Investigation of gamma secretase gene complex mutations in German population with Hidradenitis suppurativa designate a complex polygenic heritage.

BACKGROUND: Hidradenitis suppurativa (HS) is a chronic inflammatory disease affecting apocrine gland-bearing skin in the axilla, groin and under the breasts. Mutations of the gamma secretase gene complex, which is essential in the activation of Notch signalling pathways, were shown in some families with HS and in a few sporadic cases. Although an imbalance in Notch signalling is implicated in the pathogenesis, the exact mechanism of HS development is yet unknown. OBJECTIVES: We aim to investigate the genetic basis of HS by determining the presence of mutations of gamma secretase gene complex in a cohort of HS patients and by searching for a disease-causing pathogenic variant in a multi-generational HS family using parametric linkage analysis. METHODS: Thirty-eight patients clinically diagnosed with HS were included in this study. All exons and exon-intron boundaries of the genes encoding gamma secretase complex consisting of six genes: APH1A, APH1B, PSENEN, NCSTN, PSEN1 and PSEN2 were sequenced by Sanger technique. Genetic mapping with parametric linkage analysis for the patients in the family was performed with eight affected and four healthy individuals. The logarithm of odds was calculated. RESULTS: In a sporadic patient with early-onset, severe lesions in axilla and groin, a novel single-nucleotide deletion causing frameshift in exon 1 of the NCSTN gene was identified ((NM_015331.3): c.38delG, p.(Gly13Glufs*15)). The LOD score of 1.5 was never exceeded in any region of the genome, pointing towards intricate multi-genic inheritance pattern within the affected family. CONCLUSIONS: The gamma secretase gene complex mutations were rare in our cohort (3.2%). Besides, our analysis indicates a possible complex multi-genic inheritance in a seemingly autosomal dominantly inherited large HS family. Genetics of both familial and sporadic HS may be complicated in most cases, and the role of other potential genes such as autoinflammatory and modifier genes as well as environmental factors may influence the pathogenesis.

[Palmoplantar dermatoses in children]. / Dermatosen an Händen und Füßen bei Kindern.

Dermatoses of the hands and feet cover a wide range of skin diseases that can occur in children and adolescents and are a frequent question in dermatological practice. Our synopsis of the most important differential diagnoses and their treatment is intended to provide better orientation for daily practice. A precise and detailed history is essential to establish a diagnosis, followed by clinical examination and specific examination methods. Cutaneous infection should always be excluded, as they occur very frequently. Impetigo, punctate keratolysis, blistering distal dactylitis, tinea manuum and pedum, hand-foot-mouth disease, herpes simplex digitalis and verrucae vulgaris as well as scabies are often found in the palmoplantar area and typically affect children and adolescents. In case of allergic contact dermatitis and dyshidrotic eczema, atopic diathesis in the medical history is of importance. However, we must not miss rare causes. Palmoplantar keratoses, for example, can be due to inflammatory dermatoses like pityriasis rubra pilaris (PRP) or may, as well as blistering diseases, result from hereditary disorders. Specialised centers can perform molecular genetic diagnosis and enhance patient care.

Association of pyrin mutations and autoinflammation with complex phenotype hidradenitis suppurativa: a case-control study.

BACKGROUND: Hidradenitis suppurativa (HS) is a rare, debilitating neutrophilic dermatosis characterized by chronic inflammation of hair follicles. Many inflammatory conditions may accompany HS. OBJECTIVES: To investigate the association of variants of the MEFV gene with a complex HS phenotype. METHODS: Firstly, we identified the clinical characteristics of 119 patients with HS with a complex phenotype (Hurley stage III disease and/or additional inflammatory symptoms). Then, we searched for MEFV variants among these patients. The odds ratios (ORs) for pathogenic MEFV mutations were calculated using data from these patients with HS and 191 healthy controls. RESULTS: The male/female ratio was higher, and the mean age of onset was earlier, in our complex HS group compared with patients with HS in general. Five of the patients with HS (4·2%) had a diagnosis of familial Mediterranean fever (FMF) with a standardized morbidity ratio of 45 [95% confidence interval (CI) 16·50-99·84, P < 0·001] when compared with the frequency of FMF in the general Turkish population. Of the patients with complex HS, 38% were positive for pathogenic variants of MEFV. The OR for carrying a pathogenic MEFV allele was 2·80 (95% CI 1·31-5·97, P < 0·001). CONCLUSIONS: The frequency of MEFV mutations in the group of patients with complex HS was higher than that in healthy controls, suggesting that MEFV mutations may contribute to the pathogenesis of HS. Understanding the role of autoinflammation in HS is of fundamental importance for the development of novel therapies.

Burden of itch in ichthyosis: a multicentre study in 94 patients.

BACKGROUND: From clinical experience, we know that itch is a major concern for many ichthyosis patients. Nonetheless, no previous studies specifically addressed the issue of itch in ichthyosis. OBJECTIVE: The objective of this study was to specifically address the burden of itch and all its dimensions in ichthyosis patients. METHODS: Ninety-four ichthyosis patients from four different centres were recruited to participate in this cross-sectional, questionnaire-based study. All participants completed the Leuven Itch Scale, a multidimensional self-report instrument that quantifies the frequency, duration, severity, distress, consequences and surface area of itch. RESULTS: Participants included 18 keratinopathic types, 55 autosomal recessive congenital ichthyoses, 11 X-linked recessive ichthyoses (XLRIs), 6 Netherton's ichthyoses, 1 Sjögren-Larsson type, 1 Iocrin ichthyosis and 2 unknown subtypes. Itch occurred in 93% of all patients. In patients with itch, 63% reported that it was often or always present, although most itch episodes were short in duration. Itch, in all its dimensions, was worst in patients with Netherton syndrome. Patients with XLRI had in general a lower itch profile. About half of all ichthyosis patients reported to experience flares during a change in weather, in a hot environment or in stressful situations, whereas a cold environment led to itch in only 26% of patients. The most significant consequences of itching were lesions from scratching, difficulties in falling asleep, bad mood and loss of concentration. CONCLUSIONS: Itch is a major concern in patients with ichthyosis, with significant impact on daily life. Research on future treatments should therefore take itch into consideration and itch should be evaluated in clinical studies. Among the studied subgroups, Netherton patients experienced the most severe consequences.

Non-invasive diagnosis of sweat gland dysplasia using optical coherence tomography and reflectance confocal microscopy in a family with anhidrotic ectodermal dysplasia (Christ-Siemens-Touraine syndrome).

BACKGROUND: Anhidrotic ectodermal dysplasia (AED) is an inherited syndrome, which originates mainly from genetic alteration of the ectodysplasin A (EDA) gene. It regularly affects the adnexa of the skin which results in a characteristic phenotype of the patients including hypo- or anhidrosis leading to severe disturbances in the regulation of body temperature. OBJECTIVES: To prevent the development of the symptoms in early childhood promising therapeutic approaches are currently under clinical investigation. In this context, timely diagnosis of this genetic syndrome is crucial. The purpose of our study was the investigation of modern non-invasive imaging methods such as optical coherence tomography (OCT) and reflectance confocal microscopy (RCM) in the immediate diagnosis of AED. METHODS: We examined a 3-year-old boy with the suspicion for an AED syndrome and his family members with RCM and OCT to document presence and characteristic features of sweat glands in comparison to non-affected individuals. RESULTS: The patient and the affected brother showed significantly reduced sweat glands in the imaging compared to the controls. The genetic analysis revealed a mutation of the EDA gene for hemizygosity previously associated with AED and the mother was revealed as the conductor of the genetic alteration. CONCLUSIONS: With the help of non-invasive imaging, we were able to detect sweat gland dysplasia in the affected family members without performing a biopsy which led us to the diagnosis of an AED. The application of modern dermatological imaging techniques might serve as valuable supplementary tools in the immediate, non-invasive diagnosis of genetic syndromes especially in newborns when early therapeutic approaches are planned.

[Palmoplantar dermatoses: when should genes be considered?]. / Hautveränderungen an Händen und Füßen: Wann muss man an die Gene denken?

BACKGROUND: Palmoplantar dermatoses are common. They can be both functionally debilitating and markedly stigmatize the patient because they are so visible. Dermatoses on the hands and feet often go along with palmoplantar hyperkeratosis. Such palmoplantar keratoses (PPK) can be classified into acquired (non-hereditary) and hereditary (monogenetic) PPK. OBJECTIVES: A considerable proportion of PPK develop on the grounds of gene defects. As these diseases constitute a heterogeneous group of quite uncommon single entities, the treating physician must know when to entertain the diagnosis of a hereditary PPK and which causative genes should be considered. METHODS: We summarize the common causes of acquired and hereditary PPK based on a review of the latest literature. RESULTS: The most common causes of acquired PPK are inflammatory dermatoses like psoriasis, lichen planus, or hand and feet eczema. Also irritative-toxic (arsenic poisoning, polycyclic aromatic hydrocarbons) and infectious causes of PPK (human papilloma viruses, syphilis, scabies, tuberculosis, mycoses) are not uncommon. Genetically caused PPK may occur isolated, within syndromes or as a paraneoplastic marker. The clinical/histological classification discerns diffuse, focal, or punctuate forms of PPK with and without epidermolysis. A new classification based on the causative gene defect is starting to replace the traditional clinical classification. CONCLUSIONS: Knowledge about the large, but heterogeneous group of hereditary PPK is important to adequately counsel and treat patients and their families.

[Genetic hair diseases. An update]. / Genetisch bedingte Haarerkrankungen. Ein Update.

Patients suffering from hair loss or undesirable excessive hair growth are a challenge for dermatologists because the pathogenesis of most hair diseases is not well understood and therapeutic options are limited. This particularly holds true for genetic hair disorders, in which all current treatment attempts are unsuccessful. Furthermore, these diseases also pose a diagnostic challenge due to a broad range of clinical and genetic heterogeneity. However, the enormous progress in molecular biology over the past 20 years, in particular the availability of different new techniques such as whole exome and genome sequencing, has enabled us to elucidate the genetic basis of most monogenic hair disorders, given the availability of suitable index patients and families as well as adequate technical equipment and sufficient financial resources. In this review we provide an update on clinical and genetic aspects of selected monogenic and polygenic hair diseases manifesting with hypertrichosis and hypotrichosis.

Investigation of selected cytokine genes suggests that IL2RA and the TNF/LTA locus are risk factors for severe alopecia areata.

BACKGROUND: Alopecia areata (AA) is the second most common cause of hair loss in humans, and has a genetically complex inheritance. The hypothesis that AA is autoimmune in nature is supported by previous studies. These report an association with specific HLA alleles, as well as genetic variants of other genes implicated in autoimmunity, such as various cytokine genes. However, these cannot yet be considered proven susceptibility loci, as many of these association findings were derived from small patient samples. OBJECTIVES: To investigate the association between AA and selected cytokine genes using a sample of 768 patients with AA and 658 controls of Central European origin. METHODS: Eleven single-nucleotide polymorphisms (SNPs) from cytokine genes implicated in previous AA studies were genotyped. These genes were IL1B, IL1A, IL1RN, MIF, IFNG and the TNF/LTA gene region. We also genotyped 15 SNPs selected from cytokine genes that have shown significant association with other autoimmune diseases. These genes were IL10, IL36RN, IL12B, IL6, IL2, IL23, IL2RA and IL4R. RESULTS: Significant association was found for two variants within both IL2RA and TNF/LTA. In the overall sample, the most significant results were obtained for the IL2RA variant rs706778 (P = 0·00038) and the TNF/LTA locus variant rs1800629 (P = 0·0017). In subgroup analyses, according to severity, age at onset and family history these effects were stronger in the severely affected patients, with the lowest P-values being obtained for rs706778 (P = 3·8 × 10(-6) ). CONCLUSIONS: Our results point to the involvement of IL2RA and the TNF/LTA region in the aetiology of AA, in particular severe AA, and provide further support for the hypothesis that AA is autoimmune in nature.

Investigation of the male pattern baldness major genetic susceptibility loci AR/EDA2R and 20p11 in female pattern hair loss.

BACKGROUND: The aetiology of female pattern hair loss (FPHL) is largely unknown. However, it is hypothesized that FPHL and male pattern baldness (AGA) share common susceptibility alleles. The two major susceptibility loci for AGA are the androgen receptor (AR)/ectodysplasin A2 receptor (EDA2R) locus on the X-chromosome, and a locus on chromosome 20p11, for which no candidate gene has yet been identified. OBJECTIVES: To examine the role of the AR/EDA2R and 20p11 loci in the development of FPHL using 145 U.K. and 85 German patients with FPHL, 179 U.K. supercontrols and 150 German blood donors. METHODS: Patients and controls were genotyped for 25 single nucleotide polymorphisms (SNPs) at the AR/EDA2R locus and five SNPs at the 20p11 locus. RESULTS: Analysis of the AR/EDA2R locus revealed no significant association in the German sample. However, a nominally significant association for a single SNP (rs1397631) was found in the U.K. sample. Subgroup analysis of the U.K. patients revealed significant association for seven markers in patients with an early onset (P = 0·047 after adjustment for the testing of multiple SNPs by Monte Carlo simulation). No significant association was obtained for the five 20p11 variants, either in the overall samples or in the analysis of subgroups. CONCLUSIONS: The observed association suggests that the AR/EDA2R locus confers susceptibility to early-onset FHPL. Our results do not implicate the 20p11 locus in the aetiology of FPHL.

The TRAF1/C5 locus confers risk for familial and severe alopecia areata.

BACKGROUND: Alopecia areata (AA) is a common hair loss disorder with a complex mode of inheritance. Autoimmune mechanisms are presumed to be crucial aetiologically. It is plausible that a number of autoimmune disorders may share a common genetic background. This phenomenon has been demonstrated in previous studies, which have shown an overlap of susceptibility alleles between AA and other autoimmune disorders. Recent studies have shown that genetic variants on the TRAF1/C5 (tumor necrosis factor receptor-associated factor 1, complement component 5) locus confer susceptibility to rheumatoid arthritis (RA). OBJECTIVES: To examine the role of the TRAF1/C5 locus in the development of AA using a large sample of 1,195 patients with AA and 1280 controls. METHODS: We genotyped the two most significant single nucleotide polymorphisms (SNPs) (rs10818488, rs2416808) from a former RA candidate gene study. After having obtained evidence for association, we performed a fine-mapping study and genotyped the locus with an additional 27 SNPs. RESULTS: While no significant result was obtained for the overall sample, rs2416808 showed significant associations in the analysis of the subgroups with severe AA and with a positive family history. The most significant P-value for rs2416808 was in familial cases (P = 0.004, P(corr) = 0.026). The fine mapping revealed significant associations for four additional SNPs in the analysis of subgroups, with rs2416808 remaining the most significant marker. CONCLUSIONS: Our results point to the involvement of the TRAF1/C5 locus in the aetiology of familial and severe AA, and provide further support for a shared aetiology between AA and other autoimmune disorders.

Signalling processes involved in C-peptide-induced chemotaxis of CD4-positive lymphocytes.

Previous data from our group demonstrated that C-peptide induces chemotaxis of CD4-positive lymphocytes in-vitro, mediated by activation of G-protein and PI 3-kinase gamma, but additional signalling pathways involved in this process remained unexplored. In the present study we further analyze intracellular signalling pathways which lead to C-peptide-induced CD4-positive lymphocyte migration. We provide evidence that C-peptide-induced chemotaxis of CD4-positive lymphocytes is critically dependent on activation of Src-kinase and RhoA, Rac-1 and Cdc42 GTPases. Furthermore, C-peptide stimulates phosphorylation of PAK, LIMK and cofilin downstream of Rac-1 and Cdc42, leading to cofilin inactivation and actin filament stabilization. In addition, C-peptide induces ROCK kinase activity and MLC phosphorylation downstream of RhoA, thereby stimulating myosin mediated cell contraction. In contrast, C-peptide does not activate ERK1/2, p38 or Akt in CD4-positive lymphocytes. Our data support an active role of C-peptide in CD4-positive lymphocyte chemotaxis and elucidate molecular mechanisms in C-peptide-induced cell migration.

[Hereditary pigmentary disorders]. / Genetisch bedingte Pigmentstörungen.

Pigmentation in human skin differs individually and is regulated by more than 100 genes. The discovery of an increasing number of these genes has shed light on the molecular basis and pathogenesis of genetic pigmentary disorders. They are very rare and can be caused by changes in melanocyte number or melanin synthesis as well as development, transport and transfer of melanosomes. Pigmentary disorders can be divided into hyper- and hypopigmentation, of which the distribution can be diffuse or localized. Localized hypopigmentation can be found in piebaldism, Waardenburg syndrome and Tietz syndrome, whereas diffuse forms are typical for oculocutaneous albinism, Hermansky-Pudlak syndrome, Chediak-Higashi syndrome and Griscelli syndrome. Hyperpigmentation can be divided into diffuse, reticular or localized forms. They must be distinguished from endocrinopathies which may show hyperpigmentation, and from poikilodermatous syndromes displaying internal involvement.

Pili annulati: refinement of the locus on chromosome 12q24.33 to a 2.9-Mb interval and candidate gene analysis.

BACKGROUND: Pili annulati is an autosomal dominant hair shaft disorder characterized by alternating light and dark bands in hairs of affected individuals. Recently, a locus for pili annulati was mapped to chromosome 12q24.32-24.33 and recombination events defined a critical region of 9.2 cM (3.9 Mb). OBJECTIVES: The aim of the current study was to narrow the size of the candidate region and to identify the pathogenic mutation for pili annulati by analysing the candidate genes. METHODS: In three families with 90 individuals, including 40 affected subjects, linkage analysis was performed with 13 microsatellite markers in the candidate region on chromosome 12. Candidate genes were analysed for their expression in hair follicles and other tissues by reverse transcriptase-polymerase chain reaction (RT-PCR) and mutation analysis. RESULTS: Multipoint LOD score analysis for all three families confirmed the locus on the long arm of chromosome 12 with a maximum LOD score of 12.26 at marker D12S357. In two families, recombinations were identified which narrowed the region to 2.9 Mb containing 36 genes. We analysed the candidate genes in this region by RT-PCR and found that 24 were expressed in human hair follicles. Based on the result of the expression analysis, DNA sequencing of the coding region of the candidate genes was performed; this did not result in the discovery of a causal mutation. CONCLUSION: We reduced the critical interval of pili annulati to 2.9 Mb and excluded mutations in the coding region of all 36 possible candidate genes by sequence analysis.

Hair interior defect in AKR/J mice.

BACKGROUND: All AKR/J mice have a subtle defect that involves malformation of the central portion of hair fibres that is best visualized under white and polarized light microscopy. AIMS: This study sought to characterize the clinical and ultrastructural features of the hair interior defect (HID) phenotype and to determine the chromosomal localization of the hid mutant gene locus. METHODS: White and polarized light microscopy combined with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the HID phenotype. Complementation testing and gene-linkage studies were performed to map the locus. RESULTS: Using SEM, the hair-fibre structure on the surface was found to be similar to hairs obtained from normal BALB/cByJ+/+and C57BL/6 J+/+mice. There were also no differences in sulphur content. TEM revealed degenerative changes in the medulla similar to that seen by light microscopy. This autosomal recessive mutation is called HID (locus symbol: hid). We mapped the hid locus to the distal end of mouse chromosome 1. No genes reported to cause skin or hair abnormalities are known to be within this interval except for the lamin B receptor (Lbr), which had been excluded previously as the cause of the hid phenotype in AKR/J mice. CONCLUSION: A potentially novel gene or known gene with a novel phenotype resides within this interval, which may shed light on human diseases with defects in the inner structure of the hair fibre.