbildende Hauterkrankungen.

Hereditary blistering skin diseases were described more than hundred years ago, but only the rapid scientific developments in molecular genetics in the last years have revealed the full spectrum of these diseases, delineated disease mechanisms and pointed to novel therapeutic strategies. Not only the classic forms of epidermolysis bullosa, but also new syndromic forms with multiorgan involvement, or skin fragility disorders that manifest with erosive, crusty lesions and pigment anomalies, instead of marked skin blistering belong to the group of hereditary blistering diseases. Understanding the biological functions of skin structures that provide intraepidermal and dermo-epidermal adhesion has furthered development of novel cell- and molecule-based therapies that are currently being tested in preclinical and clinical pilot trial settings.

[Important genodermatoses for the practitioner]. / Genodermatosen, die der Praktiker kennen muss.

Health or disease is a result of the genetic constellation and environmental influences. The phenotype of monogenic diseases is highly influenced by one single mutation. According to the WHO more than 10,000 monogenic diseases exist while for 1,000 diseases a molecular genetic test is available. Genodermatoses are well-documented and characterized; the most important data base for the diagnosis is the Online Mendelian Inheritance of Men data base, which can be searched in Google with the keyword "OMIM". Here genetic diseases are categorized and clinically described. We present our own epidemiologic data from the Department of Dermatology, University Hospital Basel, concerning genodermatoses. Our results show that the most common genodermatoses seen in the daily practice are porokeratoses, ichthyoses, Darier disease, neurofibromatosis and epidermolysis bullosa. They account for 91% of all genodermatoses seen in a hospital-based dermatology department of Dermatology.

[Genodermatoses for practitioners--principles and concepts]. / Genodermatosen in der täglichen Praxis - die Rolle des Dermatologen.

Every disease is a mirror of interactions between genes and the environment. In monogenic disorders only one mutation can lead to a specific phenotype. However the spectrum and the degree of manifestations depend on numerous factors from the environment. Ichthyosis vulgaris is caused by a mutation in the filaggrin gene. However the phenotype is much more pronounced in the winter months. In polygenic disorders such as atopic dermatitis numerous modifying genes influence the phenotype including a mutation in filaggrin. The skin is the organ of the human body which is most commonly involved in monogenic diseases. More than one third of all genetic diseases affect the integument. At the very moment more than 350 genodermatoses are identified with functional insights. The Human Genome Project was finished in 2001 with the aim that all genes can be identified for diagnostics, pharmacogenomics potential gene therapy and to understand the principle basis of diseases. The next project called ENCODE for Enzyclopedia of DNA Elements targets to identify all functional elements in the human genome sequence. MicroRNAs seem to have great importance for the regulation of genefunctions in the skin. At the moment epigenetics is at the epicentre of modern medicine. Epigenetics is the study of non-DNA sequence-related heredity. Epigenetics is an important tool to study the relationship between the genome and the environment. In the second part cases will be presented and the way of diagnosis making will be shown. It will be shown that it is very important to find clinical key features which may allow an allocation to a genetic pathway.

Cutaneous amyloidoses and systemic amyloidoses with cutaneous involvement.

Extracellular deposition of altered autologous protein (amyloid protein) within the dermis is the hallmark of cutaneous amyloidoses and systemic amyloidoses with cutaneous involvement. Amyloidoses may be acquired or hereditary in nature and subclassification differentiates between primary amyloidosis (no obvious predisposing disease) and secondary amyloidosis (specific underlying disease). More than 26 different proteins and peptides have been identified as amyloid precursors and these proteins are used to subclassify this heterogeneous group of diseases. The amyloid proteins show an anti-parallel beta-sheet conformation and form non-branching linear filaments of variable lengths and diameters of approximately 7.5 to 10 nm. However, the exact etiopathogenesis of amyloid formation still remains unclear. Depending on histoanatomical distribution and amount, amyloid may cause progressive and life-threatening organ dysfunction. Clinical presentation, histology, electron microscopy, and biochemical-immunological differentiation represent decisive tools for an accurate diagnosis.

[Hereditary and non-hereditary cutaneous amyloidoses]. / Hereditäre und nichthereditäre kutane Amyloidosen.

Amyloid and amyloidosis describes a heterogeneous group of diseases which are characterized by the pathological extracellular deposition of autologous proteins. Basically, amyloidoses can be divided into systemic or organ-limited (e.g. cutaneous) forms and can be acquired or hereditary in nature. The subclassification discriminates between primary amyloidosis (in the absence of an obvious predisposing disease) and secondary amyloidosis (if caused by a certain underlying disease). The subclassification of amyloidoses is based on the main protein constituent and therefore on the chemical composition of the amyloid fibrils. However, the exact etiopathogenesis of amyloid formation remains unclear. In addition to the clinical presentation, histology, electron microscopy and biochemical-immunological differentiation are also decisive for a proper diagnosis. In cutaneous amyloidosis the deposition of amyloid either occurs along reticulin fibers and the basal membrane (perireticulary amyloidoses) or along collagen fibers (pericollagenous amyloidosis). The purpose of this article is to provide an up-to-date overview on the different kinds of cutaneous amyloidoses.

Multiple unilateral skin tumors suggest type 1 segmental manifestation of familial syringoma.

An 18-year-old man presented multiple asymptomatic reddish-brown papules with a segmental distribution pattern confined to the left side of the trunk. These lesions had arisen two years before while the rest of the integument was unaffected. His further medical and family history was unremarkable. Histopathology revealed the characteristic features of syringoma. Since familial occurrence of syringoma with autosomal dominant inheritance has been described previously, we propose that the clinical phenotype observed in this patient reflects a type 1 segmental manifestation of familial syringoma and, thus, a cutaneous mosaicism.

Piecing together the puzzle of cutaneous mosaicism.

Autosomal dominant disorders of the skin may present in a pattern following the lines of embryologic development of the ectoderm. In these cases, the surrounding skin is normal, and molecular studies have shown that the causative mutation is confined to the affected ectodermal tissue (type 1 mosaicism). Rarely, an individual shows skin lesions that follow the pattern of type 1 mosaicism, but the rest of the skin shows a milder form of the disorder (type 2 mosaicism). A new study provides the molecular basis for type 2 mosaicism.

Cytogenetic and molecular evidence for cutaneous mosaicism: the ectodermal origin of Blaschko lines.

The idea that skin disorders following Blaschko lines represent genetic mosaicism is widely accepted. It seems likely that the two skin types represent the two different genotypes, but this has been remarkably difficult to prove, most studies showing a mixture of cell types in biopsies from both types of skin. Only for linear epidermolytic hyperkeratosis has it been possible to show mutant cells confined to the abnormal streaks. The hypothesis proposed here to explain this paradox is that disorders following Blaschko lines are due to mutations in genes expressed in epidermal cells (keratinocytes and melanocytes) rather than in dermal fibroblasts. The work on epidermolytic hyperkeratosis used keratinocytes, whereas most studies have used skin fibroblasts. Almost all disorders following Blaschko lines are epidermal: inflammatory, dysplastic, dyskeratotic, appendage-related, or pigmentary, and the remainder can be explained on the basis of epidermal influences on the dermis. If this hypothesis is correct, it points to a useful model system for elucidating the genetic component of common dermatoses sometimes found in Blaschko lines namely eczema, psoriasis, lichen planus, and vitiligo.