The spectrum of pathogenic mutations in SPINK5 in 19 families with Netherton syndrome: implications for mutation detection and first case of prenatal diagnosis

Two Incidental Sibling Diagnoses of Netherton Syndrome in Separate Visits: A Case Report

Netherton syndrome (NTS) is a genetic disorder that predominantly affects the hair and the skin, and it can have a wide variety of presentations. The genetic syndrome is more common with consanguineous parents. Given the rarity and varying presentation of the condition, a few cases have been reported in the literature. We present an unusual case of two incidental diagnoses of NTS in siblings of consanguineous parents, manifesting as erythroderma and other symptoms that were initially diagnosed as pityriasis rubra pilaris and psoriasis in separate visits. Physicians must maintain a high index of suspicion when faced with chronic skin conditions and hair shaft abnormalities that may have been present since childhood to avoid the sequela of inadvertent prolonged or misdiagnosis.

Congenital Ichthyosis: Current Approaches to Prenatal Diagnoses

INTRODUCTION

Congenital ichthyosis represents a wide spectrum of diseases. This article reviews prenatal testing for ichthyosis.

METHODS

We used pubmed.ncbi.nlm.nih.gov to search for 38 types of congenital ichthyosis combined with 17 words related to prenatal testing.

RESULTS

Search resulted in 408 publications covering 13 types of ichthyoses and four types of tests.

DISCUSSION

Biochemical testing is diagnostic in trichothiodystrophy, but nonspecific in X-linked ichthyosis and Refsum syndrome. Except in X-linked ichthyosis, biochemical testing requires invasive procedures to obtain fetal skin biopsy, amniocytes, or chorionic villus samples. It is superior to histological and cytological examination of fetal skin biopsy or amniocytes because keratinization occurs later in pregnancy and microscopy cannot differentiate between ichthyosis types. Imaging is more acceptable due to noninvasiveness and routine use, although ultrasonography is operator-dependent, nonspecific, and captures abnormalities at late stage. Molecular tests are described in at-risk pregnancies but testing of free fetal DNA was not described.

Netherton syndrome in a Bulgarian patient : Presentation of a case and an update of therapeutic options

Comel-Netherton syndrome, or Netherton syndrome (NS), is a rare chronic genetic skin condition affecting the daily life of patients, which often results in poorly developed social skills and anxiety. Genetic predisposition plays a key role alongside the clinical findings, and clinicians must be aware of it as it can mimic other well-known skin conditions. Diagnosis is challenging both clinically and histologically. Clinically, it can mimic a severe form of atopic dermatitis, psoriasiform dermatitis overlapping with atopic dermatitis, or erythrokeratodermia variabilis. The difficulties in making histological diagnosis are similar, and it is often necessary to take several biopsies in order to clarify the diagnosis. Although retinoids are used for both psoriasis, erythrokeratodermia variabilis, and other congenital forms of keratodermia, the recommended treatment doses are different. This often results in poor treatment outcome. We present a 16-year-old patient previously diagnosed as erythrokeratodermia variabilis and treated with little to no improvement. Systemic therapy with acitretin 10 mg daily, local pimecrolimus 1%, emollients, and bilastine 20 mg once daily was initiated. Due to the limited application of retinoids and the difficulties in achieving permanent remission, modern medicine is faced with the challenge of seeking innovative therapeutic solutions. New hopes are placed on targeted or anti-cytokine therapy, based on inhibiting the inflammatory component of the disease. This article is mainly focused on innovative therapeutic options, including modern medications such as dupilumab, infliximab, secukinumab, anakinra, omalizumab, and others.

Netherton Syndrome Caused by Heterozygous Frameshift Mutation Combined with Homozygous c.1258A>G Polymorphism in SPINK5 Gene

Netherton syndrome (NS) is a rare autosomal recessive disorder caused by SPINK5 mutations, resulting in a deficiency in its processed protein LEKTI. It is clinically characterized by the triad of congenital ichthyosis, atopic diathesis, and hair shaft abnormalities. The SPINK5 (NM_006846.4): c.1258A>G polymorphism (rs2303067) shows a significant association with atopy and atopic dermatitis (AD), which share several clinical features with NS. We describe an NS patient, initially misdiagnosed with severe AD, who carried the heterozygous frameshift (null) mutation (NM_006846.4): c.957_960dup combined with homozygous rs2303067 in the SPINK5 gene. Histopathological examination confirmed the diagnosis, whereas an immunohistochemical study showed normal epidermal expression of LEKTI, despite the genetic findings. Our results corroborate the hypothesis that haploinsufficiency of SPINK5, in the presence of a SPINK5 null heterozygous mutation in combination with homozygous SPINK5 rs2303067 polymorphism, can be causative of an NS phenotype, impairing the function of LEKTI despite its normal expression. Due to the clinical overlap between NS and AD, we suggest performing SPINK5 genetic testing to search for the SPINK5 (NM_006846.4): c.1258A>G polymorphism (rs2303067) and ensure a correct diagnosis, mainly in doubtful cases.

Clinical and genetic characterization of Netherton syndrome due to SPINK5 founder variant in Latvian population

OBJECTIVE

Netherton syndrome (NS) (OMIM:256500) is a very rare autosomal recessive multisystem disorder mostly affecting ectodermal derivatives (skin and hair) and immune system. It is caused by biallelic loss-of-function variants in the SPINK5 gene, encoding the protease inhibitor lymphoepithelial Kazal-type-related inhibitor (LEKTI).

MATERIAL, METHODS AND RESULTS

Here, we describe NS clinical and genetic features of homogenous patient group: 9 individuals from 7 families with similar ethnic background and who have the same SPINK5 variant (NM_006846.4: c.1048C > T, p.(Arg350*)) in homozygous or compound heterozygous states, suggesting that it is a common founder variant in Latvian population. Indeed, we were able to show that the variant is common in general Latvian population, and it shares the same haplotype among the NS individual. It is estimated that the variant arose >1000 years ago. Clinically, all nine patients exhibited typical NS skin changes (scaly erythroderma, ichthyosis linearis circumflexa, itchy skin), except for one patient who has a different skin manifestation-epidermodysplasia. Additionally, we show that developmental delay, previously underrecognized in NS, is a common feature among these patients.

CONCLUSIONS

This study shows that the phenotype of NS individuals with the same genotype is highly homogeneous.

Ustekinumab therapy for Netherton syndrome

Netherton syndrome (NS) is a rare disorder of cornification associated with high morbidity. It is caused by bi-allelic mutations in SPINK5 encoding the serine protease inhibitor LEKTI. Previous studies have shown Th17 skewing with IL-23 upregulation in NS, raising the possibility that targeting these inflammatory pathways may alleviate disease manifestations. We ascertained the therapeutic efficacy of six doses of ustekinumab administered to three patients with NS over a period of 13 months using the Ichthyosis Area and Severity Index (IASI), the Dermatology Life Quality Index (DLQI), a visual analogue scale (VAS) for itch and the peak-pruritus numeric rating scale (PP-NRS). Histopathology analysis including CD3, CD4, CD8 and interleukin 17 (IL-17) immunostaining, was performed at baseline and 4 weeks following the last ustekinumab dose. Total IASI scores were reduced by 28% in two patients at week 16 with sustained response by week 56. No consistent improvement in DLQI, VAS for itch and PP-NRS scores was observed. The inflammatory infiltrate and the degree of acanthosis were slightly reduced at week 56 as compared to baseline. No significant change in immunostaining of the various inflammatory markers was observed at week 56. In conclusion, this case series did not demonstrate a significant therapeutic effect of ustekinumab in NS.

A global, cross-sectional survey of patient-reported outcomes, disease burden, and quality of life in epidermolysis bullosa simplex

BACKGROUND

Epidermolysis bullosa simplex (EBS) comprises a group of rare, blistering genodermatoses. Prior work has been limited by small sample sizes, and much remains unexplored about the disease burden and health-related quality of life (QOL) of patients with EBS. The aim of this study was to characterize the most common patient-reported clinical manifestations and the health-related impact of QOL in EBS, and to examine differences in disease burden by age.

METHODS

Patients with a diagnosis of epidermolysis bullosa (EB) or their caregivers completed a one-time online survey administered by EBCare, an international online EB registry. Survey data from respondents self-reporting a diagnosis of EBS were analyzed for clinical and wound manifestations, medication use, and QOL (using Quality of Life in Epidermolysis Bullosa [QOLEB] scores). Differences across age groups were assessed using Kruskal-Wallis and Fisher's exact tests.

RESULTS

There were 214 survey respondents with EBS. The mean age was 32.8 years (standard deviation = 19.2). Many respondents reported blisters (93%), recurrent wounds (89%), pain (74%), chronic wounds (59%), itch (55%), and difficulty walking (44%). Mean QOLEB score was 14.7 (standard deviation = 7.5) indicating a "moderate" impact on QOL, and 12% of respondents required regular use of opiates. Findings were consistent in subgroup analyses restricted to respondents with diagnostic confirmation via genetic testing or skin biopsy (n = 63 of 214). Age-stratified analyses revealed differences in disease burden: younger respondents were more likely to self-report severe disease (24% vs. 19% vs. 5% for respondents aged 0-9 vs. 10-17 vs. 18 + , p = 0.001), failure to thrive (9% vs. 15% vs. 3%, p = 0.02), and use of gastrostomy tubes (15% vs. 12% vs. 1%, p < 0.001) and topical antibiotics (67% vs. 69% vs. 34%, p < 0.001), while older respondents were more likely to be overweight or obese (6% vs. 0% vs. 51%, p < 0.001) and have difficulty walking (24% vs. 46% vs. 48%, p = 0.04).

CONCLUSIONS

In the largest international cross-sectional survey of EBS patients conducted, respondents reported extensive disease burden including significant wounding, pain, itch, difficulty walking, and impact on QOL. Age stratified disease manifestations. These findings suggest significant unmet need, and treatment and counseling for EBS patients should consider age-specific differences.

Netherton syndrome plus atopic dermatitis: Two new genetic mutations in the same patient

A child who comes to our attention for the appearance of erythematous, scaly lesions localized to the upper and lower limbs for 2 months. Histological features suggested ichthyosiform disease and concomitant mutations in the SPINK5 and FLG2 genes confirmed Netherton syndrome with severe atopic manifestations.

Pili Torti: A Feature of Numerous Congenital and Acquired Conditions

Pili torti is a rare condition characterized by the presence of the hair shaft, which is flattened at irregular intervals and twisted 180° along its long axis. It is a form of hair shaft disorder with increased fragility. The condition is classified into inherited and acquired. Inherited forms may be either isolated or associated with numerous genetic diseases or syndromes (e.g., Menkes disease, Björnstad syndrome, Netherton syndrome, and Bazex-Dupré-Christol syndrome). Moreover, pili torti may be a feature of various ectodermal dysplasias (such as Rapp-Hodgkin syndrome and Ankyloblepharon-ectodermal defects-cleft lip/palate syndrome). Acquired pili torti was described in numerous forms of alopecia (e.g., lichen planopilaris, discoid lupus erythematosus, dissecting cellulitis, folliculitis decalvans, alopecia areata) as well as neoplastic and systemic diseases (such as cutaneous T-cell lymphoma, scalp metastasis of breast cancer, anorexia nervosa, malnutrition, cataracts, and chronic graft-vs.-host disease). The condition may also be induced by several drugs (epidermal growth factor receptor inhibitors, oral retinoids, sodium valproate, and carbamide perhydrate). The diagnosis of pili torti is based on trichoscopic or microscopic examination. As pili torti is a marker of numerous congenital and acquired disorders, in every case, the search for the signs of underlying conditions is recommended.

A novel SPINK5 donor splice site variant in a child with Netherton syndrome

BACKGROUND

Netherton syndrome (NS) is a genodermatosis caused by loss-of-function mutations in SPINK5, resulting in aberrant LEKTI expression.

METHOD

Next-generation sequencing of SPINK5 (NM_001127698.1) was carried out and functional studies were performed by immunofluorescence microscopy of a lesional skin biopsy using anti-LEKTI antibodies.

RESULTS

We describe a novel SPINK5 likely pathogenic donor splice site variant (NM_001127698.1:c.2015+5G>A) in a patient with NS and confirm its functional significance by demonstrating complete loss of LEKTI expression in lesional skin by immunofluorescence analysis.

CONCLUSION

The 2015+5G>A is a novel, likely pathogenic variant in NS. Herein we review and assimilate documented SPINK5 pathogenic variants and discuss possible genotype-phenotype associations in NS.

Netherton syndrome caused by compound heterozygous mutation, c.80A>G mutation in SPINK5 and large-sized genomic deletion mutation, and successful treatment of intravenous immunoglobulin

Background

Netherton syndrome (NS) is an autosomal recessive disorder due to mutations in the SPINK5 gene. Here, we report the first case of NS caused by a large genomic deletion.

Methods

We present the clinical data of a 3‐year‐old Chinese boy who was initially misdiagnosed with severe atopic dermatitis. Subsequently, the patient presented with typical ichthyosis linearis circumflexa and had representative hair shaft of trichorrhexis invaginate, which alerted the physician of the high possibility of NS. A genomic DNA sample was extracted from peripheral blood and whole‐exome sequencing (WES) was performed. Sanger sequencing and quantitative real‐time polymerase chain reaction (qRT‐PCR) were performed to verify the mutation and genomic deletion, respectively, in the pedigree.

Results

WES revealed compound heterozygous mutations in SPINK5, including a c.80A>G mutation and a ~275 Kb‐sized genomic deletion (chr5:147443576‐147719312). The c.80A>G mutation was verified by Sanger sequencing in the pedigree. The father had the same heterozygous mutation; however, the mutation was absent in the proband's mother. The qRT‐PCR results identified a large deletion (chr5:147444834‐147445034) in SPINK5 in the proband and his mother. The eruptions improved remarkably after intravenous immunoglobulin (IVIG) therapy.

Conclusions

This is the first observation of NS caused by a large deletion. Our findings have important implications for mutation screening and genetic counseling in NS. Our report also verifies and supports the safety and efficacy of IVIG therapy in patients with NS.

The challenging management of a series of 43 infants with Netherton syndrome: unexpected complications and novel mutations

BACKGROUND

Netherton syndrome (NS) is a rare disease caused by SPINK5 mutations, featuring variable skin and hair involvement and, in many cases, allergic manifestations with a risk of lethality, particularly in infants. The clinical management of NS is challenging.

OBJECTIVES

To analyse the clinical manifestations of a cohort of infants with NS managed in a reference centre and to draw up recommendations for management.

METHODS

We conducted a monocentric analysis of patients with NS. The inclusion criteria were management in our reference centre, a histologically or molecularly confirmed diagnosis of NS and available epidemiological, clinical and laboratory data.

RESULTS

A total of 43 patients with NS were included. Hypernatraemia was reported in 23 cases (54%) and associated with a greater likelihood of enteral and/or parenteral nutritional support (P < 0.001). Moreover, hypernatraemia was more frequent in patients with skin manifestations at birth (P = 0.026) and in patients bearing the c.153delT mutation in SPINK5 exon 3 (P = 0.014). The need for enteral and/or parenteral nutritional support was associated with a history of hypernatraemic dehydration (P < 0.001). Several unexpected extracutaneous complications were recorded, and new mutations were reported. The death rate (9% overall) was higher among the subset of patients bearing the c.153delT deletion.

CONCLUSIONS

Our data emphasize that neonatal NS is a severe and sometimes lethal multisystem disorder. Patients have a high risk of variable metabolic anomalies (i.e. lethal hypernatraemia) and therefore have major nutritional needs. Cases of NS associated with c.153delT are particularly severe. Unexpected clinical manifestations broadened the phenotypic spectrum of NS. We provide recommendations on the management of the life-threatening manifestations of NS in neonates based on our multidisciplinary experience.

Genetic polymorphisms in serine protease inhibitor Kazal-type 5 and risk of atopic dermatitis: A meta-analysis

BACKGROUND

This study aimed to investigate the role of serine protease inhibitor Kazal-type 5 (SPINK5) polymorphisms (Asn368Ser, Asp386Asn and Glu420Lys) and the risk of atopic dermatitis (AD).

METHODS

Studies associated with SPINK5 mutations and AD risk were searched from three databases, including PubMed, Embase, and Cochrane library, with a retrieval deadline of April 22, 2019. An odds ratio (OR) with a 95% confidence interval (95% CI) was chosen as the effect size. Egger's linear regression test was enrolled to assess the level of publication bias.

RESULTS

Overall, 6 studies met the inclusion criteria for meta-analysis. Significantly statistical differences were calculated between patients with AD and healthy individuals on Asn368Ser polymorphism in the allele model (G vs A: OR = 1.2643, 95% CI = 1.0666-1.4987, P = .0069), co-dominant model (GG vs AA: OR = 1.6609, 95% CI = 1.1736-2.3505, P = .0042; GA vs AA: OR = 1.5448, 95% CI = 1.1263-2.1189, P = .0070), and dominant model (GG+GA vs AA: OR = 1.5700, 95% CI = 1.1656-2.1146, P = .0030). However, no statistically significant difference was found in the recessive model for Asn368Ser and other genetic models for Asp386Asn and Glu420Lys (all P > .05). No significant publication bias was found.

CONCLUSION

The SPINK5 Asn368Ser polymorphism may be a risk factor for AD.

Netherton's Syndrome: A Case of Two Male Siblings Diagnosed in Adulthood

Netherton's syndrome (NS) is a rare autosomal recessive genetic disease caused by a germline mutation in the SPINK5 gene. It is most commonly diagnosed in neonates due to the presence of congenital ichthyosiform erythroderma. Affected individuals will typically also develop a hair shaft abnormality known as trichorrhexis invaginata, severe atopy, and a migratory rash known as ichythyosis linearis circumflexa. The chronicity and severity of NS adversely affects a patient's quality of life to a large extent. It Is therefore important that this condition is identified early, and treatment to reduce cutaneous inflammation is initiated in a timely fashion. However, due to this condition being relatively rare, a lack of awareness may lead clinicians to misdiagnose it as atopic dermatitis or undifferentiated psoriasis. Clinicians should therefore be aware of the peripheral stigmata that this disease may present as in adulthood, so that a correct diagnosis can be made if it was previously missed. Here we present a case of two male siblings from Jordon who were misdiagnosed since childhood as having erythrodermic psoriasis. Clinical examination of one of the siblings, as an adult, revealed multiple peripheral features associated with NS. Genetic analysis through sanger sequencing was also able to identify a mutation in the SPINK5 gene, confirming the diagnosis.

Management of congenital ichthyoses: European guidelines of care, part two

These guidelines for the management of congenital ichthyoses have been developed by a multidisciplinary group of European experts following a systematic review of the current literature, an expert conference held in Toulouse in 2016, and a consensus on the discussions. These guidelines summarize evidence and expert-based recommendations and intend to help clinicians with the management of these rare and often complex diseases. These guidelines comprise two sections. This is part two, covering the management of complications and the particularities of some forms of congenital ichthyosis.

Is c.1431-12G>A A common European mutation of SPINK5? report of a patient with Netherton Syndrome

Netherton Syndrome (NS) is a very rare genetic skin disease resulting from defects in the SPINK5 gene (encoding the protease inhibitor lympho-epithelial Kazal type inhibitor 1, LEKTI1). In this report, we provide a detailed clinical description of a Polish patient with two SPINK5 mutations, the novel c.1816_1820+21delinsCT and possibly recurrent c.1431-12G>A. A detailed pathogenesis of Netherton Syndrome, on the basis of literature review, is discussed in the view of current knowledge about the LEKT1 molecular processing and activity.

Role of molecular testing in the multidisciplinary diagnostic approach of ichthyosis

Background

The term ichthyosis describes a generalized disorder of cornification characterized by scaling and/or hyperkeratosis of different skin regions. Mutations in a broad group of genes related to keratinocyte differentiation and epidermal barrier function have been demonstrated to play a causative role in disease development. Ichthyosis may be classified in syndromic or non-syndromic forms based on the occurrence or absence of extracutaneous signs. In this setting, the diagnosis of ichthyosis is an integrated multistep process requiring a multidisciplinary approach in order to formulate the appropriate diagnostic hypothesis and to address the genetic testing.

Methods

Due to the complex features of the different ichthyoses and the high number of genes involved we have investigated a group of 64 patients, affected by syndromic and non-syndromic diseases, using Next Generation Sequencing as a new tool for the molecular diagnosis.

Results

Using this innovative molecular approach we were able to find pathogenic mutations in 53 out of 64 patients resulting in 82.8 % total detection rate. An interesting result from the analysis of the data is the high rate of novel sequence variations found compared to known mutations and the relevant rate of homozygous mutations.

Conclusions

The possibility to analyze a large number of genes associated with various diseases allows to study cases with phenotypes not well-determined, giving the opportunity to make new genotype-phenotype correlation. In some cases there were discrepancies between clinical features and histology or electron microscopy and only molecular analysis allowed to definitively resolve the diagnostic dilemma. The genetic diagnosis of ichthyosis leads to a more accurate and effective genetic counseling, allowing correct evaluation of the risk of recurrence, particularly in families with consanguineous background.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-016-0384-4) contains supplementary material, which is available to authorized users.

Nucleic acid delivery into skin for the treatment of skin disease: Proofs-of-concept, potential impact, and remaining challenges

Nucleic acids (NAs) hold significant potential for the treatment of several diseases. Topical delivery of NAs for the treatment of skin diseases is especially advantageous since it bypasses the challenges associated with systemic administration which suffers from enzymatic degradation, systemic toxicity and lack of targeting to skin. However, the skin's protective barrier function limits the delivery of NAs into skin after topical application. Here, we highlight strategies for enhancing delivery of NAs into skin, and provide evidence that translation of topical NA therapies could have a transformative impact on the treatment of skin diseases.

Netherton Syndrome in a Neonate with Possible Growth Hormone Deficiency and Transient Hyperaldosteronism

Netherton syndrome, a rare autosomal recessive genetic disorder, is classified as an ichthyosiform syndrome. In this report we present the case of a neonate with erythroderma shortly after birth, accompanied by severe hypernatremia, recurrent infections, transient hyperaldosteronism, and signs of growth hormone (GH) deficiency. DNA molecular analysis in the SPINK5 gene revealed heterozygosity in our index patient for 238insG and 2468delA frameshift mutations in exons 4 and 26, respectively, in the maternal allele and 1431-12G>A splice-site mutation in intron 15 in the paternal allele as well as the missense variation E420K in homozygous state. Combination of the identified mutations along with transient hyperaldosteronism and possible GH deficiency have not been described before. Accordingly, the importance of early multidisciplinary approach is highlighted, in order to reach accurate diagnosis, initiate prompt treatment, and ensure survival with fewer disease complications.

Cellular basis of secondary infections and impaired desquamation in certain inherited ichthyoses

IMPORTANCE

Secondary infections and impaired desquamation complicate certain inherited ichthyoses, but their cellular basis remains unknown. In healthy human epidermis, the antimicrobial peptides cathelicidin (LL-37) and human β-defensin 2 (HBD2), as well as the desquamatory protease kallikrein-related peptidase 7 (KLK7), are delivered to the stratum corneum (SC) interstices by lamellar body (LB) exocytosis.

OBJECTIVE

To assess whether abnormalities in the LB secretory system could account for increased risk of infections and impaired desquamation in inherited ichthyoses with known abnormalities in LB assembly (Harlequin ichthyosis [HI]), secretion (epidermolytic ichthyosis [EI]), or postsecretory proteolysis (Netherton syndrome [NS]).

DESIGN, SETTING, AND PARTICIPANTS

Samples from library material were taken from patients with HI, EI, NS, and other ichthyoses, but with a normal LB secretory system, and in healthy controls and were evaluated by electron microscopy and immunohistochemical analysis from July 1, 2010, through March 31, 2013.

MAIN OUTCOME AND MEASURES

Changes in LB secretion and in the fate of LB-derived enzymes and antimicrobial peptides in ichthyotic patients vs healthy controls.

RESULTS

In healthy controls and patients with X-linked ichthyosis, neutral lipid storage disease with ichthyosis, and Gaucher disease, LB secretion is normal, and delivery of LB-derived proteins and LL-37 immunostaining persists high into the SC. In contrast, proteins loaded into nascent LBs and their delivery to the SC interstices decrease markedly in patients with HI, paralleled by reduced immunostaining for LL-37, HBD2, and KLK7 in the SC. In patients with EI, the cytoskeletal abnormality impairs the exocytosis of LB contents and thus results in decreased LL-37, HBD2, and KLK7 secretion, causing substantial entombment of these proteins within the corneocyte cytosol. Finally, in patients with NS, although abundant enzyme proteins loaded in parallel with accelerated LB production, LL-37 disappears, whereas KLK7 levels increase markedly in the SC.

CONCLUSIONS AND RELEVANCE

Together, these results suggest that diverse abnormalities in the LB secretory system account for the increased risk of secondary infections and impaired desquamation in patients with HI, EI, and NS.

Epidermal Differentiation in Barrier Maintenance and Wound Healing

Significance: The epidermal barrier prevents water loss and serves as the body's first line of defense against toxins, chemicals, and infectious microbes. Disruption of the barrier, either through congenital disorders of barrier formation or through wounds, puts the individual at risk for dehydration, hypersensitivity, infection, and prolonged inflammation. Epidermal barrier disorders affect millions of patients in the United States, causing loss of productivity and diminished quality of life for patients and their families, and represent a burden to the health-care system and society. Recent Advances: The genetic basis of many congenital barrier disorders has been identified in recent years, and great advances have been made in the molecular mechanisms of the formation and homeostasis of epidermal barrier, as well as acute and chronic wound healing. Progress in stem cell (SC) biology, particularly in induced pluripotent stem cells (iPSCs) and allogeneic mesenchymal stem cells (MSCs), has opened new doors for cell-based therapy of chronic wounds. Critical Issues: Understanding of the molecular mechanisms of barrier homeostasis in health and disease, as well as contributions of iPSCs and allogeneic MSCs to wound healing, will lead to the identification of novel targets for developing therapeutics for congenital barrier and wound healing disorders. Future Directions: Future studies should focus on better understanding of molecular mechanisms leading to disrupted homeostasis of epidermal barrier to identify potential therapeutic targets to combat its associated diseases.

Desmoglein 1 deficiency results in severe dermatitis, multiple allergies and metabolic wasting

The relative contribution of immunological dysregulation and impaired epithelial barrier function to allergic diseases is still a matter of debate. Here we describe a new syndrome featuring severe dermatitis, multiple allergies and metabolic wasting (SAM syndrome) caused by homozygous mutations in DSG1. DSG1 encodes desmoglein 1, a major constituent of desmosomes, which connect the cell surface to the keratin cytoskeleton and have a crucial role in maintaining epidermal integrity and barrier function. Mutations causing SAM syndrome resulted in lack of membrane expression of DSG1, leading to loss of cell-cell adhesion. In addition, DSG1 deficiency was associated with increased expression of a number of genes encoding allergy-related cytokines. Our deciphering of the pathogenesis of SAM syndrome substantiates the notion that allergy may result from a primary structural epidermal defect.

Aberrant distribution patterns of corneodesmosomal components of tape-stripped corneocytes in atopic dermatitis and related skin conditions (ichthyosis vulgaris, Netherton syndrome and peeling skin syndrome type B)

BACKGROUND

Atopic dermatitis (AD), Netherton syndrome (NS) and peeling skin syndrome type B (PSS) may show some clinical phenotypic overlap. Corneodesmosomes are crucial for maintaining stratum corneum integrity and the components' localization can be visualized by immunostaining tape-stripped corneocytes. In normal skin, they are detected at the cell periphery.

OBJECTIVE

To determine whether AD, NS, PSS and ichthyosis vulgaris (IV) have differences in the corneodesmosomal components' distribution and corneocytes surface areas.

METHODS

Corneocytes were tape-stripped from a control group (n=12) and a disease group (37 AD cases, 3 IV cases, 4 NS cases, and 3 PSS cases), and analyzed with immunofluorescent microscopy. The distribution patterns of corneodesmosomal components: desmoglein 1, corneodesmosin, and desmocollin 1 were classified into four types: peripheral, sparse diffuse, dense diffuse and partial diffuse. Corneocyte surface areas were also measured.

RESULTS

The corneodesmosome staining patterns were abnormal in the disease group. Other than in the 3 PSS cases, all three components showed similar patterns in each category. In lesional AD skin, the dense diffuse pattern was prominent. A high rate of the partial diffuse pattern, loss of linear cell-cell contacts, and irregular stripping manners were unique to NS. Only in PSS was corneodesmosin staining virtually absent. The corneocyte surface areas correlated significantly with the rate of combined sparse and dense diffuse patterns of desmoglein 1.

CONCLUSION

This method may be used to assess abnormally differentiated corneocytes in AD and other diseases tested. In PSS samples, tape stripping analysis may serve as a non-invasive diagnostic test.

Abnormal epidermal barrier in the pathogenesis of atopic dermatitis

Despite the acknowledged contributions of a defective epidermal permeability barrier, dryness of the skin, and the propensity to develop secondary infections to the etiology and pathophysiology of atopic dermatitis (AD), these epidermal changes have, until recently, been assumed to reflect downstream consequences that are secondary phenomena of the primary immunologic abnormality--the historical "inside-outside" view that AD is basically an intrinsic inflammatory disease. In this review, we focused on the role of the epidermal barrier function in the pathophysiology of AD. Specifically, we presented data in support of a barrier-initiated pathogenesis of AD, ie, the "outside-inside" concept. First, we reviewed the evidence on the existence of inherited barrier abnormalities in AD. Reported studies on the possible association of mutations in the filaggrin gene (FLG) and data on human tissue kallikreins (KLKs) and AD have been addressed. We then dealt with the question of the causal link between impaired epidermal barrier and inflammation. Finally, the association between innate immune defense system and the increased avidity of Staphylococcus aureus for atopic skin was examined. Despite very convincing evidence to support the barrier-initiated pathogenesis of AD, the view that AD reflects the downstream consequences of a primary immunologic abnormality cannot be dismissed out of hand. Almost every line of evidence in support of the role of the epidermal barrier as the "driver" of the disease activity can be challenged and at least partially contradicted by opposing evidence. Until more data are available and until all the dust settles around this issue, we should take advantage of what we already know and use our knowledge for practical purposes. Deployment of specific strategies to restore the barrier function in AD means the use of moisturizers as first-line therapy.

Netherton syndrome in one Chinese adult with a novel mutation in the SPINK5 gene and immunohistochemical studies of LEKTI

BACKGROUND

Netherton syndrome (NS) is a severe autosomal recessive ichthyosis. It is characterized by congenital ichthyosiform erythroderma, trichorrhexis invaginata, ichthyosis linearis circumflexa, atopic diathesis, and frequent bacterial infections. The disease is caused by mutations in the SPINK5 (serine protease inhibitor Kazal-type 5) gene, a new type of serine protease inhibitor involved in the regulation of skin barrier formation and immunity. We report one Chinese adult with NS. The patient had typical manifestation of NS except for trichorrhexis invaginata with an atopic diathesis and recurrent staphylococcal infections since birth.

AIMS

To evaluate the gene mutation and of its product activity of SPINK5 gene in confirmation of the diagnosis of one Chinese adult with NS.

MATERIALS AND METHODS

To screen mutations in the SPINK5 gene, 33 exons and flanking intron boundaries of SPINK5 were amplified with polymerase chain reaction (PCR) and used for direct sequencing. In addition, immunohistochemical staining of LEKTI (lymphoepithelial Kazal-type-related inhibitor) with specific antibody was used to confirm the diagnosis of NS. The results were compared with that of healthy individuals (twenty-five blood samples).

RESULTS

A G318A mutation was found at exon 5 of patient's SPINK5 gene which is a novel missense mutation. The PCR amplification products with mutation-specific primer were obtained only from the DNA of the patients and their mother, but not from their father and 25 healthy individuals. Immunohistochemical studies indicated there was no LEKTI expression in NS patient's skin and there was a strong LEKTI expression in the normal human skin.

CONCLUSION

In this report, we describe heterozygous mutation in the SPINK5 gene and expression of LEKTI in one Chinese with NS. The results indicate that defective expression of LEKTI in the epidermis and mutations of SPINK5 gene are reliable for diagnostic feature of NS with atypical clinical symptoms.

Therapeutic implications of a barrier-based pathogenesis of atopic dermatitis

Excessive Th2 cell signaling and IgE production play key roles in the pathogenesis of atopic dermatitis (AD). Yet, recent information suggests that the inflammation in AD instead is initiated by inherited insults to the barrier, including a strong association between mutations in FILAGGRIN and SPINK5 in Netherton syndrome, the latter of which provides an important clue that AD is provoked by excess serine protease activity. But acquired stressors to the barrier may also be required to initiate inflammation in AD, and in addition, microbial colonization by Staphylococcus aureus both amplifies inflammation, but also further stresses the barrier in AD. Therapeutic implications of these insights are as follows: While current therapy has been largely directed toward ameliorating Th2-mediated inflammation and/or pruritus, these therapies are fraught with short-term and potential long-term risks. In contrast, "barrier repair" therapy, with a ceramide-dominant triple-lipid mixture of stratum corneum lipids, is more logical, of proven efficacy, and it provides a far-improved safety profile.

Clinical expression and new SPINK5 splicing defects in Netherton syndrome: unmasking a frequent founder synonymous mutation and unconventional intronic mutations

Netherton syndrome (NS) is a severe skin disease caused by loss-of-function mutations in SPINK5 (serine protease inhibitor Kazal-type 5) encoding the serine protease inhibitor LEKTI (lympho-epithelial Kazal type-related inhibitor). Here, we disclose new SPINK5 defects in 12 patients, who presented a clinical triad suggestive of NS with variations in inter- and intra-familial disease expression. We identified a new and frequent synonymous mutation c.891C>T (p.Cys297Cys) in exon 11 of the 12 NS patients. This mutation disrupts an exonic splicing enhancer sequence and causes out-of-frame skipping of exon 11. Haplotype analysis indicates that this mutation is a founder mutation in Greece. Two other new deep intronic mutations, c.283-12T>A in intron 4 and c.1820+53G>A in intron 19, induced partial intronic sequence retention. A new nonsense c.2557C>T (p.Arg853X) mutation was also identified. All mutations led to a premature termination codon resulting in no detectable LEKTI on skin sections. Two patients with deep intronic mutations showed residual LEKTI fragments in cultured keratinocytes. These fragments retained some functional activity, and could therefore, together with other determinants, contribute to modulate the disease phenotype. This new founder mutation, the most frequent mutation described in European populations so far, and these unusual intronic mutations, widen the clinical and molecular spectrum of NS and offer new diagnostic perspectives for NS patients.

[A lethal variant of Netherton syndrome in a large inbred family]

Netherton syndrome is a rare autosomal recessive disorder characterized by the triad of ichthyosiform erythrodermia, typical hair dysplasia, and severe atopic features. The broad range of variable expression of this disease is well described and 20% of complications occur during the neonatal period such as hypernatremic dehydration, electrolyte imbalances, recurrent or severe infections, and failure to thrive. Mutation of the SPINK5 gene has been identified as disease-causing in Netherton syndrome, but the pathophysiology still remains unclear. Almost all SPINK5 mutations result in the absence of the serine-protease inhibitor LEKTI protein in both keratinocytes and lymphocytes. In this study, we report on a severe form of Netherton syndrome observed in three patients within a large inbred Rom family. All of them died in the first months of life despite early treatment. They were found to be homozygous for the c.1431-12G>A SPINK5 gene mutation, which has not been associated with a lethal form of the disease thus far. This family illustrates the extreme phenotype of Netherton disease of neonatal onset. Molecular diagnosis allowed further genetic counseling and prenatal testing during other pregnancies.

Revised nomenclature and classification of inherited ichthyoses: results of the First Ichthyosis Consensus Conference in Sorèze 2009

BACKGROUND

Inherited ichthyoses belong to a large, clinically and etiologically heterogeneous group of mendelian disorders of cornification, typically involving the entire integument. Over the recent years, much progress has been made defining their molecular causes. However, there is no internationally accepted classification and terminology.

OBJECTIVE

We sought to establish a consensus for the nomenclature and classification of inherited ichthyoses.

METHODS

The classification project started at the First World Conference on Ichthyosis in 2007. A large international network of expert clinicians, skin pathologists, and geneticists entertained an interactive dialogue over 2 years, eventually leading to the First Ichthyosis Consensus Conference held in Sorèze, France, on January 23 and 24, 2009, where subcommittees on different issues proposed terminology that was debated until consensus was reached.

RESULTS

It was agreed that currently the nosology should remain clinically based. "Syndromic" versus "nonsyndromic" forms provide a useful major subdivision. Several clinical terms and controversial disease names have been redefined: eg, the group caused by keratin mutations is referred to by the umbrella term, "keratinopathic ichthyosis"-under which are included epidermolytic ichthyosis, superficial epidermolytic ichthyosis, and ichthyosis Curth-Macklin. "Autosomal recessive congenital ichthyosis" is proposed as an umbrella term for the harlequin ichthyosis, lamellar ichthyosis, and the congenital ichthyosiform erythroderma group.

LIMITATIONS

As more becomes known about these diseases in the future, modifications will be needed.

CONCLUSION

We have achieved an international consensus for the classification of inherited ichthyosis that should be useful for all clinicians and can serve as reference point for future research.

Therapeutic Implications of a Barrier-based Pathogenesis of Atopic Dermatitis

In this review, I first provide relevant background information about normal epidermal barrier structure and function. I then update recent information about how inherited defects in either filaggrin and/or in the serine protease inhibitor, lymphoepithelial Kazal-type inhibitor 1, converge to stimulate the development of atopic dermatitis (AD). Next I explain the multiple mechanisms whereby a primary barrier abnormality in AD can lead to inflammation. Furthermore, I explore how certain acquired stressors, such as a reduced external humidity, high pH soaps/surfactants, psychological stress, as well as secondary Staphylococcus aureus infections initiate or further aggravate AD. Finally, and most importantly, I compare various therapeutic paradigms for AD, highlighting the risks and benefits of glucocorticoids and immunomodulators vs. corrective, lipid replacement therapy.

Elastase 2 is expressed in human and mouse epidermis and impairs skin barrier function in Netherton syndrome through filaggrin and lipid misprocessing

The human epidermis serves 2 crucial barrier functions: it protects against water loss and prevents penetration of infectious agents and allergens. The physiology of the epidermis is maintained by a balance of protease and antiprotease activities, as illustrated by the rare genetic skin disease Netherton syndrome (NS), in which impaired inhibition of serine proteases causes severe skin erythema and scaling. Here, utilizing mass spectrometry, we have identified elastase 2 (ELA2), which we believe to be a new epidermal protease that is specifically expressed in the most differentiated layer of living human and mouse epidermis. ELA2 localized to keratohyalin granules, where it was found to directly participate in (pro-)filaggrin processing. Consistent with the observation that ELA2 was hyperactive in skin from NS patients, transgenic mice overexpressing ELA2 in the granular layer of the epidermis displayed abnormal (pro-)filaggrin processing and impaired lipid lamellae structure, which are both observed in NS patients. These anomalies led to dehydration, implicating ELA2 in the skin barrier defect seen in NS patients. Thus, our work identifies ELA2 as a major new epidermal protease involved in essential pathways for skin barrier function. These results highlight the importance of the control of epidermal protease activity in skin homeostasis and designate ELA2 as a major protease driving the pathogenesis of NS.

COMUS: Clinician-Oriented locus-specific MUtation detection and deposition System

Background

A disease-causing mutation refers to a heritable genetic change that is associated with a specific phenotype (disease). The detection of a mutation from a patient's sample is critical for the diagnosis, treatment, and prognosis of the disease. There are numerous databases and applications with which to archive mutation data. However, none of them have been implemented with any automated bioinformatics tools for mutation detection and analysis starting from raw data materials from patients. We present a Locus Specific mutation DB (LSDB) construction system that supports both mutation detection and deposition in one package.

Results

COMUS (Clinician-Oriented locus specific MUtation detection and deposition System) is a mutation detection and deposition system for developing specific LSDBs. COMUS contains 1) a DNA sequence mutation analysis method for clinicians' mutation data identification and deposition and 2) a curation system for variation detection from clinicians' input data. To embody the COMUS system and to validate its clinical utility, we have chosen the disease hemophilia as a test database. A set of data files from bench experiments and clinical information from hemophilia patients were tested on the LSDB, KoHemGene http://www.kohemgene.org, which has proven to be a clinician-friendly interface for mutation detection and deposition.

Conclusion

COMUS is a bioinformatics system for detecting and depositing new mutations from patient DNA with a clinician-friendly interface. LSDBs made using COMUS will promote the clinical utility of LSDBs. COMUS is available at http://www.comus.info.

Ichthyosis: clinical manifestations and practical treatment options

Ichthyoses constitute a large group of cornification disorders that affect the entire integument. The skin is characterized by visible scaling and in many cases by inflammation, for example, in bullous/keratinopathic ichthyosis or Netherton syndrome. From the viewpoint of classification it is useful to distinguish non-syndromic from syndromic types of ichthyosis. Ichthyosis vulgaris and recessive X-linked ichthyosis are common disorders - often of delayed onset, in contrast to congenital ichthyoses, which belong to the group of rare diseases and present at birth with either the features of collodion membrane or congenital ichthyosiform erythroderma. The diagnostic steps are based on clinical data, analyses such as the steroid sulfatase activity test, skin biopsies, and genetic results. However, the dramatic increase in knowledge about the pathophysiology of these conditions has not led to a curative therapy so far. The therapeutic management is multidisciplinary and involves ichthyosis patient organizations in many countries. The mainstay of treatment remains with moisturizing creams containing, for example, urea, lactic acid and other humectants and keratolytics, regular bathing, and mechanical scale removal. Patients with lamellar ichthyosis or ichthyosiform erythroderma in particular profit from oral therapy with retinoids or retinoic acid metabolism-blocking agents.

Ichthyoses--Part 2: Congenital ichthyoses

Congenital ichthyoses are a group of genetic disorders with defective cornification, clinically characterized by scaling of the skin. Additionally, distinctive cutaneous inflammation can often be observed. For most of the patients these diseases lead to a significant restriction in quality of life. The diagnostic hallmarks are discussed. The diagnostic criteria include clinical and histological findings, often enhanced or confirmed by specialized tests. Because many of the congenital ichthyoses are extremely rare, their accurate diagnosis is often carried out in specialized centers. After discussing the vulgar ichthyoses as well as the diagnostic and therapeutic options in part one, in this second part we review congenital ichthyoses both with and without associated symptoms, focusing on the common genetic changes and their clinical phenotype. Specific therapies are still not available for most of these disorders. The use of different topical agents (e. g. urea, retinoids and salicylic acid) and baths followed by mechanical keratolysis (sometimes in combination with systemic retinoids) reduce skin symptoms. Patients with uncommon congenital ichthyoses often benefit from interdisciplinary management which involves specialized dermatological centers.

Ichthyoses - Part 1: Differential diagnosis of vulgar ichthyoses and therapeutic options

Ichthyoses are a group of genetic disorders with defective cornification, clinically characterized by scaling of the skin. Additionally, distinctive cutaneous inflammation can often be observed. For most of the patients these diseases lead to a significant restriction in quality of life. The diagnostic criteria include clinical and histological findings, often confirmed by specialized tests. Because many of the ichthyoses are extremely rare, their accurate diagnosis is often carried out in specialized centers. We summarize isolated vulgar and congenital ichthyoses both with and without associated symptoms and focus on the common genetic changes and their clinical phenotype. Specific therapies are still not available for most of these genetic disorders. The use of different topical agents (e. g. urea, retinoids and salicylic acid) and baths followed by mechanical keratolysis (sometimes in combination with systemic retinoids) reduce symptoms. Patients with uncommon congenital ichthyoses often benefit from interdisciplinary management which involves specialized dermatological centers. In this first part of the paper the vulgar ichthyoses as well as the diagnostic and therapeutic options are discussed. The second part focuses on the congenital ichthyoses and their differential diagnosis.