STIM1 over-activation generates a multi-systemic phenotype affecting the skeletal muscle, spleen, eye, skin, bones and immune system in mice.

Strict regulation of Ca2+ homeostasis is essential for normal cellular physiology. Store-operated Ca2+ entry (SOCE) is a major mechanism controlling basal Ca2+ levels and intracellular Ca2+ store refilling, and abnormal SOCE severely impacts on human health. Overactive SOCE results in excessive extracellular Ca2+ entry due to dominant STIM1 or ORAI1 mutations and has been associated with tubular aggregate myopathy (TAM) and Stormorken syndrome (STRMK). Both disorders are spectra of the same disease and involve muscle weakness, myalgia and cramps, and additional multi-systemic signs including miosis, bleeding diathesis, hyposplenism, dyslexia, short stature and ichthyosis. To elucidate the physiological consequences of STIM1 over-activation, we generated a murine model harboring the most common TAM/STRMK mutation and characterized the phenotype at the histological, ultrastructural, metabolic, physiological and functional level. In accordance with the clinical picture of TAM/STRMK, the Stim1R304W/+ mice manifested muscle weakness, thrombocytopenia, skin and eye anomalies and spleen dysfunction, as well as additional features not yet observed in patients such as abnormal bone architecture and immune system dysregulation. The murine muscles exhibited contraction and relaxation defects as well as dystrophic features, and functional investigations unraveled increased Ca2+ influx in myotubes. In conclusion, we provide insight into the pathophysiological effect of the STIM1 R304W mutation in different cells, tissues and organs and thereby significantly contribute to a deeper understanding of the pathomechanisms underlying TAM/STRMK and other human disorders involving aberrant Ca2+ homeostasis and affecting muscle, bones, platelets or the immune system.

Clinical and biochemical footprints of inherited metabolic diseases. VI. Metabolic dermatoses.

Cutaneous signs and symptoms may facilitate the diagnosis or can help in identifying complications or side effects of overtreatment of inherited metabolic diseases. The principal manifestations can be grouped into vascular lesions, ichthyosis, papular and nodular skin lesions, abnormal pigmentation, photosensitivity, skin laxity, hair shaft involvement, and nail abnormalities. We have summarized associations of these cutaneous signs and symptoms in 252 inherited metabolic diseases. This represents the sixth of a series of articles attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnoses according to system involvement.

Ichthyosis: A Road Model for Skin Research.

The understanding of monogenetic disorders of cornification, including the group of diseases called ichthyoses, has expanded greatly in recent years. Studies of the aetiology of more than 50 types of ichthyosis have almost invariably uncovered errors in the biosynthesis of epidermal lipids or structural proteins essential for normal skin barrier function. The barrier abnormality per se may elicit epidermal inflammation, hyperproliferation and hyperkeratosis, potentially contributing to the patient's skin symptoms. Despite this and other new knowledge about pathomechanisms, treatment of ichthyosis often remains unsatisfactory. This review highlights a series of approaches used to elucidate the pathobiology and clinical consequences of different types of ichthyosis, and related diseases with the ultimate goal of finding new and better treatments.

Molecular Genetics of Keratinization Disorders - What's New About Ichthyosis.

The heritable forms of keratinization disorders, including various forms of ichthyosis and keratodermas, comprise a phenotypically heterogeneous group of diseases which can be divided into syndromic and non-syndromic forms. In the non-syndromic forms, the clinical manifestations are limited to the cutaneous structures while the syndromic ones are associated with a spectrum of extracutaneous manifestations. The inheritance in different families can be autosomal dominant, autosomal recessive or either X-linked dominant or recessive. Currently at least 67 distinct genes have been associated with different forms of ichthyosis. These genes can be grouped on the basis of their physiological involvement, including genes encoding structural components of epidermis, those involved in epidermal lipid metabolism, or those critical for cell-cell adhesion, and keratinocyte differentiation. This overview highlights some of the recent progress made in understanding the molecular genetics of keratinization disorders, and presents selected, recently characterized cases as representative of different forms of heritable ichthyosis.

Genetics of Inherited Ichthyoses and Related Diseases.

Inherited ichthyoses are classified as Mendelian disorders of cornification (MEDOC), which are defined on the basis of clinical and genetic features and are mainly divided into non-syndromic and syndromic ichthyoses. Numerous genes, which encode for corresponding proteins, are involved in the normal differentiation of keratinocytes (cornification) and participate in the formation of a functional epidermal barrier. To date, mutations in more than 50 genes are known to result in various types of ichthyoses. Thanks to modern genetic diagnostic methods based on targeted next generation sequencing (NGS), approximately 80-90% of cases can be resolved at present. Further sequencing methods covering the whole exome (WES) or whole genome (WGS) will obviously elucidate another portion of the remaining unknown ichthyoses in the future.

Management of Ichthyosis: A Brief Review

The ichthyoses, also termed the disorders of keratinization, are a heterogenous group of skin diseases in which a distinctive horny layer arises secondary to excessive transepidermal water loss. Although occasionally acquired, the majority of ichthyoses are inherited and can be pinpointed to characteristic genetic mutations. Management depends on disease severity and includes topical agents and lifestyle modifications with or without oral retinoids. Genetic counseling is also an important consideration. This review aims to highlight advances in our understanding of disease pathogenesis as well as the holistic approach necessary to adequately manage ichthyosis patients.

More than keratitis, ichthyosis, and deafness: Multisystem effects of lethal GJB2 mutations.

BACKGROUND: Infant death in keratitis-ichthyosis-deafness (KID) syndrome is recognized; its association with specific genotypes and pathophysiology is inadequately understood. OBJECTIVE: We sought to discover characteristics that account for poor outcomes in lethal KID syndrome. METHODS: We collected 4 new cases and 9 previously reported, genotyped cases of lethal KID syndrome. We performed new molecular modeling of the lethal mutants GJB2 p.A88V and GJB2 p.G45E. RESULTS: Infant death occurred in all patients with GJB2 p.G45E and p.A88V; it is unusual with other GJB2 mutations. Early death with those 2 "lethal" mutations is likely multifactorial: during life all had ≥1 serious infection; most had poor weight gain and severe respiratory difficulties; many had additional anatomic abnormalities. Structural modeling of GJB2 p.G45E identified no impact on the salt bridge previously predicted to account for abnormal central carbon dioxide sensing of GJB2 p.A88V. LIMITATIONS: This clinical review was retrospective. CONCLUSION: GJB2 p.G45E and p.A88V are the only KID syndrome mutations associated with uniform early lethality. Those electrophysiologically severe mutations in GJB2 reveal abnormalities in many organs in lethal KID syndrome. All patients with KID syndrome may have subtle abnormalities beyond the eyes, ears, and skin. Early genotyping of KID syndrome births will inform prognostic discussion.

Dominant ELOVL1 mutation causes neurological disorder with ichthyotic keratoderma, spasticity, hypomyelination and dysmorphic features.

BACKGROUND: Ichthyosis and neurological involvement occur in relatively few known Mendelian disorders caused by mutations in genes relevant both for epidermis and neural function. OBJECTIVES: To identify the cause of a similar phenotype of ichthyotic keratoderma, spasticity, mild hypomyelination (on MRI) and dysmorphic features (IKSHD) observed in two unrelated paediatric probands without family history of disease. METHODS: Whole exome sequencing was performed in both patients. The functional effect of prioritised variant in ELOVL1 (very-long-chain fatty acids (VLCFAs) elongase) was analysed by VLCFA profiling by gas chromatography-mass spectrometry in stably transfected HEK2932 cells and in cultured patient's fibroblasts. RESULTS: Probands shared novel heterozygous ELOVL1 p.Ser165Phe mutation (de novo in one family, while in the other family, father could not be tested). In transfected cells p.Ser165Phe: (1) reduced levels of FAs C24:0-C28:0 and C26:1 with the most pronounced effect for C26:0 (P=7.8×10-6 vs HEK293 cells with wild type (wt) construct, no difference vs naïve HEK293) and (2) increased levels of C20:0 and C22:0 (P=6.3×10-7, P=1.2×10-5, for C20:0 and C22:0, respectively, comparison vs HEK293 cells with wt construct; P=2.2×10-7, P=1.9×10-4, respectively, comparison vs naïve HEK293). In skin fibroblasts, there was decrease of C26:1 (P=0.014), C28:0 (P=0.001) and increase of C20:0 (P=0.033) in the patient versus controls. There was a strong correlation (r=0.92, P=0.008) between the FAs profile of patient's fibroblasts and that of p.Ser165Phe transfected HEK293 cells. Serum levels of C20:0-C26:0 FAs were normal, but the C24:0/C22:0 ratio was decreased. CONCLUSION: The ELOVL1 p.Ser165Phe mutation is a likely cause of IKSHD.

Defining and validating a Body Skin Discomfort Index (BSDI).

OBJECTIVE: To understand the drivers of body skin discomfort and to validate a new index to assess its severity. This index should be sensitive enough to capture changes in response to treatment. METHODS: Previous consumer studies suggested seven potential main dimensions behind skin discomfort. Four of them refer to self-declarations (stinging, itching, warming and tightening), whereas three can be assessed by a dermatologist (skin dryness, redness and desquamation). Intensity and frequency or extent of these items were measured using 0-9 ordinal scales. To generate the data for validation of a new index based on the 7 items, a group of 49 subjects complaining of skin discomfort was followed up for 5 weeks: 1-week without product application to check reproducibility, followed by 4 weeks of treatment to evaluate sensitivity to change. Items not significantly reported at baseline or with changes because of treatment not sufficiently correlated with the overall change measured by the index were discarded. A control group of 49 subjects presenting no discomfort at all was also included to check the capacity of our index to discriminate both groups. The final index (Body Skin Discomfort Index, BSDI) was normalized to facilitate the clinical interpretation of the results. RESULTS: After discarding warming and skin redness, the BSDI is finally a five-dimension score calculated as follows: (TI + TF + SI + SF + ItI + ItF + DI + DE + DqI + DqE) 9 9/90 where T, S, It, D and Dq refer to tightness, stinging, itching, dryness, desquamation respectively, and I, F or E refers to intensity, frequency or extent. The final BSDI score displayed a good capacity to discriminate people with skin discomfort from people with 'normal skin', a good reproducibility (intraclass coefficient correlation ICC = 0.85) and a good sensitivity to detect change because of treatment (Difference vs. Baseline of 2.63 on a 0-9 scale). CONCLUSION: The developed index, BSDI, is a reliable way to address the measurement issue of the multidimensional skin discomfort syndrome. It thus should simplify the evaluation of cosmetic products effect and helps to compare products dedicated to body cleansing.

A practical approach to ichthyoses with systemic manifestations.

Inherited ichthyoses are rare disorders in terms of patient numbers, but abundant in terms of clinical-genetic subtypes. These disorders are often associated with severe systemic manifestations, in addition to significant medical, cosmetic and social problems. There are 17 subtypes of syndromic ichthyosis identified so far and most patients with these syndromes are living in countries with high consanguinity rates. Frequently, clinicians cannot make a definitive diagnosis and patients are not managed properly owing to the rarity and complexity of these disorders. These difficulties make this group of ichthyosis and the patients living with them 'orphan'. After skin and skin appendages, nervous system is the most frequently involved system in ichthyosis syndromes. Thus, association of ichthyosis with neurological symptoms provides an important clue for diagnosis. In this article, we aim to increase clinicians' comprehension of ichthyosis syndromes by providing a symptomatology-based approach based on this observation. Additionally, we provide a review of ichthyosis syndromes, with special emphasis on neurological symptoms, hoping to attract interest to this complicated field.

Dolichol kinase deficiency (DOLK-CDG): Two new cases and expansion of phenotype.

Congenital disorders of glycosylation (CDGs) are a group of genetic diseases caused by mutations in genes that are necessary for the addition of oligosaccharides to acceptor proteins or lipids. An early step in this process requires dolichol kinase (DK) to catalyze the formation of dolichyl phosphate, which acts as a membrane anchor for initial attachment of sugar residues that are subsequently built up to oligosaccharides and transferred to acceptor proteins and lipids for further processing. Biallelic mutations in DOLK, the gene for DK, result in human in a CDG with variable symptoms, ranging from nonsyndromic dilated cardiomypopathy to severe multiorgan involvement. We report two female siblings with novel compound heterozygous mutations in DOLK: c.951C>A (p.Tyr317Ter) and c.1558A>G (p.Thr520Ala). Both patients presented in the neonatal period with severe ichthyosis, unusual distal digital constrictions and dilated cardiomyopathy which resulted in death. Histology of the skin showed lipid droplet accumulation in the stratum corneum and keratinocytes, which suggests defective epidermal lipid metabolism. These patients represent an earlier and more severe form of DOLK-CDG (CDG-1m) with a striking presentation at birth that expands the known phenotypic spectrum.

Alu-mediated deletion of PIGL in a Patient with CHIME syndrome.

CHIME syndrome is a rare autosomal recessive neuroectodermal disorder associated with biallelic mutations in PIGL. To date, six molecularly confirmed cases of CHIME syndrome have been reported. Here, we report the seventh patient with biallelic PIGL mutations associated with CHIME syndrome and describe the first characterization of an intragenic deletion in PIGL. Our characterization of the deletion breakpoint junction demonstrated that the breakpoints occurred within Alu repeats and the deletion was most likely mediated by a microhomology event. Analysis of PIGL genomic sequences for repetitive elements demonstrated that Alu repeats represent ∼34% of its intronic sequence, suggesting that the genomic architecture may predispose the gene to disease-causing copynumber changes. Taken together, these findings indicate that patients with a clinical diagnosis of CHIME syndrome and a single identifiable mutation in PIGL warrant further investigation for copynumber changes involving PIGL.

Shwachman-Diamond syndrome presenting with early ichthyosis, associated dermal and epidermal intracellular lipid droplets, hypoglycemia, and later distinctive clinical SDS phenotype.

Shwachman-Diamond syndrome (SDS) is a recessive ribosomopathy, characterized by bone marrow failure and exocrine pancreatic insufficiency (ePI) often associated with neurodevelopmental and skeletal abnormalities. The aim of this report is to describe a SDS patient with early ichthyosis associated with dermal and epidermal intracellular lipid droplets (iLDs), hypoglycemia and later a distinctive clinical SDS phenotype. At 3 months of age, she had ichthyosis, growth retardation, and failure to thrive. She had not cytopenia. Ultrasonography (US) showed pancreatic diffuse high echogenicity. Subsequently fasting hypoketotic hypoglycemia occurred without permanent hepatomegaly or hyperlipidemia. Continuous gavage feeding was followed by clinical improvement including ichthyosis and hypoglycemia. After 14 months of age, she developed persistent neutropenia and ePI consistent with SDS. The ichthyotic skin biopsy, performed at 5 months of age, disclosed iLDs in all epidermal layers, in melanocytes, eccrine sweat glands, Schwann cells and dermal fibroblasts. These iLDs were reminiscent of those described in Dorfman-Chanarin syndrome (DCS) or Wolman's disease. Both LIPA and CGI-58 analysis did not revealed pathogenic mutation. By sequencing SBDS, a compound heterozygous for a previously reported gene mutation (c.258 + 2T>C) and a novel mutation (c.284T>G) were found. Defective SBDS may hypothetically interfere as in DCS, with neutral lipid metabolism and play a role in the SDS phenotype such as ichthyosis with dermal and epidermal iLDs and hypoglycemia. This interference with neutral lipid metabolism must most likely occur in the cytoplasm compartment as in DCS and not in the lysosomal compartment as in Wolman's disease. © 2016 Wiley Periodicals, Inc.

[Epidermal barrier - molecular structure and disorders in selected ichthyoses]. / Struktura molekularna bariery naskórkowej i jej zaburzenia w wybranych chorobach z grupy rybiej luski.

Ichthyosis is a rare, clinically heterogeneous group of 36 skin diseases with Mendelian inheritance, characterized by disorders of cornification (MeDOC, Mendelian Disorders Of Cornification). Currently there are 35 genes known which mutations are a molecular cause of different MeDOC. They encode proteins involved in the processes of keratinocytes differentiation, lipid synthesis and metabolism and DNA repair. Despite of this high molecular heterogeneity that leads to dysfunction and structure disorder of various epidermal components, the secondary effect of mutations in different genes is similar - disruption of the epidermal barrier and elevated transepidermal water loss. Disturbances in this basic epidermal protective function activate the repair mechanisms within the epidermis and lead i.a. to the primary symptom of MeDOC - hyperkeratosis. In this review we presented the current knowledge of biochemical processes and molecular causes of clinical symptoms based on selected examples of MeDOC.

Nalfurafine suppresses pruritogen- and touch-evoked scratching behavior in models of acute and chronic itch in mice.

The kappa-opioid agonist, nalfurafine, has been approved in Japan for treatment of itch in patients with chronic kidney disease. We presently investigated if systemic administration of nalfurafine inhibited ongoing or touch-evoked scratching behavior (alloknesis) following acute intradermal injection of histamine or the non-histaminergic itch mediator, chloroquine, in mice. We also investigated if nalfurafine suppressed spontaneous or touch-evoked scratching in an experimental model of chronic dry skin itch. Nalfurafine reduced scratching evoked by histamine and chloroquine. Following acute histamine, but not chloroquine, low-threshold mechanical stimuli reliably elicited directed hindlimb scratching behavior, which was significantly attenuated by nalfurafine. In mice with experimental dry skin, nalfurafine abolished spontaneous scratching but had no effect on alloknesis. Nalfurafine thus appears to be a promising treatment for acute itch as well as ongoing itch of dry skin.

Epidermal barrier in hereditary ichthyoses, atopic dermatitis, and psoriasis.

Several skin disorders are associated with impaired skin barrier function. Primary dysfunction is caused by monogenic defects in key components of the epidermis (for example ichthyoses). Secondary barrier impairment occurs in inflammatory dermatoses marked by disturbed epidermal homeostasis (eczema, psoriasis, etc.). In these disorders, inflammation impedes the synthesis or maintenance of skin barrier components. Recent evidence suggests a combination of primary and secondary barrier dysfunction in atopic dermatitis and, to a lesser extent, also in psoriasis. In the future, subtypes of atopic dermatitis may likely be defined, in which one or the other is prevalent.

Claudin-1 involved in neonatal ichthyosis sclerosing cholangitis syndrome regulates hepatic paracellular permeability.

UNLABELLED: Neonatal ichthyosis and sclerosing cholangitis (NISCH) syndrome is a liver disease caused by mutations of CLDN1 encoding Claudin-1, a tight-junction (TJ) protein. In this syndrome, it is speculated that cholestasis is caused by Claudin-1 absence, leading to increased paracellular permeability and liver injuries secondary to paracellular bile regurgitation. We studied the role of claudin-1 in hepatic paracellular permeability. A NISCH liver and polarized rat cell lines forming TJs, the hepatocellular Can 10 and the cholangiocellular normal rat choloangiocyte (NRC), were used. In contrast to NRC, Can 10 does not express claudin-1. Can 10 cells were transfected with a plasmid encoding Claudin-1, and stable Claudin-1-expressing clones were isolated. Claudin-1 expression was silenced by transfection with short interfering RNA in Can 10 clones and with short hairpin RNA in NRC. Claudin-1 expression was evaluated by quantitative reverse-transcriptase polymerase chain reaction, immunoblotting, and immunolocalization. Paracellular permeability was assessed by fluorescein isothiocyanate-dextran passage in both lines and by transepithelial resistance measurements in NRC. In the NISCH liver, Claudin-1 was not detected in hepatocytes or cholangiocytes. In Claudin-1 expressing Can 10 clones, Claudin-1 was localized at the TJ and paracellular permeability was decreased, compared to parental Can 10 cells, this decrease correlating with claudin-1 levels. Silencing of Claudin-1 in Can 10 clones increased paracellular permeability to a level similar to that of parental cells. Similarly, we observed an increase of paracellular permeability in NRC cells silenced for claudin-1 expression. CONCLUSION: Defect in claudin-1 expression increases paracellular permeability in polarized hepatic cell lines, supporting the hypothesis that paracellular bile leakage through deficient TJs is involved in liver pathology observed in NISCH syndrome.

[Diagnostics of keratitis-ichthyosis-deafness syndrome (KID- syndrome)].

The combination of pre-lingual and sensorinerual deafness with skin hyperkeratinization is a relatively rare pathology. Only 11 families affected by this disorder were described in the literature during the last 30 years (from 1975 to 2002). To date, there are no more than 50 cases of this condition known in the world. Modern molecular methods revealed in all such patients a mutation in the GJB2 gene as the primary cause of the disease. We studied a 4 year-old girl with bilateral congenital grade IV sensorineural deafness. Her unusual appearance drew attention aas early as the primary examination; the patient had the deep-set eyes and dry skin over the entire body, she presented with hypotrichosis of the scalp, thin and light-blond hair. Analysis of the nucleotide sequence of the GJB2 gene revealed the substitution of guanine-148 by adenine that led to D50N amino acid substitution. This dominant mutation proved to be the cause of keratitis-ichthyosis-deafness syndrome (KID-syndrome). A review of the literature concerning molecular diagnostics and clinical features of this syndrome is presented. The results of molecular-genetic investigations provided the data on pathogenesis of different variants of sensorineural deafness and the associated genotype-phenotype relationships that may be used as a basis for the further development of the methods for the prevention and treatment of KID-syndrome.

Drosophila spichthyin inhibits BMP signaling and regulates synaptic growth and axonal microtubules.

To understand the functions of NIPA1, mutated in the neurodegenerative disease hereditary spastic paraplegia, and of ichthyin, mutated in autosomal recessive congenital ichthyosis, we have studied their Drosophila melanogaster ortholog, spichthyin (Spict). Spict is found on early endosomes. Loss of Spict leads to upregulation of bone morphogenetic protein (BMP) signaling and expansion of the neuromuscular junction. BMP signaling is also necessary for a normal microtubule cytoskeleton and axonal transport; analysis of loss- and gain-of-function phenotypes indicate that Spict may antagonize this function of BMP signaling. Spict interacts with BMP receptors and promotes their internalization from the plasma membrane, implying that it inhibits BMP signaling by regulating BMP receptor traffic. This is the first demonstration of a role for a hereditary spastic paraplegia protein or ichthyin family member in a specific signaling pathway, and implies disease mechanisms for hereditary spastic paraplegia that involve dependence of the microtubule cytoskeleton on BMP signaling.