Formation of keto-type ceramides in palmoplantar keratoderma based on biallelic KDSR mutations in patients.

Functional skin barrier requires sphingolipid homeostasis; 3-ketodihydrosphingosine reductase or KDSR is a key enzyme of sphingolipid anabolism catalyzing the reduction of 3-ketodihydrosphingosine to sphinganine. Biallelic mutations in the KDSR gene may cause erythrokeratoderma variabilis et progressive-4, later specified as PERIOPTER syndrome, emphasizing a characteristic periorifical and ptychotropic erythrokeratoderma. We report another patient with compound heterozygous mutations in KDSR, born with generalized harlequin ichthyosis, which progressed into palmoplantar keratoderma. To determine whether patient-associated KDSR mutations lead to KDSR substrate accumulation and/or unrecognized sphingolipid downstream products in stratum corneum (SC), we analyzed lipids of this and previously published patients with non-identical biallelic mutations in KDSR. In SC of both patients, we identified 'hitherto' unobserved skin ceramides with an unusual keto-type sphingoid base in lesional and non-lesional areas, which accounted for up to 10% of the measured ceramide species. Furthermore, an overall shorter mean chain length of free and bound sphingoid bases was observed-shorter mean chain length of free sphingoid bases was also observed in lesional psoriasis vulgaris SC, but not generally in lesional atopic dermatitis SC. Formation of keto-type ceramides is probably due to a bottle neck in metabolic flux through KDSR and a bypass by ceramide synthases, which highlights the importance of tight intermediate regulation during sphingolipid anabolism and reveals substrate deprivation as potential therapy.

Epidermolytic ichthyosis: Clinical spectrum and burden of disease in a large German cohort.

BACKGROUND: Keratinopathic ichthyoses are a group of hereditary skin disorders caused by pathogenic variants in keratin genes such as KRT1, KRT2 and KRT10, resulting in conditions such as epidermolytic ichthyosis (EI), autosomal-recessive EI, superficial EI and epidermal nevus. Case reports highlight the diversity of clinical manifestations, but only limited information exists regarding the quality of life and burden of disease. OBJECTIVES: The objective of this study was to assess the clinical spectrum, genotype-phenotype correlations and burden of disease in patients with epidermolytic ichthyosis in Germany. METHODS: We conducted an observational study involving 48 patients diagnosed with EI. Evaluations included the severity of skin involvement using the Investigator's Global Assessment (IGA), the modified Ichthyosis Area Severity Index (mIASI) and complications. The burden of disease was evaluated using the Dermatology Life Quality Index (DLQI) or the Children's Dermatology Life Quality Index (cDLQI). RESULTS: Based on clinical features, mIASI and IGA, EI can be categorized into localized, intermediate and severe forms. Patients with keratin 1 mutations tended to have severe EI, while the three forms were evenly distributed in those with keratin 10 mutations. The study highlights that around half of the patients with EI experienced itch and severe pain. Quality of life was affected, with daily life restrictions of 78% due to care and therapies. Reimbursement for moisturizing ointments by health insurance was insufficient for one-quarter of cases. CONCLUSIONS: The results emphasize the need for targeted interventions and comprehensive care strategies to enhance the quality of life for affected individuals.

CRISPR-Cas12a for Highly Efficient and Marker-Free Targeted Integration in Human Pluripotent Stem Cells.

The CRISPR-Cas12a platform has attracted interest in the genome editing community because the prototypical Acidaminococcus Cas12a generates a staggered DNA double-strand break upon binding to an AT-rich protospacer-adjacent motif (PAM, 5'-TTTV). The broad application of the platform in primary human cells was enabled by the development of an engineered version of the natural Cas12a protein, called Cas12a Ultra. In this study, we confirmed that CRISPR-Cas12a Ultra ribonucleoprotein complexes enabled allelic gene disruption frequencies of over 90% at multiple target sites in human T cells, hematopoietic stem and progenitor cells (HSPCs), and induced pluripotent stem cells (iPSCs). In addition, we demonstrated, for the first time, the efficient knock-in potential of the platform in human iPSCs and achieved targeted integration of a GFP marker gene into the AAVS1 safe harbor site and a CSF2RA super-exon into CSF2RA in up to 90% of alleles without selection. Clonal analysis revealed bi-allelic integration in >50% of the screened iPSC clones without compromising their pluripotency and genomic integrity. Thus, in combination with the adeno-associated virus vector system, CRISPR-Cas12a Ultra provides a highly efficient genome editing platform for performing targeted knock-ins in human iPSCs.

Inflammasome inhibition protects dopaminergic neurons from α-synuclein pathology in a model of progressive Parkinson's disease.

Neuroinflammation has been suggested as a pathogenetic mechanism contributing to Parkinson's disease (PD). However, anti-inflammatory treatment strategies have not yet been established as a therapeutic option for PD patients. We have used a human α-synuclein mouse model of progressive PD to examine the anti-inflammatory and neuroprotective effects of inflammasome inhibition on dopaminergic (DA) neurons in the substantia nigra (SN). As the NLRP3 (NOD-, LRR- and pyrin domain-containing 3)-inflammasome is a core interface for both adaptive and innate inflammation and is also highly druggable, we investigated the implications of its inhibition. Repeat administration of MCC950, an inhibitor of NLRP3, in a PD model with ongoing pathology reduced CD4+ and CD8+ T cell infiltration into the SN. Furthermore, the anti-inflammasome treatment mitigated microglial activation and modified the aggregation of α-synuclein protein in DA neurons. MCC950-treated mice showed significantly less neurodegeneration of DA neurons and a reduction in PD-related motor behavior. In summary, early inflammasome inhibition can reduce neuroinflammation and prevent DA cell death in an α-synuclein mouse model for progressive PD.

Novel homozygous LAMB1 in-frame deletion in a pediatric patient with brain anomalies and cerebrovascular event.

Biallelic pathogenic variants in LAMB1 have been associated with autosomal recessive lissencephaly 5 (OMIM 615191), which is characterized by brain malformations (cobblestone lissencephaly, hydrocephalus), developmental delay, and epilepsy. Pathogenic variants in LAMB1 are rare, with only 11 pathogenic variants and 11 patients reported to date. Here, we report on a 6-year-old patient from a consanguineous family with profound developmental delay, microcephaly, and a history of a perinatal cerebrovascular event. Brain magnetic resonance imaging (MRI) showed cerebellar cystic defects, signal intensity abnormalities, and a hypoplastic corpus callosum. Trio-exome analysis revealed a homozygous in-frame deletion of Exons 23 and 24 of LAMB1 affecting 104 amino acids including the epidermal growth factor (EGF)-like units 11 and 12 in Domain III. To our knowledge, this is the first reported in-frame deletion in LAMB1. Our findings broaden the clinical and molecular spectrum of LAMB1-associated syndromes.

A homozygous p.Leu813Pro gain-of-function NLRP1 variant causes phenotypes of different severity in two siblings.

BACKGROUND: A trio exome sequencing study identified a previously unreported NLRP1 gene variant resulting in a p.Leu813Pro substitution of the LRR (leucine-rich repeats) domain of the NLRP1 protein (NACHT, LRR and PYD domains-containing protein 1). This homozygous mutation was shared by two sisters with different clinical presentation: the younger sister had generalized inflammatory nodules with keratotic plugs, clinically resembling multiple keratoacanthomas, while the older had manifestations of familial keratosis lichenoides chronica. OBJECTIVES: To analyse the consequences of this NLRP1 variant in two siblings with a different clinical spectrum of severity. METHODS: To demonstrate the pathogenicity, p.Leu813Pro was recombinantly expressed, and its effect on inflammasome assembly was assessed. Exome sequencing and RNA-Seq were performed to identify factors with potentially modifying effects on the severity of the skin manifestation between each sibling. RESULTS: The variant p.Leu813Pro triggered activation of the NLRP1 inflammasome leading to ASC (apoptosis-associated speck-like protein containing a CARD) speck formation and interleukin (IL)-1ß release. The more severely affected sister had several additional genomic variants associated with atopy and psoriasis that were not present in her sibling. IL-5 and IL-17 emerged as dominant cytokines driving prominent inflammation in the skin of the severely affected sibling. CONCLUSIONS: To the best of our knowledge, this is the first report of a NLRP1 variant that leads to a different clinical spectrum of severity within the same sibship. IL-5 and IL-17 were the main cytokines expressed in the inflammatory lesions of the severely affected patient and might be regarded as disease modifying factors, and therefore may be considered as therapeutic targets.

Pathogenic variants in the SPTLC1 gene cause hyperkeratosis lenticularis perstans.

BACKGROUND: Hyperkeratosis lenticularis perstans (HLP), also known as Flegel disease, is a rare skin disease presenting with asymptomatic small hyperkeratotic papules. The lesions often appear on the dorsal feet and lower legs, and typically develop after the fourth decade of life. A genetic basis for HLP is suspected; however, so far no gene defect linked to the development of HLP has been identified. OBJECTIVES: We aimed to identify the genetic cause of HLP. METHODS: For mutational analysis we studied a cohort of five patients with HLP using next-generation sequencing (NGS). We used DNA -extracted from fresh skin biopsies alongside ethylenediamine tetraacetic acid (EDTA) blood samples from two patients, and formalin-fixed -paraffin-embedded skin biopsy material from three patients. In addition, immunofluorescence staining of HLP lesions from four patients was investigated. RESULTS: In all samples from the five patients with HLP we identified by NGS rare variants in the SPTLC1 gene. In four patients we detected small deletions/frameshift variants and in one patient a splicing variant, predicted to disturb the splicing process. In blood samples the detected variants were heterozygous with an allele frequency of 49% and 50%, respectively. In skin biopsies the allele frequency was within the range of 46-62%. Immunofluorescence staining revealed reduced SPTLC1 protein levels in skin of patients. CONCLUSIONS: Our findings suggest that pathogenic variants in the SPTLC1 gene are the underlying genetic cause of HLP. Of note, the identified variants were either frameshift- or splicing variants probably leading to nonsense-mediated mRNA decay and thus reduced SPTLC1 protein levels. We conclude that diminished SPTLC1, the key enzyme in sphingolipid biosynthesis, leads to the development of HLP, which highlights the sphingolipid pathway as a new therapeutic target.

Acral lamellar ichthyosis with amino acid substitution in the C-terminus of keratin 2.

BACKGROUND: Most cases of hereditary ichthyoses present with generalized scaling and skin dryness. However, in some cases skin involvement is restricted to particular body regions as in acral lamellar ichthyosis. OBJECTIVES: We report on the genetic basis of acral ichthyosis in two families presenting with a similar phenotype. METHODS: Genetic testing was performed by targeted next generation sequencing and whole-exome sequencing. For identity-by-descent analysis, the parents were genotyped and data analysis was performed with the Chromosome Analysis Suite Software. RT-PCR with RNA extracted from skin samples was used to analyse the effect of variants on splicing. RESULTS: Genetic testing identified a few heterozygous variants, but only the variant in KRT2 c.1912 T > C, p.Phe638Leu segregated with the disease and remained the strongest candidate. Pairwise identity-by-descent analysis revealed no indication of family relationship. Phenylalanine 638 is the second last amino acid upstream of the termination codon in the tail of K2, and substitution to leucine is predicted as probably damaging. Assessment of the variant is difficult, in part due to the lack of crystal structures of this region. CONCLUSIONS: Altogether, we show that a type of autosomal dominant acral ichthyosis is most probably caused by an amino acid substitution in the C-terminus of keratin 2.

Epidemiology of inherited epidermolysis bullosa in Germany.

BACKGROUND: Epidermolysis bullosa (EB) is a rare genetic disorder manifesting with skin and mucosal membrane blistering in different degrees of severity. OBJECTIVE: Epidemiological data from different countries have been published, but none are available from Germany. METHODS: In this population-based cross-sectional study, people living with EB in Germany were identified using the following sources: academic hospitals, diagnostic laboratories and patient organization. RESULTS: Our study indicates an overall EB incidence of 45 per million live births in Germany. With 14.23 per million live births for junctional EB, the incidence is higher than in other countries, possibly reflecting the availability of early molecular genetic diagnostics in severely affected neonates. Dystrophic EB was assessed at 15.58 cases per million live births. The relatively low incidence found for EB simplex, 14.93 per million live births, could be explained by late or missed diagnosis, but also by 33% of cases remaining not otherwise specified. Using log-linear models, we estimated a prevalence of 54 per million for all EB types, 2.44 for junctional EB, 12.16 for dystrophic EB and 28.44 per million for EB simplex. These figures are comparable to previously reported data from other countries. CONCLUSIONS: Altogether, there are at least 2000 patients with EB in the German population. These results should support national policies and pharmaceutical companies in decision-making, allow more precise planning of drug development and clinical trials, and aid patient advocacy groups in their effort to improve quality of life of people with this orphan disease.

Lipoid proteinosis: Novel ECM1 pathogenic variants and intrafamilial variability in four unrelated Arab families.

BACKGROUND/OBJECTIVES: Lipoid proteinosis (LP) is a rare autosomal recessive multisystem disorder that is caused by loss-of-function pathogenic variants in the extracellular matrix protein-1 (ECM1) gene. The typical clinical manifestations of LP include hoarseness of voice, beaded papules on the eyelids, infiltration and scarring of the skin and mucosa, as well as neuropsychological abnormalities. Currently, more than 70 pathogenic variants have been reported, including nonsense, missense, splice site, deletion and insertion pathogenic variants, and more than half of them occurred in exons 6 and 7. METHODS: Clinical evaluation and Sanger sequencing were performed on eight patients from four unrelated Arab families. RESULTS: We identified two novel ECM1 variants, one nonsense pathogenic variant in exon 6 (c.579G>A, p.Trp193*) and a deletion of three nucleotides (c.1390_1392del, p.Glu464del) in exon 9, and two previously reported frameshift variants; c.692_693delAG, in exon 6 and c.11dupC in exon 1. CONCLUSIONS: Although all patients had characteristic manifestations of lipoid proteinosis, we observed intrafamilial phenotypic variability. Our data expand the pathogenic variant spectrum of ECM1 and also supports the fact that exon 6 is one of the most common hot spots of pathological variants in ECM1.

Germline intergenic duplications at Xq26.1 underlie Bazex-Dupré-Christol basal cell carcinoma susceptibility syndrome.

BACKGROUND: Bazex-Dupré-Christol syndrome (BDCS; MIM301845) is a rare X-linked dominant genodermatosis characterized by follicular atrophoderma, congenital hypotrichosis and multiple basal cell carcinomas (BCCs). Previous studies have linked BDCS to an 11·4-Mb interval on chromosome Xq25-q27.1. However, the genetic mechanism of BDCS remains an open question. OBJECTIVES: To investigate the genetic aetiology and molecular mechanisms underlying BDCS. METHODS: We ascertained multiple individuals from eight unrelated families affected with BDCS (F1-F8). Whole-exome (F1 and F2) and genome sequencing (F3) were performed to identify putative disease-causing variants within the linkage region. Array comparative genomic hybridization and quantitative polymerase chain reaction (PCR) were used to explore copy number variations, followed by long-range gap PCR and Sanger sequencing to amplify the duplication junctions and to define the head-tail junctions. Hi-C was performed on dermal fibroblasts from two affected individuals with BDCS and one control. Public datasets and tools were used to identify regulatory elements and transcription factor binding sites within the minimal duplicated region. Immunofluorescence was performed in hair follicles, BCCs and trichoepitheliomas from patients with BDCS and sporadic BCCs. The ACTRT1 variant c.547dup (p.Met183Asnfs*17), previously proposed to cause BDCS, was evaluated with t allele frequency calculator. RESULTS: In eight families with BDCS, we identified overlapping 18-135-kb duplications (six inherited and two de novo) at Xq26.1, flanked by ARHGAP36 and IGSF1. Hi-C showed that the duplications did not affect the topologically associated domain, but may alter the interactions between flanking genes and putative enhancers located in the minimal duplicated region. We detected ARHGAP36 expression near the control hair follicular stem cell compartment, and found increased ARHGAP36 levels in hair follicles in telogen, in BCCs and in trichoepitheliomas from patients with BDCS. ARHGAP36 was also detected in sporadic BCCs from individuals without BDCS. Our modelling showed the predicted maximum tolerated minor allele frequency of ACTRT1 variants in control populations to be orders of magnitude higher than expected for a high-penetrant ultra-rare disorder, suggesting loss of function of ACTRT1 variants to be an unlikely cause for BDCS. CONCLUSIONS: Noncoding Xq26.1 duplications cause BDCS. The BDCS duplications most likely lead to dysregulation of ARHGAP36. ARHGAP36 is a potential therapeutic target for both inherited and sporadic BCCs. What is already known about this topic? Bazex-Dupré-Christol syndrome (BDCS) is a rare X-linked basal cell carcinoma susceptibility syndrome linked to an 11·4-Mb interval on chromosome Xq25-q27.1. Loss-of-function variants in ACTRT1 and its regulatory elements were suggested to cause BDCS. What does this study add? BDCS is caused by small tandem noncoding intergenic duplications at chromosome Xq26.1. The Xq26.1 BDCS duplications likely dysregulate ARHGAP36, the flanking centromeric gene. ACTRT1 loss-of-function variants are unlikely to cause BDCS. What is the translational message? This study provides the basis for accurate genetic testing for BDCS, which will aid precise diagnosis and appropriate surveillance and clinical management. ARHGAP36 may be a novel therapeutic target for all forms of sporadic basal cell carcinomas.

Telangiectasia-ectodermal dysplasia-brachydactyly-cardiac anomaly syndrome is caused by de novo mutations in protein kinase D1.

BACKGROUND: We describe two unrelated patients who display similar clinical features including telangiectasia, ectodermal dysplasia, brachydactyly and congenital heart disease. METHODS: We performed trio whole exome sequencing and functional analysis using in vitro kinase assays with recombinant proteins. RESULTS: We identified two different de novo mutations in protein kinase D1 (PRKD1, NM_002742.2): c.1774G>C, p.(Gly592Arg) and c.1808G>A, p.(Arg603His), one in each patient. PRKD1 (PKD1, HGNC:9407) encodes a kinase that is a member of the protein kinase D (PKD) family of serine/threonine protein kinases involved in diverse cellular processes such as cell differentiation and proliferation and cell migration as well as vesicle transport and angiogenesis. Functional analysis using in vitro kinase assays with recombinant proteins showed that the mutation c.1808G>A, p.(Arg603His) represents a gain-of-function mutation encoding an enzyme with a constitutive, lipid-independent catalytic activity. The mutation c.1774G>C, p.(Gly592Arg) in contrast shows a defect in substrate phosphorylation representing a loss-of-function mutation. CONCLUSION: The present cases represent a syndrome, which associates symptoms from several different organ systems: skin, teeth, bones and heart, caused by heterozygous de novo mutations in PRKD1 and expands the clinical spectrum of PRKD1 mutations, which have hitherto been linked to syndromic congenital heart disease and limb abnormalities.

Development of a targeted HPLC-ESI-QqQ-MS/MS method for the quantification of sulfolipids from a cyanobacterium, selected leafy vegetables, and a microalgae species.

The use of macro- and microalgae, as well as cyanobacteria, becomes increasingly important for human nutrition, even in Western diets. Health effects, positive as well as negative, are believed to result mainly from minor components in the food. In macro- and microalgae as well as in certain cyanobacteria, one class of such minor compounds is sulfolipids, more precisely sulfoquinovosylmonoacylglycerol (SQMG) and sulfoquinovosyldiacylglycerol (SQDG) derivatives. SQMGs and SQDGs consist of a diacylglycerol esterified with varying fatty acid combinations and a sulfoquinovose moiety. Sulfoquinovose is a sulfonated hexose analogous to D-glucose, but featuring a stable carbon-sulfur bond. With regard to their chemical structure, SQDGs can be distinguished according to their sn1- and sn2-bound fatty acids. Although there is great interest in SQDGs, because of their controversially discussed bioactivities, only a negligible number of comprehensive methods for identification and quantification has been published, so far. Within this work, a sample preparation including a quantitative isolation of SQDGs from selected raw materials, a clean-up with solid-phase extraction (SPE), and a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous identification and quantitation of different, intact SQMGs and SQDGs were developed and validated. The applicability of the method was further demonstrated by comparing a prominent cyanobacterium (Arthrospira sp.) with a microalgae preparation (Chlorella vulgaris), and selected leafy vegetables (spinach, basil).

Vitamin D Status in Distinct Types of Ichthyosis: Importance of Genetic Type and Severity of Scaling.

Data on vitamin D status of patients with inherited ichthyosis in Europe is scarce and unspecific concerning the genetic subtype. This study determined serum levels of 25-hydroxyvitamin D3 (25(OH)D3) in 87 patients with ichthyosis; 69 patients were additionally analysed for parathyroid hormone. Vitamin D deficiency was pronounced in keratinopathic ichthyosis (n = 17; median 25(OH)D3: 10.5 ng/ml), harlequin ichthyosis (n = 2;7.0 ng/ml) and rare syndromic subtypes (n = 3; 7.0 ng/ml). Vitamin D levels were reduced in TG1-proficient lamellar ichthyosis (n = 15; 8.9 ng/ml), TG1-deficient lamellar ichthyosis (n = 12; 11.7 ng/ml), congenital ichthyosiform erythroderma (n = 13; 12.4 ng/ml), Netherton syndrome (n = 7; 10.7 ng/ml) and X-linked ichthyosis (n = 8; 13.9 ng/ml). In ichthyosis vulgaris 25(OH)D3 levels were higher (n = 10; 19.7 ng/ml). Parathyroid hormone was elevated in 12 patients. Low 25(OH)D3 levels were associated with high severity of scaling (p = 0.03) implicating scaling as a risk factor for vitamin D deficiency. Thus, this study supports our recent guidelines for ichthyoses, which recommend screening for and substituting of vitamin D deficiency.

Porokeratosis Plantaris, Palmaris et Disseminata Caused by Con- genital Pathogenic Variants in the MVD Gene and Loss of Hetero-zygosity in Affected Skin.

Porokeratoses are a heterogeneous group of keratinization disorders. For linear porokeratosis and disseminated superficial actinic porokeratosis, a heterozygous pathogenic germline variant in a mevalonate pathway gene and a postzygotic second hit mutation present in affected skin have been shown to be the patho-genetic mechanism for the development of the lesions. However, the molecular mechanism leading to development of porokeratosis plantaris, palmaris et disseminata is not known. This study analysed a cohort of 4 patients with linear porokeratosis and 3 patients with porokeratosis plantaris, palmaris et disseminata, and performed mutation analyses of DNA extracted from blood samples and skin biopsies. All of the study patients carried the heterozygous germline variant c.70+5G>A in the MVD gene. Loss of heterozygosity due to a second hit mutation was found in affected skin of 3 patients with linear porokeratosis and 2 patients with porokeratosis plantaris, palmaris et disseminata. These results suggest that porokeratosis plantaris, palmaris et disseminata shares the same pathogenetic mechanism as other porokeratosis subtypes and belongs to the phenotypic spectrum of MVD-associated porokeratosis.

An Alternative Approach for the Synthesis of Sulfoquinovosyldiacylglycerol.

Sulfoquinovosyldiacylglycerol (SQDG) is a glycolipid ubiquitously found in photosynthetically active organisms. It has attracted much attention in recent years due to its biological activities. Similarly, the increasing demand for vegan and functional foods has led to a growing interest in micronutrients such as sulfolipids and their physiological influence on human health. To study this influence, reference materials are needed for developing new analytical methods and providing enough material for model studies on the biological activity. However, the availability of these materials is limited by the difficulty to isolate and purify sulfolipids from natural sources and the unavailability of chemical standards on the market. Consequently, an alternative synthetic route for the comprehensive preparation of sulfolipids was established. Here, the synthesis of a sulfolipid with two identical saturated fatty acids is described exemplarily. The method opens possibilities for the preparation of a diverse range of interesting derivatives with different saturated and unsaturated fatty acids.

Mutations in SULT2B1 Cause Autosomal-Recessive Congenital Ichthyosis in Humans.

Ichthyoses are a clinically and genetically heterogeneous group of genodermatoses associated with abnormal scaling of the skin over the whole body. Mutations in nine genes are known to cause non-syndromic forms of autosomal-recessive congenital ichthyosis (ARCI). However, not all genetic causes for ARCI have been discovered to date. Using whole-exome sequencing (WES) and multigene panel screening, we identified 6 ARCI-affected individuals from three unrelated families with mutations in Sulfotransferase family 2B member 1 (SULT2B1), showing their causative association with ARCI. Cytosolic sulfotransferases form a large family of enzymes that are involved in the synthesis and metabolism of several steroids in humans. We identified four distinct mutations including missense, nonsense, and splice site mutations. We demonstrated the loss of SULT2B1 expression at RNA and protein levels in keratinocytes from individuals with ARCI by functional analyses. Furthermore, we succeeded in reconstructing the morphologic skin alterations in a 3D organotypic tissue culture model with SULT2B1-deficient keratinocytes and fibroblasts. By thin layer chromatography (TLC) of extracts from these organotypic cultures, we could show the absence of cholesterol sulfate, the metabolite of SULT2B1, and an increased level of cholesterol, indicating a disturbed cholesterol metabolism of the skin upon loss-of-function mutation in SULT2B1. In conclusion, our study reveals an essential role for SULT2B1 in the proper development of healthy human skin. Mutation in SULT2B1 leads to an ARCI phenotype via increased proliferation of human keratinocytes, thickening of epithelial layers, and altered epidermal cholesterol metabolism.

Mutation in ALOX12B likely cause of POI and also ichthyosis in a large Iranian pedigree.

Premature ovarian insufficiency (POI) is a clinically and etiologically heterogeneous disorder characterized by menstrual irregularities and elevated levels of FSH before age of 40 years. Genetic anomalies are among the recognized causes of POI. Here, we aimed to identify the genetic cause of POI in an inbred pedigree with nine POI and two ichthyosis-affected members. Inheritance of POI and ichthyosis were, respectively, dominant and recessive. Reproduction-related information and measurements of relevant hormones were obtained. Genetic studies included homozygosity mapping, linkage analysis, exome sequencing, and screening of candidate variants. A mutation within ALOX12B, which is a known ichthyosis causing gene, was identified as cause of ichthyosis. ALOX12B encodes a protein involved in steroidogenesis and lipid metabolism. Considering the importance of steroidogenesis in reproduction functions, the possibility that the ALOX12B mutation is also cause of POI was considered. Screenings showed that the mutation segregated with POI status. Linkage analysis with respect to POI identified a single strongly linked locus (LOD > 3) that includes ALOX12B. Exome sequencing on POI-affected females identified the mutation in ALOX12B and also a sequence variation in SPNS2 within the linked locus. A possible contribution of the SPNS2 variation to POI was not strictly ruled out, but various data presented in the text including reported association of variations in related gene ALOX12 with menopause-age and role of ALOX12B in atretic bovine follicle formation argue in favor of ALOX12B. It is, therefore, concluded that the mutation in ALOX12B is the likely cause of POI in the pedigree.

Genetics of Inherited Ichthyoses and Related Diseases.

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

Gene Mutation Mapping in a Fatal Case of Phacomatosis Pigmentokeratotica Happle.

is missing (Short communication).