Mutational Spectrum of the ABCA12 Gene and Genotype-Phenotype Correlation in a Cohort of 64 Patients with Autosomal Recessive Congenital Ichthyosis.

Autosomal recessive congenital ichthyosis (ARCI) is a non-syndromic congenital disorder of cornification characterized by abnormal scaling of the skin. The three major phenotypes are lamellar ichthyosis, congenital ichthyosiform erythroderma, and harlequin ichthyosis. ARCI is caused by biallelic mutations in ABCA12, ALOX12B, ALOXE3, CERS3, CYP4F22, NIPAL4, PNPLA1, SDR9C7, SULT2B1, and TGM1. The most severe form of ARCI, harlequin ichthyosis, is caused by mutations in ABCA12. Mutations in this gene can also lead to congenital ichthyosiform erythroderma or lamellar ichthyosis. We present a large cohort of 64 patients affected with ARCI carrying biallelic mutations in ABCA12. Our study comprises 34 novel mutations in ABCA12, expanding the mutational spectrum of ABCA12-associated ARCI up to 217 mutations. Within these we found the possible mutational hotspots c.4541G>A, p.(Arg1514His) and c.4139A>G, p.(Asn1380Ser). A correlation of the phenotype with the effect of the genetic mutation on protein function is demonstrated. Loss-of-function mutations on both alleles generally result in harlequin ichthyosis, whereas biallelic missense mutations mainly lead to CIE or LI.

Genome sequencing is a sensitive first-line test to diagnose individuals with intellectual disability.

PURPOSE: Individuals with intellectual disability (ID) and/or neurodevelopment disorders (NDDs) are currently investigated with several different approaches in clinical genetic diagnostics. METHODS: We compared the results from 3 diagnostic pipelines in patients with ID/NDD: genome sequencing (GS) first (N = 100), GS as a secondary test (N = 129), or chromosomal microarray (CMA) with or without FMR1 analysis (N = 421). RESULTS: The diagnostic yield was 35% (GS-first), 26% (GS as a secondary test), and 11% (CMA/FMR1). Notably, the age of diagnosis was delayed by 1 year when GS was performed as a secondary test and the cost per diagnosed individual was 36% lower with GS first than with CMA/FMR1. Furthermore, 91% of those with a negative result after CMA/FMR1 analysis (338 individuals) have not yet been referred for additional genetic testing and remain undiagnosed. CONCLUSION: Our findings strongly suggest that genome analysis outperforms other testing strategies and should replace traditional CMA and FMR1 analysis as a first-line genetic test in individuals with ID/NDD. GS is a sensitive, time- and cost-effective method that results in a confirmed molecular diagnosis in 35% of all referred patients.

A retrospective two centre study of Birt-Hogg-Dubé syndrome reveals a pathogenic founder mutation in FLCN in the Swedish population.

Birt-Hogg-Dube syndrome (BHDS) (MIM: 135150) is a rare autosomal dominant disorder with variable penetrance, caused by pathogenic variants in the FLCN gene. Only a few hundreds of families have so far been described in the literature. Patients with BHDS present with three distinct symptoms: fibrofolliculomas, pneumothorax due to lung cyst formation, and increased lifetime risk of kidney tumours. The aim of the current study was to estimate the incidence of BHDS in the Swedish population and further describe the clinical manifestations and their frequency. Splice variant c.779+1G>T was the most common pathogenic variant, found in 57% of the families, suggesting this may be a founder mutation in the Swedish population. This was further investigated using haplotype analysis in 50 families that shared a common haplotype. Moreover, according to gnomAD the carrier frequency of the c.779+1G>T variant has been estimated to be 1/3265 in the Swedish population, however our data suggest that the carrier frequency in the Swedish population may be significantly higher. These findings should raise awareness among physicians of different specialties to patients presenting with fibrofolliculomas, pneumothorax and/or kidney tumours. We also stress the importance of consensus recommendations regarding diagnosis and clinical management of this, not that uncommon, syndrome.

Integration of whole genome sequencing into a healthcare setting: high diagnostic rates across multiple clinical entities in 3219 rare disease patients.

BACKGROUND: We report the findings from 4437 individuals (3219 patients and 1218 relatives) who have been analyzed by whole genome sequencing (WGS) at the Genomic Medicine Center Karolinska-Rare Diseases (GMCK-RD) since mid-2015. GMCK-RD represents a long-term collaborative initiative between Karolinska University Hospital and Science for Life Laboratory to establish advanced, genomics-based diagnostics in the Stockholm healthcare setting. METHODS: Our analysis covers detection and interpretation of SNVs, INDELs, uniparental disomy, CNVs, balanced structural variants, and short tandem repeat expansions. Visualization of results for clinical interpretation is carried out in Scout-a custom-developed decision support system. Results from both singleton (84%) and trio/family (16%) analyses are reported. Variant interpretation is done by 15 expert teams at the hospital involving staff from three clinics. For patients with complex phenotypes, data is shared between the teams. RESULTS: Overall, 40% of the patients received a molecular diagnosis ranging from 19 to 54% for specific disease groups. There was heterogeneity regarding causative genes (n = 754) with some of the most common ones being COL2A1 (n = 12; skeletal dysplasia), SCN1A (n = 8; epilepsy), and TNFRSF13B (n = 4; inborn errors of immunity). Some causative variants were recurrent, including previously known founder mutations, some novel mutations, and recurrent de novo mutations. Overall, GMCK-RD has resulted in a large number of patients receiving specific molecular diagnoses. Furthermore, negative cases have been included in research studies that have resulted in the discovery of 17 published, novel disease-causing genes. To facilitate the discovery of new disease genes, GMCK-RD has joined international data sharing initiatives, including ClinVar, UDNI, Beacon, and MatchMaker Exchange. CONCLUSIONS: Clinical WGS at GMCK-RD has provided molecular diagnoses to over 1200 individuals with a broad range of rare diseases. Consolidation and spread of this clinical-academic partnership will enable large-scale national collaboration.

Meta-Analysis of Mutations in ALOX12B or ALOXE3 Identified in a Large Cohort of 224 Patients.

The autosomal recessive congenital ichthyoses (ARCI) are a nonsyndromic group of cornification disorders that includes lamellar ichthyosis, congenital ichthyosiform erythroderma, and harlequin ichthyosis. To date mutations in ten genes have been identified to cause ARCI: TGM1, ALOX12B, ALOXE3, NIPAL4, CYP4F22, ABCA12, PNPLA1, CERS3, SDR9C7, and SULT2B1. The main focus of this report is the mutational spectrum of the genes ALOX12B and ALOXE3, which encode the epidermal lipoxygenases arachidonate 12-lipoxygenase, i.e., 12R type (12R-LOX), and the epidermis-type lipoxygenase-3 (eLOX3), respectively. Deficiency of 12R-LOX and eLOX3 disrupts the epidermal barrier function and leads to an abnormal epidermal differentiation. The type and the position of the mutations may influence the ARCI phenotype; most patients present with a mild erythrodermic ichthyosis, and only few individuals show severe erythroderma. To date, 88 pathogenic mutations in ALOX12B and 27 pathogenic mutations in ALOXE3 have been reported in the literature. Here, we presented a large cohort of 224 genetically characterized ARCI patients who carried mutations in these genes. We added 74 novel mutations in ALOX12B and 25 novel mutations in ALOXE3. We investigated the spectrum of mutations in ALOX12B and ALOXE3 in our cohort and additionally in the published mutations, the distribution of these mutations within the gene and gene domains, and potential hotspots and recurrent mutations.

Revertant mosaicism repairs skin lesions in a patient with keratitis-ichthyosis-deafness syndrome by second-site mutations in connexin 26.

Revertant mosaicism (RM) is a naturally occurring phenomenon where the pathogenic effect of a germline mutation is corrected by a second somatic event. Development of healthy-looking skin due to RM has been observed in patients with various inherited skin disorders, but not in connexin-related disease. We aimed to clarify the underlying molecular mechanisms of suspected RM in the skin of a patient with keratitis-ichthyosis-deafness (KID) syndrome. The patient was diagnosed with KID syndrome due to characteristic skin lesions, hearing deficiency and keratitis. Investigation of GJB2 encoding connexin (Cx) 26 revealed heterozygosity for the recurrent de novo germline mutation, c.148G > A, p.Asp50Asn. At age 20, the patient developed spots of healthy-looking skin that grew in size and number within widespread erythrokeratodermic lesions. Ultra-deep sequencing of two healthy-looking skin biopsies identified five somatic nonsynonymous mutations, independently present in cis with the p.Asp50Asn mutation. Functional studies of Cx26 in HeLa cells revealed co-expression of Cx26-Asp50Asn and wild-type Cx26 in gap junction channel plaques. However, Cx26-Asp50Asn with the second-site mutations identified in the patient displayed no formation of gap junction channel plaques. We argue that the second-site mutations independently inhibit Cx26-Asp50Asn expression in gap junction channels, reverting the dominant negative effect of the p.Asp50Asn mutation. To our knowledge, this is the first time RM has been reported to result in the development of healthy-looking skin in a patient with KID syndrome.

Drug-Mediated Gene Regulation of Vitamin D3 Metabolism in Primary Human Dermal Fibroblasts.

Vitamin D metabolism was studied in primary human dermal fibroblasts with focus on drug-mediated gene regulation related to adverse side effects of antiretroviral drugs used in HIV therapy. The fibroblasts expressed mRNA for cytochrome P450 (CYP) enzymes catalysing bioactivating (CYP2R1, CYP27A1 and CYP27B1) and catabolic reactions (CYP24A1). The cells produced both 25-hydroxyvitamin D3 and 1α,25-dihydroxyvitamin D3 . The results demonstrate that primary dermal fibroblasts have an active vitamin D3 -metabolizing system. High incidence of low bone mineral density is a concern for HIV-infected patients treated with antiretroviral drugs. Osteomalacia and severe vitamin D deficiency have been reported. We investigated whether drug-mediated gene regulation could be a possible mechanism behind these adverse drug effects. Fibroblasts were treated with different drugs used in HIV therapy, and the 1α,25-dihydroxyvitamin D3 levels and relative mRNA levels for crucial enzymes were determined. Efavirenz, stavudine and ritonavir significantly down-regulated the bioactivating CYP2R1 and up-regulated the catabolic CYP24A1. The drugs reduced bioactivating enzyme activities and cellular levels of 1α,25-dihydroxyvitamin D3 . The current results indicate that effects on gene expression may lead to disturbed vitamin D metabolism and decreased cellular levels of active vitamin D3 . The data are consistent with the impaired bone health in patients treated with certain antiretroviral drugs.

Spectrum of Autosomal Recessive Congenital Ichthyosis in Scandinavia: Clinical Characteristics and Novel and Recurrent Mutations in 132 Patients.

Autosomal recessive congenital ichthyosis (ARCI) represents a heterogeneous group of rare disorders of cornification with 3 major subtypes: harlequin ichthyosis (HI), lamellar ichthyosis (LI) and congenital ichthyosiform erythroderma (CIE). A 4th subtype has also been proposed: pleomorphic ichthyosis (PI), characterized by marked skin changes at birth and subsequently mild symptoms. In nationwide screenings of suspected cases of ARCI in Denmark and Sweden, we identified 132 patients (age range 0.1-86 years) classified as HI (n = 7), LI (n = 70), CIE (n = 17) and PI (n = 38). At birth, a collodion membrane or similar severe hyperkeratosis was reported in almost all patients with HI and LI, and in nearly half of patients with CIE and PI. Persistent ectropion was more common in HI (85%) and LI (57%), than in CIE (35%) and PI (5%). Anhidrosis was a frequent problem in all 4 groups (58-100%). A scoring (0-4) of ichthyosis/ery-thema past infancy showed widely different mean values in the subgroups: HI (3.2/3.1), LI (2.4/0.6), CIE (1.8/1.6), PI (1.1/0.3). Novel or recurrent mutations were found in 113 patients: TGM1 (n = 56), NIPAL4 (n = 15), ALOX12B (n = 15), ABCA12 (n = 8), ALOXE3 (n = 9), SLC27A4 (n = 5), CYP4F22 (n = 3), PNPLA1 (n = 1) and ABHD5 (n = 1). In conclusion, by performing a deep phenotyping and gene screening, ARCI can be definitely diagnosed in 85% of cases in Scandinavia, with a prevalence of 1:100,000 and > 8 different aetiologies.

Self-reported quality of life, anxiety and depression in individuals with Ehlers-Danlos syndrome (EDS): a questionnaire study.

BACKGROUND: Many individuals with Ehlers-Danlos Syndrome (EDS) are hypermobile, suffer from long term pain, and have complex health problems. Since these sometimes have no objective physical signs, individuals with EDS sometimes are referred for psychiatric evaluation. The aim was therefore to identify the level of anxiety and quality of life in a Swedish group of individuals with EDS. METHODS: A postal survey in 2008 was distributed to 365 members over 18 years of the Swedish National EDS Association and 250 with EDS diagnosis responded. Two questionnaires, the Hospital Anxiety and Depression Scale (HADS) and SF-36, were used. A Swedish population study was used to compare results from SF-36. Independent Student's t-test was used to compare differences between groups, possible relationships were tested using Spearman's correlation coefficient and the General Linear Model was used for regression analyses. Higher scores on HADS represent higher levels of anxiety and depression and higher scores on SF-36 represent higher quality of health. RESULTS: Of the respondents 74.8% scored high on anxiety and 22.4% scored high on depression on the HADS. Age, tiredness and back pain was independently associated with the HAD anxiety score in a multiple regression analysis, When comparing the SF-36 scores from the EDS group and a Swedish population group, the EDS group scored significantly lower, indicating lower health-related quality of health than the general population (p < 0.001). CONCLUSIONS: In comparison with a Swedish population group, a lower health-related quality of life was found in the EDS group. Also, higher levels of anxiety and depression were detected in individuals with EDS. The importance to explore the factors behind these results and what initiatives can be taken to alleviate the situation for this group is emphasized.

Palmoplantar keratoderma of the Gamborg-Nielsen type is caused by mutations in the SLURP1 gene and represents a variant of Mal de Meleda.

Palmoplantar keratoderma of the Gamborg-Nielsen type (PPK-GN) is a rare autosomal recessive skin disorder described in patients from Sweden. Mal de Meleda (MDM) is also a rare autosomal recessive inherited PPK first reported in 5 families from the island of Meleda. The 2 conditions phenotypically overlap and are characterised by palmoplantar erythematous hyperkeratotic plaques. The genetic background giving rise to PPK-GN has hitherto been unknown, whereas MDM is known to be caused by mutations in the gene encoding secreted Ly-6/uPAR-related protein 1, SLURP-1. In the present study we scrutinised individuals affected by PPK-GN for mutations in the SLURP1 gene and identified 2 different mutations. Fourteen Swedish patients were homozygous for a previously described mutation, c.43T>C, while one individual was a compound heterozygote with one copy of a novel mutation, c.280T>A, in addition to one copy of the c.43T>C mutation. Hereby we confirm that PPK-GN is an allelic variant of MDM.

BRCA1 R1699Q variant displaying ambiguous functional abrogation confers intermediate breast and ovarian cancer risk.

BACKGROUND: Clinical classification of rare sequence changes identified in the breast cancer susceptibility genes BRCA1 and BRCA2 is essential for appropriate genetic counselling of individuals carrying these variants. We previously showed that variant BRCA1 c.5096G>A p.Arg1699Gln in the BRCA1 transcriptional transactivation domain demonstrated equivocal results from a series of functional assays, and proposed that this variant may confer low to moderate risk of cancer. METHODS: Measures of genetic risk (report of family history, segregation) were assessed for 68 BRCA1 c.5096G>A p.Arg1699Gln (R1699Q) families recruited through family cancer clinics, comparing results with 34 families carrying the previously classified pathogenic BRCA1 c.5095C>T p.Arg1699Trp (R1699W) mutation at the same residue, and to 243 breast cancer families with no BRCA1 pathogenic mutation (BRCA-X). RESULTS: Comparison of BRCA1 carrier prediction scores of probands using the BOADICEA risk prediction tool revealed that BRCA1 c.5096G>A p.Arg1699Gln variant carriers had family histories that were less 'BRCA1-like' than BRCA1 c.5095C>T p.Arg1699Trp mutation carriers (p<0.00001), but more 'BRCA1-like' than BRCA-X families (p=0.0004). Further, modified segregation analysis of the subset of 30 families with additional genotyping showed that BRCA1 c.5096G >A p.Arg1699Gln had reduced penetrance compared with the average truncating BRCA1 mutation penetrance (p=0.0002), with estimated cumulative risks to age 70 of breast or ovarian cancer of 24%. CONCLUSIONS: Our results provide substantial evidence that the BRCA1 c.5096G>A p.Arg1699Gln (R1699Q) variant, demonstrating ambiguous functional deficiency across multiple assays, is associated with intermediate risk of breast and ovarian cancer, highlighting challenges for risk modelling and clinical management of patients of this and other potential moderate-risk variants.

Harlequin ichthyosis: a review of clinical and molecular findings in 45 cases.

OBJECTIVE: To assess the clinical outcomes of 45 cases of harlequin ichthyosis and review the underlying ABCA12 gene mutations in these patients. DESIGN: Multicenter, retrospective, questionnaire-based survey. SETTING: Dermatology research institute. PARTICIPANTS: Patients with harlequin ichthyosis for whom we had performed ABCA12 mutation analysis. MAIN OUTCOME MEASURES: Referring physicians were asked to complete a questionnaire using the patients' notes, detailing the clinical outcome of the affected child. In each case, the causative ABCA12 mutation was identified using standard polymerase chain reaction and sequencing techniques. RESULTS: Of the 45 cases, the ages of the survivors ranged from 10 months to 25 years, with an overall survival rate of 56%. Death usually occurred in the first 3 months and was attributed to sepsis and/or respiratory failure in 75% of cases. The early introduction of oral retinoids may improve survival, since 83% of those treated survived, whereas 76% who were not given retinoids died. Recurrent skin infections in infancy affected one-third of patients. Problems maintaining weight affected 44%. Three children developed an inflammatory arthritis, and developmental delay was reported in 32%. Mutation analysis revealed that 52% of survivors had compound heterozygous mutations, whereas all deaths were associated with homozygous mutations. CONCLUSIONS: Harlequin ichthyosis should be regarded as a severe chronic disease that is not invariably fatal. With improved neonatal care and probably the early introduction of oral retinoids, the number of survivors is increasing. Compound heterozygotes appear to have a survival advantage.

Genotypic and clinical spectrum of self-improving collodion ichthyosis: ALOX12B, ALOXE3, and TGM1 mutations in Scandinavian patients.

Infants born with autosomal recessive congenital ichthyosis (ARCI) are often encapsulated in a collodion membrane, which shows a lamellar or erythrodermic type of ichthyosis upon shedding. However, some babies show a nearly normal underlying skin after several weeks, a phenotype called "self-healing collodion baby" (SHCB). Mutations in two genes, TGM1 and ALOX12B, have previously been implicated in the etiology of SHCB, but the full genotypic spectrum remains to be determined. DNA sequencing in 11 Swedish and 4 Danish SHCB patients showed ALOX12B mutations in eight cases, ALOXE3 mutations in three cases, and TGM1 mutations in one case. In three patients, we could not find mutations in any of the known ARCI genes. In all cases, a spontaneous shedding of the collodion membrane occurred 2-4 weeks after birth. When re-examined at 2-37 years of age, the patients showed skin xerosis, a mild or focal scaling, palmar hyperlinearity with keratoderma, and a frequent appearance of red cheeks and anhidrosis. Thus, we propose replacing SHCB with the term "self-improving collodion ichthyosis" (SICI). In conclusion, ALOX12B mutations are the leading cause of SICI in Scandinavia, followed by ALOXE3 mutations, which have not been previously associated with this variant of ARCI.

The clinical spectrum of congenital ichthyosis in Sweden: a review of 127 cases.

Congenital ichthyosis comprises a rare group of usually monogenetic diseases that present at birth as a collodion phenotype or as variable degrees of ichtHyosiform erythroderma, with or without superficial blisters. Depending on which gene mutation causes the disease, the skin problems later in life may range from a severe lamellar or bullous ichthyosis to mild or only focally expressed hyperkeratotic lesions. It is obviously important, but sometimes painstakingly difficult, to make a correct diagnosis already in infancy. Fortunately, recent advances in our understanding of the molecular genetics of ichthyosis have led to several new diagnostic tools that are continuously being updated. Based on this development, and on our own 5 years of experience in a national genodermatosis centre, we describe 127 cases of congenital ichthyosis examined in childhood or adulthood. Applying a combination of phenotypic and genotypic criteria, the patients were classified into three main groups: 1) Bullous ichthyosis (epidermolytic hyperkeratosis) and related disorders due to keratin mutations (n = 21); 2) Non-bullous ichthyosiform erythroderma and lamellar ichthyosis mainly due to transglutaminase 1 mutations (n = 80); 3) Syndromic ichthyosis, i.e. systemic (multi-organ) diseases due to many different causes (n = 26). Each group could be further stratified into 4-11 entities using mutation analysis, electron microscopy of epidermis and various other techniques. Our findings are discussed in relation to recent data in the literature emphasizing the clinical usefulness of various diagnostic procedures for ichthyosis.

Autosomal recessive congenital ichthyosis in Sweden and Estonia: clinical, genetic and ultrastructural findings in eighty-three patients.

Congenital (non-bullous) ichthyosis is a rare group of keratinizing disorders which can be tentatively subclassified based on clinical criteria, analysis of transglutaminase 1 gene mutations and electron microscopy of epidermis. We studied 83 patients who were all on topical therapy and in 16 cases also on oral retinoids. Three main groups of patients were distinguished: (A) those with transglutaminase 1 gene mutations (n=44), (B) those without transglutaminase 1 gene mutations showing a coarse, generalized scaling (n=19), and (C) those without transglutaminase 1 gene mutations showing only fine or focal scaling (n=20). On clinical scoring, patients in group A were more hyperkeratotic and less erythematous than those in group B (p < 0.05). Anhidrosis was recorded in nearly all patients (> or = 80%), but ectropion and a collodion phenotype at birth were more common in group A versus other groups. Ultrastructurally, a high frequency of type I (Anton-Lamprecht's classification) was found in all three groups (37-63%), 20 cases of type II in group A and a few cases of types III and IV in groups B and C, respectively. In conclusion, transglutaminase 1 gene mutation is a major cause of congenital ichthyosis in Sweden and Estonia, and is often associated with severe scaling and ultrastructural type II in corneocytes. The transglutaminase-unrelated cases are more heterogeneous, probably reflecting a more varied aetiology.