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.

Management of congenital ichthyoses: European guidelines of care, part one.

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. They summarize evidence and expert-based recommendations and are intended to help clinicians with the management of these rare and often complex diseases. These guidelines comprise two sections. This is part one, covering topical therapies, systemic therapies, psychosocial management, communicating the diagnosis and genetic counselling.

Sixteen novel mutations in PNPLA1 in patients with autosomal recessive congenital ichthyosis reveal the importance of an extended patatin domain in PNPLA1 that is essential for proper human skin barrier function.

BACKGROUND: Autosomal recessive congenital ichthyosis (ARCI) is a genetically heterogeneous group of rare Mendelian skin disorders characterized by cornification and differentiation defects of keratinocytes. Mutations in nine genes including PNPLA1 are known to cause nonsyndromic forms of ARCI. To date, only 10 distinct pathogenic mutations in PNPLA1 have been reported. OBJECTIVES: To identify new causative PNPLA1 mutations. METHODS: We screened genetically unresolved cases, including our ARCI collection, comprising more than 700 families. Screening for mutations was performed either by direct Sanger sequencing or in combination with a multigene panel, followed by sequence and mutation analysis. RESULTS: Here we report on 16 novel mutations present in patients from 17 families. While all previously reported mutations and most of our novel mutations are located within the core patatin domain, we report five novel PNPLA1 mutations that are downstream of this domain. Thus, as recently described for PNPLA2, we hypothesize that a region larger than the core domain is required for full enzymatic activity of PNPLA1 in human skin barrier formation. CONCLUSIONS: We estimate the frequency of PNPLA1 mutations among patients with ARCI to be around 3%. Most of our patients were born as collodion babies and showed a relatively mild ichthyosis phenotype. In four unrelated patients we observed a cyclic scaling course, which seems to be a potential phenotypic variation in a small percentage of patients with PNPLA1 mutations. The variability of the clinical manifestations and the lack of typical clinical features are specific for patients with PNPLA1 mutations, and emphasize the importance of DNA sequencing for differential diagnosis of ARCIs.

Moisturizing treatment of patients with atopic dermatitis and ichthyosis vulgaris improves dry skin, but has a modest effect on gene expression regardless of FLG genotype.

BACKGROUND: Loss-of-function mutations in FLG (encoding filaggrin) are a predisposing factor for atopic dermatitis (AD) and cause ichthyosis vulgaris (IV). Patients with AD and IV display impaired skin barrier and dry skin, and altered epidermal expression of genes in pro-inflammatory and lipid metabolic pathways are often evident. OBJECTIVES: To evaluate the effect of three different moisturizers on skin barrier function and epidermal gene expression in patients with AD/IV in relation to FLG mutation status. METHODS: Patients (n = 43) were classified according to their FLG status: AD with FLG+/+ (n = 14), AD with FLG+/- (n = 14), and AD/IV with FLG-/- (n = 15). Dryness score and transepidermal water loss (TEWL) were monitored on volar forearms, and punch biopsies were taken for analysis of gene expression. Measurements were repeated after 4 weeks of treatment with either of two moisturizers on each forearm. RESULTS: Treatment with any of the three moisturizers significantly reduced dryness score and TEWL in the group as a whole. FLG-/- patients displayed the largest reduction in dryness score. Only minute changes occurred in the mRNA expression of 15 selected epidermal genes. CONCLUSIONS: Moisturizing treatment improves dry skin and certain aspects of abnormal skin barrier function, especially in patients with AD/IV and dual FLG mutations, but does not normalize the epidermal gene expression profile.

A Scandinavian case of skin fragility, alopecia and cardiomyopathy caused by DSP mutations.

Congenital skin fragility is a heterogeneous disorder with epidermolysis bullosa and various skin infections as the leading causes. However, even rare diseases must be considered in the differential diagnosis of neonatal skin blistering, including some genetic syndromes with extracutaneous involvement. One such syndrome is ectodermal dysplasia due to deficiency of desmoplakin, a desmosomal protein essential for cellular cohesion in both epithelia and cardiac tissues. Desmoplakin is encoded by the DSP gene, which is localized on chromosome 6p24. Both dominant and recessive mutations in this gene have been reported to cause skin fragility and keratinization defects. We report a child born with a fragile epidermis, alopecia, thick nails, and focal hyperkeratoses on the digits and knees. She was found to have a deficiency of desmoplakin caused by compound heterozygous DSP mutations. She has gradually developed signs of a left ventricular cardiomyopathy.

Oral liarozole in the treatment of patients with moderate/severe lamellar ichthyosis: results of a randomized, double-blind, multinational, placebo-controlled phase II/III trial.

BACKGROUND: Oral liarozole, a retinoic acid metabolism-blocking agent, may be an alternative to systemic retinoid therapy in patients with lamellar ichthyosis. OBJECTIVE: To demonstrate the efficacy and safety of once-daily oral liarozole in the treatment of moderate/severe lamellar ichthyosis. METHODS: This was a double-blind, multinational, parallel phase II/III trial (NCT00282724). Patients aged ≥ 14 years with moderate/severe lamellar ichthyosis [Investigator's Global Assessment (IGA) score ≥ 3] were randomized 3 : 3 : 1 to receive oral liarozole (75 or 150 mg) or placebo once daily for 12 weeks. Assessments included: IGA; a five-point scale for erythema, scaling and pruritus severity; Short Form-36 health survey; Dermatology Life Quality Index (DLQI); and safety parameters. The primary efficacy variable was response rate at week 12 (responder: ≥ 2-point decrease in IGA from baseline). RESULTS: Sixty-four patients were enrolled. At week 12, 11/27 (41%; liarozole 75 mg), 14/28 (50%; liarozole 150 mg) and one out of nine (11%; placebo) patients were responders; the difference between groups (liarozole 150 mg vs. placebo) was not significant (P = 0.056). Mean IGA and scaling scores decreased from baseline in both liarozole groups at weeks 8 and 12 vs. placebo; erythema and pruritus scores were similar between treatment groups. Improvement in DLQI score was observed in both liarozole groups. Treatment with liarozole for 12 weeks was well tolerated. CONCLUSIONS: The primary efficacy variable did not reach statistical significance, possibly owing to the small sample size following premature termination. However, once-daily oral liarozole, 75 and 150 mg, improved scaling and DLQI and was well tolerated in patients with moderate/severe lamellar ichthyosis.

X-linked recessive ichthyosis: an impaired barrier function evokes limited gene responses before and after moisturizing treatments.

BACKGROUND: X-linked recessive ichthyosis (XLRI) is due to deletions or inactivating mutations in the steroid sulfatase (STS) gene. This results in an accumulation of cholesterol sulphate affecting the packing of intercorneocyte lipids. XLRI is characterized by dry, scaly skin and increased skin barrier permeability; patients are often dependent on daily use of moisturizers. OBJECTIVES: To examine the biophysical and molecular changes in the skin of patients with XLRI compared with healthy volunteers, and to analyse the effects of moisturizers on the patients' barrier function. METHODS: Patients with XLRI (n=14) and healthy controls (n=14) were included in the study. Skin dryness score, transepidermal water loss (TEWL) and skin surface pH were monitored at baseline, and punch biopsies were obtained for mRNA expression profiles determined by oligonucleotide arrays. Measurements were repeated in the patients with XLRI after a 4-week treatment with three different moisturizers on the volar forearms. RESULTS: Patients with XLRI showed, compared with healthy controls, increased dryness and TEWL, equal skin pH and altered expression of 27 genes. There were no signs of activation of inflammation or repair pathways. Five selected genes were significantly altered also on quantitative polymerase chain reaction analysis. Treatment with the moisturizers showed similar effects: they improved skin dryness but had no effect on TEWL, pH or expression of selected genes. CONCLUSIONS: Despite a dysfunctional skin barrier, the limited number of genes altered in XLRI skin suggests that no inflammatory or repair mechanisms are triggered. Treatment with moisturizers does not have any major impact on the skin barrier properties of patients with XLRI.

Immortalized keratinocytes derived from patients with epidermolytic ichthyosis reproduce the disease phenotype: a useful in vitro model for testing new treatments.

BACKGROUND: Epidermolytic ichthyosis (EI) is a skin fragility disorder caused by mutations in genes encoding suprabasal keratins 1 and 10. While the aetiology of EI is known, model systems are needed for pathophysiological studies and development of novel therapies. OBJECTIVES: To generate immortalized keratinocyte lines from patients with EI for studies of EI cell pathology and the effects of chemical chaperones as putative therapies. METHODS: We derived keratinocytes from three patients with EI and one healthy control and established immortalized keratinocytes using human papillomavirus 16-E6/E7. Growth and differentiation characteristics, ability to regenerate organotypic epidermis, keratin expression, formation of cytoskeletal aggregates, and responses to heat shock and chemical chaperones were assessed. RESULTS: The cell lines EH11 (K1_p.Val176_Lys197del), EH21 (K10_p.156Arg>Gly), EH31 (K10_p.Leu161_Asp162del) and NKc21 (wild-type) currently exceed 160 population doublings and differentiate when exposed to calcium. At resting state, keratin aggregates were detected in 9% of calcium-differentiated EH31 cells, but not in any other cell line. Heat stress further increased this proportion to 30% and also induced aggregates in 3% of EH11 cultures. Treatment with trimethylamine N-oxide and 4-phenylbutyrate (4-PBA) reduced the fraction of aggregate-containing cells and affected the mRNA expression of keratins 1 and 10 while 4-PBA also modified heat shock protein 70 (HSP70) expression. Furthermore, in situ proximity ligation assay suggested a colocalization between HSP70 and keratins 1 and 10. Reconstituted epidermis from EI cells cornified but EH21 and EH31 cells produced suprabasal cytolysis, closely resembling the in vivo phenotype. CONCLUSIONS: These immortalized cell lines represent a useful model for studying EI biology and novel therapies.

Botulinum toxin in the treatment of sweat-worsened foot problems in patients with epidermolysis bullosa simplex and pachyonychia congenita.

BACKGROUND: Painful foot blistering is a common problem in patients with epidermolysis bullosa simplex (EBS) and pachyonychia congenita (PC). Hyperhidrosis, a condition which can be effectively blocked by plantar injections of botulinum toxin (Btx), often exacerbates the blistering. OBJECTIVES: A retrospective evaluation of the effects of Btx injections in 14 patients with EBS and PC with foot blisters and painful callosities. METHODS: After informed consent, patients with EBS (n = 6) and PC (n = 8), aged 7-66 years, who had received Btx therapy at our centre since 2003, were included. The treatment consisted of multiple plantar injections of Btx A or Btx B after prior regional or general anaesthesia. Patients were interviewed about the treatment effect and were asked to score the improvement from 0 to 5, where 5 is 'excellent'. One patient with PC with painful callosities was studied by magnetic resonance (MR) spectroscopic microimaging before and after Btx injections to disclose any underlying blisters. RESULTS: In total, 76 treatments were evaluated (one to 19 sessions per patient). Thirteen patients (93%) reported reduced plantar blistering and pain; the improvement score was ≥ 4 in four of six patients with EBS and six of eight patients with PC. The mean effect duration was 3 months. No adverse events, apart from mild anticholinergic side-effects in two patients, were noted. MR spectroscopic microimaging showed disappearance of intraepidermal blistering after Btx therapy. CONCLUSIONS: Plantar injection of Btx is an efficient, long-lasting and safe treatment of painful blistering and callosities in EBS and PC that can be given repeatedly without loss of efficacy.

Epidermolysis bullosa simplex due to KRT5 mutations: mutation-related differences in cellular fragility and the protective effects of trimethylamine N-oxide in cultured primary keratinocytes.

BACKGROUND: Epidermolysis bullosa simplex (EBS) is a mechanobullous skin fragility disease characterized by cytolysis of basal keratinocytes and intraepidermal blistering often caused by mutations in keratin genes (KRT5 or KRT14). No remedies exist for these disorders presenting a need for development of novel therapies. OBJECTIVES: To identify new genotype-phenotype relationships in vivo and in cultured primary EBS keratinocytes in vitro, and to study the cytoskeletal stabilizing effects of trimethylamine N-oxide (TMAO) in heat-stressed EBS cells. METHODS: Genomic DNA and cDNA samples from three Swedish patients with EBS were analysed for keratin mutations. Primary EBS keratinocyte cultures were established, heat stressed with and without added TMAO, followed by evaluation of cellular fragility. RESULTS: In addition to the previously reported KRT5 mutation (V186L) in one patient, two patients were found to have a novel I183M and recurrent E475G replacements in KRT5. Cultured EBS keratinocytes did not exhibit keratin aggregates or cell loss, except in the patient with the p.I183M mutation who showed 3% aggregates and 2% cell loss. Upon transient heat stress the number of aggregate-containing cells increased to 21%, 27% and 13%, respectively, in the p.I183M, p.E475G and p.V186L mutant cells. Interestingly, pretreatment with TMAO prior to heat stress, dose dependently reduced the number of aggregate-containing cells and cell loss. CONCLUSION: These results revealed a genotype-phenotype correlation in EBS keratinocytes upon heat stress and suggest protein stabilization as a new therapeutic strategy.

Topical treatment with CYP26 inhibitor talarozole (R115866) dose dependently alters the expression of retinoid-regulated genes in normal human epidermis.

BACKGROUND: An alternative approach to retinoid therapy is to inhibit the cytochrome P450 (CYP)-mediated catabolism of endogenous all-trans retinoic acid in the skin by applying retinoic acid metabolism blocking agents such as talarozole (R115866). OBJECTIVES: To study the effects of topical talarozole on retinoid biomarkers in normal skin in a randomized phase I trial. METHODS: Gels containing talarozole (0.35% or 0.07%) and vehicle were applied once daily for 9 days on either buttock of 16 healthy volunteers. Epidermal shave biopsies (for mRNA analysis) and punch biopsies (for histology and immunofluorescence analysis) were collected from the treatment areas. Genes encoding the following were studied by quantitative real-time polymerase chain reaction: cellular retinoic acid binding protein 2 (CRABP2), cytokeratins (KRT2 and KRT4), CYP26A1, CYP26B1, CYP26C1 and CYP2S1, two enzymes in the retinol metabolism (retinal dehydrogenase-2 and retinol acyltransferase) and two proinflammatory cytokines [interleukin (IL)-1alpha and tumour necrosis factor-alpha]. RESULTS: Talarozole treatment increased the mRNA expression of CRABP2, KRT4, CYP26A1 and CYP26B1 dose dependently, and decreased the expression of KRT2 and IL-1alpha compared with vehicle-treated skin. No mRNA change in retinol-metabolizing enzymes was obtained. There was no induction of epidermal thickness or overt skin inflammation in talarozole-treated skin. Immunofluorescence analysis confirmed an upregulation of KRT4 protein, but no upregulation of CYP26A1 and CYP26B1 expression was detected. CONCLUSIONS: Talarozole influences the biomarker pattern consistently with increased retinoic acid stimulation. The low irritancy of talarozole at the two examined dosages is a possible advantage over topical retinoids.

Congenital ichthyosis: mutations in ichthyin are associated with specific structural abnormalities in the granular layer of epidermis.

BACKGROUND: Autosomal recessive congenital ichthyosis (ARCI) is a heterogeneous group of skin disorders. Several mutant genes have been identified in ARCI, but the association between genotype and phenotype is poorly understood. METHODS: To investigate genotype-phenotype correlations in ARCI, we selected 27 patients from 18 families with specific ultrastructural features of the epidermis. The characteristic findings using electron microscopy (EM) were abnormal lamellar bodies and elongated membranes in the stratum granulosum, classified as ARCI EM type III. DNA samples from a subset of affected individuals were screened for homozygous genomic regions, and a candidate gene region was identified on chromosome 5q33. The region coincides with the ichthyin gene, previously reported as mutated in ARCI. RESULTS: Mutation screening of ichthyin revealed missense or splice-site mutations in affected members from 16 of 18 (89%) families with characteristics of ARCI EM type III. In a control group of 18 patients with ARCI without EM findings consistent with type III, we identified one patient homozygous for a missense mutation in ichthyin. DISCUSSION: Our findings indicate a strong association between ultrastructural abnormalities in the granular layer of epidermis and ichthyin mutations. The results also suggest that EM provides a tool for specific diagnosis in a genetically homogenous subgroup of patients with ARCI.

A founder mutation for ichthyosis prematurity syndrome restricted to 76 kb by haplotype association.

Autosomal recessive congenital ichthyosis (ARCI) is a group of keratinisation disorders that includes the ichthyosis prematurity syndrome (IPS). IPS is rare and almost exclusively present in a restricted region in the middle of Norway and Sweden, which indicates a founder effect for the disorder. We recently reported linkage of IPS to chromosome 9q34, and we present here the subsequent fine-mapping of this region with known and novel microsatellite markers as well as single nucleotide polymorphisms (SNPs). Allelic association, evaluated with Fisher's exact test and P (excess), was used to refine the IPS haplotype to approximately 1.6 Mb. On the basis of the average length of the haplotype in IPS patients, we calculated the age of a founder mutation to approximately 1,900 years. The IPS haplotype contains a core region of 76 kb consisting of four marker alleles shared by 97.7% of the chromosomes associated with IPS. This region spans four known genes, all of which are expressed in mature epidermal cells. We present the results from the analysis of these four genes and their corresponding transcripts in normal and patient-derived samples.

Treatment of pachyonychia congenita with plantar injections of botulinum toxin.

Pachyonychia congenita (PC) is a rare genodermatosis which may be associated with painful, focal hyperkeratosis on the soles. Plantar sweating at high ambient temperatures increases the blistering of the callosities. We report three patients with PC who had great problems in walking, especially during summer time. They were treated with intracutaneous plantar injections of botulinum toxin type A (Dysport, 100 U mL(-1); Ipsen, Slough, U.K.) after prior intravenous regional anaesthesia of the foot with a low tourniquet and 25 mL prilocaine (5 mg mL(-1)). Within a week all three patients experienced dryness and a remarkable relief of pain from plantar pressure sites. The effect duration was 6 weeks to 6 months. Repeated injections over a 2-year period confirmed the good results, with no side-effects or tachyphylaxis noted.

Inefficacy of topical thyroid hormone analogue TriAc in plaque psoriasis: results of a double-blind placebo-controlled trial.

BACKGROUND: Thyroid hormone receptors are expressed in human skin and are believed to be involved in the regulation of epidermal proliferation and differentiation, i.e. processes which are disturbed in psoriatic skin lesions. Ligands of the thyroid hormone receptors have so far not been tested as antipsoriatic agents. TriAc (3,3',5-triiodo-thyroacetic acid) is a well-known thyroid hormone analogue with much reduced cardiac thyrotoxic activity compared with the classical thyroid hormones. OBJECTIVES: To determine the effectiveness and side-effects of topical TriAc in patients with chronic plaque psoriasis. METHODS: Twelve patients with mild to moderate psoriasis were treated with TriAc (0.1% in hydrophilic ointment) and placebo applied twice daily to either of two (or several) bilaterally symmetrical plaques for 8 weeks. The patients and investigator were blinded as to the content of the tubes. Every 2 weeks the treated plaques were evaluated by the patient (using a balanced visual analogue scale for a right-left comparison) and by the investigator (using a psoriasis severity index and a global assessment of each plaque). RESULTS: After 8 weeks of treatment, more than 33% improvement of the psoriasis index occurred in 10 of 12 TriAc-treated and nine of 12 placebo-treated plaques. There were no statistically significant differences between the treatments in terms of reduction of the scores for erythema, scaling, induration or pruritus during the study. Half of the patients considered TriAc superior to placebo, whereas three of 12 were of the opposite opinion (P > 0.05). The global assessment showed marked improvement or remission in six TriAc-treated and five placebo-treated cases (P > 0.05 for difference). No adverse effects were noted. CONCLUSIONS: TriAc in the dosage and formulation studied was safe but no more effective than placebo in treating plaque psoriasis. However, newer thyroid hormone analogues (agonists or antagonists) might be more active and should be further explored in this context.