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.

X-Linked Familial Focal Epilepsy Associated With Xp22.31 Deletion.

BACKGROUND: The genetic basis for familial focal epilepsy is poorly understood, with most of the known genetic causes occurring via autosomal dominant inheritance. X-linked familial focal epilepsy has not been previously reported. METHODS: We reviewed our research database for cases of X-linked focal epilepsy. RESULTS: We identified three boys with X-linked ichthyosis and focal epilepsy, including two maternal cousins. Age of seizure onset ranged from seven to 10 years, and all three patients had seizures that were relatively easily controlled. The epilepsy phenotype in all boys was consistent with self-limited focal epilepsy of childhood, most closely resembling childhood epilepsy with centrotemporal spikes. Brain magnetic resonance imaging was normal in two of the boys, with a third found to have a suspected focal cortical dysplasia. All three boys carried maternally inherited hemizygous Xp22.31 deletions (estimated size 0.9 to 1.66 Mb), affecting four to six genes. Of the affected genes, only STS has clear clinical relevance; deletions, and pathogenic variants in STS cause X-linked ichthyosis, although all patients described had only minor skin findings. CONCLUSIONS: The findings in these patients illustrate that X-linked familial focal epilepsy can occur, although it is a rare entity. Although STS pathogenic variants are likely better categorized as an epilepsy risk factor, variants in this gene may partially explain the male predominance observed in specific epilepsy phenotypes, namely childhood epilepsy with centrotemporal spikes.

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.

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.

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.

Biotinidase deficiency in a newborn.

INTRODUCTION: Biotinidase deficiency is an inherited disorder of biotin metabolism that is untreated may present within the first few month of life. OBJECTIVE: We report the exceptional observation of a biotinidase deficiency in Morocco. The rarity of this pathology, its age of onset, its mode of revelation and the lack of treatment in Morocco make the particularity of this observation. OBSERVATION: A newborn child born from a 24-year-old mother, followed by an estimated pregnancy of 37 weeks of amenorrhea according to the Farr score (morphological maturation score used for the dating of the pregnancy term). The infant presented at 7 days of life with a cutaneous-mucous eruption with icithiosic dry erythroderma of interest to the trunk, the face, the scalp associated with alopecia and depilation of the eyebrow. The biotinoidase deficiency was confirmed by its low serum concentration at 49 nka / l. The newborn died at 20 days of life before starting the specific treatment. CONCLUSION: Biotinidase deficiency is a rare condition requiring early screening and rapid management. The delay in diagnosis and the unavailability of treatment in Morocco can have fatal consequences.

Non-invasive methods for evaluation of skin manifestations in patients with ichthyosis.

Hereditary ichthyoses include a group of diseases characterized by hyperkeratosis, scaling, generalized xerosis, and is frequently associated with erythroderma. They are classified as syndromic and non-syndromic entities. The monitoring of the severity of ichthyosis requires different strategies for immediate analysis, which can comprise visual analogue scales or non-invasive quantitative methods, which collect information on disease progression that may contribute to the management of ichthyosis and aid in delineating clinical trials. In this article, we present a comprehensive review of the existing visual analogue scales, their validation, and their use in studies of disease severity and clinical trials. Interestingly, after many years of study, to date there is not a unanimously accepted tool for assessing the harshness of clinical features. Therefore, we discuss the perspectives of some non-invasive quantitative methods and strategies employed in clinical studies performed in patients with ichthyosis. Advances in these methods provide a rationale of their potential application in the evaluation of ichthyosis severity. Our purpose is to show an overview of non-invasive methodologies for the study of the harshness of ichthyosis.

Pharmacological treatments for cutaneous manifestations of inherited ichthyoses.

Inherited ichthyoses are a group of etiologically heterogeneous diseases that affect the function of the skin and that are classified as syndromic and non-syndromic entities. Irrespective of the type, all these disorders are generally produced by mutations in genes involved in a variety of cellular functions in the skin. These mutations lead to disruption of the stratum corneum and impairment of the skin barrier, producing clinical features such as hyperkeratosis, skin scaling, erythema, fissures, pruritus, inflammation, and skin pain. Despite advances in the knowledge of the pathogenesis of ichthyoses, there is, to our knowledge, no definitive cure for skin manifestations, and current treatments consist of moisturizers, emollients, and keratolytic agents. In this respect, the development of new formulations based on nanotechnology could be useful to enhance their therapeutic effectiveness. In this article, we provide a comprehensive description of pharmacological treatments for cutaneous manifestations in patients with inherited ichthyosis and discuss novel approaches with therapeutic potential for this purpose. Moreover, we offer an overview of toxicity concerns related to these treatments.

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.

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.

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.

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.

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.

Establishing and Validating an Ichthyosis Severity Index.

We designed and validated a Visual Index for Ichthyosis Severity for scale and erythema that provides (1) written descriptions of the features characteristic of each level of severity, (2) visual standards for four body sites, and (3) two distinct standards to account for different types of scale. We tested the Visual Index for Ichthyosis Severity for reliability and reproducibility using two different settings: one that utilized scoring of 60 test photographs by 10 dermatologists, and one with in-person evaluations on 85 subjects by 12 dermatologists at the Foundation for Ichthyosis and Related Skin Types conference. The validation process revealed high reliability and reproducibility for both scale and erythema. The interrater and intrarater intraclass correlation coefficients for scale were consistently near or greater than 0.7 in both settings. By contrast, the interrater reliability for erythema was higher during in-person validation compared with validation on test photographs. Our analysis indicates that the Visual Index for Ichthyosis Severity performs better in person than with photographs, an important consideration in the design of clinical trials. Power analysis predicts that a 1-point difference on this 5-step scale would be detectable with 12 subjects in each of two defined groups. This index provides a tool for clinical phenotyping and assessment of therapeutic response for many disorders of keratinization.

[Collodion baby: clinical aspects and role of prenatal diagnosis]. / Le bébé collodion: aspects cliniques et intérêt du diagnostic anténatal.

Collodion baby is a severe form of congenital ichthyosis detected in neonatal period. It often has a characteristic clinical picture. When evolution is not fatal; it often causes dry Ichthyosis. Thanks to molecular biology techniques, prenatal diagnosis can be made since the 10-12 weeks of amenorrhea, allowing genetic counselling. Prognosis depends on several parameters, namely the degree of the initial manifestation, the duration of desquamation, as well as underlying Ichthyosis This rewiew of the literature which aims to clarify the diagnostic aspects and therapeutic treatment as well as the role of the antenatal diagnosis is based on a new observation of a collodion baby born at 34 weeks, of a parturient woman having an index case and of infant deaths occurring in the first day of life.

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.

A homozygous FITM2 mutation causes a deafness-dystonia syndrome with motor regression and signs of ichthyosis and sensory neuropathy.

A consanguineous family from Pakistan was ascertained to have a novel deafness-dystonia syndrome with motor regression, ichthyosis-like features and signs of sensory neuropathy. By applying a combined strategy of linkage analysis and whole-exome sequencing in the presented family, a homozygous nonsense mutation, c.4G>T (p.Glu2*), in FITM2 was identified. FITM2 and its paralog FITM1 constitute an evolutionary conserved protein family involved in partitioning of triglycerides into cellular lipid droplets. Despite the role of FITM2 in neutral lipid storage and metabolism, no indications for lipodystrophy were observed in the affected individuals. In order to obtain independent evidence for the involvement of FITM2 in the human pathology, downregulation of the single Fitm ortholog, CG10671, in Drosophila melanogaster was pursued using RNA interference. Characteristics of the syndrome, including progressive locomotor impairment, hearing loss and disturbed sensory functions, were recapitulated in Drosophila, which supports the causative nature of the FITM2 mutation. Mutation-based genetic counseling can now be provided to the family and insight is obtained into the potential impact of genetic variation in FITM2.

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.