COL7A1 Mutations Research Articles

Craniofacial Bone Mineral Density During Growth in Mice with Osteogenesis Imperfecta (OI)

Osteogenesis imperfecta (OI or “brittle bone” disease) is a genetic connective tissue defect which results in fragile bones and increased fracture rates. OI type III is the severe form of this disorder, resulting from mutations affecting the formation of type I collagen, the structural protein of bone. Defects in the collagen framework of developing bones lead to improper biomineralization and are thought to underlie the gross structural abnormalities seen in patients with OI, such as midfacial hypoplasia, dental malocclusions, and macrocephaly. Low bone mineral density (BMD) in the post-cranial skeleton and brittle teeth have been reported in human patients with OI as well as murine models of the disorder, yet little is known about craniofacial biomineralization in OI. Typically, skeletal mineralization is responsive to the strain environment throughout growth. The aim of this study is to investigate longitudinal changes in craniofacial BMD in a mouse model of OI type III, and to quantify BMD in regions both proximal and distal to the biomechanical forces generated by feeding behaviors. We hypothesize that mice with OI will have lower BMD at weaning than their unaffected littermates, and will maintain this lower BMD throughout growth. We also hypothesize that both genotypes will demonstrate the absolute highest levels of BMD in regions proximal to the bite point, due to the biomechanical forces generated by feeding. To test these hypotheses, we used the homozygous recessive OI murine (OIM-/-), a mouse strain with a COL1A2 mutation that is a model for OI type III, and their unaffected wild-type (WT) littermates. BMD was measured using in-vivo micro-CT scans at weeks 4 (weaning), 10 (adolescence) and 16 (skeletal maturity) using Bruker CTAnalyzer software. BMD was measured in 8 regions of interest encompassing the neurocranium, facial skeleton, and mandible. BMD values were compared between genotypes via Mann-Whitney U test. In general, this study found there is a trend for OIM mice to have lower BMD values in the craniofacial skeleton as compared to WT mice from weaning through skeletal maturity. OIM mice had significantly (p <0.05) lower BMD than WT mice in all 8 regions during week 4. No significant differences were found in BMD between the genotypes during week 10, possible due to low sample sizes at this time point. At week 16, significant differences (p <0.05) were found in BMD at the parietal bone, mandibular symphysis, and maxillary incisor regions between the genotypes, and weak significant differences (p = 0.07) were found in BMD at the temporomandibular joint region. Additionally, absolute BMD for both genotypes (OIM and WT) tended to be higher within facial and mandibular regions proximal to the bite point compared to the neurocranium at skeletal maturity. Currently, there is no cure for OI, but pharmaceutical interventions (e.g. bisphosphonates) focus on increasing BMD to reduce fracture rates. A better understanding of craniofacial mineralization patterns in OI patients could assist in the timing and implementation of these treatments.

Effect of Losartan on Patellar Cartilage Volume Among Patients With Knee Osteoarthritis

Purpose Losartan previously in murine Osteoarthritis (OA) model displaying the heterozygous chondroplasia gene (cho/+), a col11a1 mutation shown reduced cartilage loss in temporomandibular joint (TMJ) condylar and knee joint articular cartilage (Osteoarthritis and Cartilage, 2019, 27; 676-686). Losartan is an angiotensin receptor blocker and an inhibitor of TGF-beta. This cross sectional study explores the effect of losartan on patellar cartilage volume in patients with knee osteoarthritis using publicly available database. Methods Using data from Osteoarthritis Initiative (OAI), we compared patellar cartilage volume in patients with and without losartan. A total of 4796 men and women aged 45-79 years were enrolled into the study primarily consisting of those with knee OA and those at high risk for developing knee OA. Our study focused on the progression sub cohort, which consisted of 1390 subjects with knee OA. This study used three measurement periods; baseline, 12 months and 24 months. Patients with missing data for entire series or part missing data and patients who were taking other angiotensin receptor blocker drugs excluded from analysis. Patients data then divided into losartan group and control group (patients without losartan). Specific data sets for the analysis included of demographics such age, sex, race (Clinical_FNOH, Enrollees), patient drug usage (MIF00), Magnetic Resonance Imaging (MRI) data sets on cartilage volume were used from KMRI_FNIH_Qcart_Biomediq00 (baseline), KMRI_FNIH_Qcart_Biomediq01 (12 months), and KMRI_FNIH_Qcart_Biomediq03 (24 months). The patellar cartilage volume variables were V00PatellarCartilage (baseline), V01PatellarCartilage (12 months) and V03PatellarCartilage (24 months). Additional protocol details are published and available on the internet (https://oai.epi-ucsf.org/datarelease/docs/StudyDesignProtocol.pdf). Results Our analysis of the progression sub cohort included a total of 85 (44 %) were men and 108 (56 %) women with symptomatic knee OA (Total n=193). Average age of the participants was 59.6 years (SD, 8.7 years; range, 45–78 years). The majority of the participants were Caucasian (n=142; 73.6 %) and African American (n=42; 21.8 %) (Table 1). Of the 193 patients included in analysis, 30 patients were taking losartan and remaining 163 patients were placed into control group. Mean cartilage volume for losartan and control groups at baseline, 12 months and 24 months are shown in figure 1. Over the period of two years, there was a progressive decline in cartilage volume in both groups. Our analysis show that there was no significant loss of cartilage volume with patients on losartan over baseline at 12 months (5 %) and 24 months (8 %) post enrollment. Patients without losartan showed significantly higher cartilage loss at 24 months post enrollment over baseline (~15 %, p≤ 0.05, Student's t-test assuming unequal variances). Conclusion This study suggests that losartan reduces loss of patellar cartilage in patients with knee osteoarthritis. Further analysis is needed to ascertain association of losartan and reduced loss of cartilage volume and beneficial effects of losartan in osteoarthritis.

486 Systemic collagen VII protein therapy for treatment of advanced RDEB

Recessive dystrophic epidermolysis bullosa (RDEB) is a genetic skin blistering disease associated with progressive multi-organ fibrosis. RDEB is caused by biallelic COL7A1 mutations leading to reduced production or functionality of the extracellular matrix protein, collagen VII (C7), which is necessary for epidermal-dermal adherence. C7 is not simply a structural protein but also has multiple functions, including regulation of TGFβ bioavailability and the inhibition of skin scarring after wounding. The multi-organ involvement of RDEB calls for systemic treatment. Intriguingly, intravenous (IV) administration of recombinant C7 (rC7) improves the clinical phenotype of newborn C7 deficient mice and rescues them from neonatal lethality. The effect on established RDEB in adult animals has not been determined. Here, we used small and large adult RDEB animal models to investigate the disease-modulating abilities of rC7 on established RDEB. In adult RDEB mice, IV-injected rC7 accumulated dose-dependently at the dermal-epidermal junction of wounded skin and oral mucosa. Bi-weekly IV injections of rC7 for 7 weeks in adult RDEB mice reduced new skin blisters and effectively reduced progression of the fibrotic mitten deformities of their paws. The inhibition of fibrosis was mediated through reduction of TGFβ signaling. IV infusion of rC7 in adult dogs with RDEB also improved disease by promoting the healing of blister-induced skin erosions without excessive scarring. In both models, IV C7 was well tolerated. These preclinical studies suggest that repeated IV administration of rC7 is an efficacious systemic treatment for established adult RDEB.

Generation of two induced pluripotent stem cell lines from patients with X-linked Alport syndrome

Mutations in COL4A5 on chromosome Xq22 cause X-linked Alport syndrome (XLAS). In this study, we generated two human induced pluripotent stem cell (iPSC) lines from two male patients carrying mutation c.796C > T (p.R266X) in COL4A5 gene. The two iPSC lines retain the original mutation, possess normal karyotypes, express pluripotency markers and bear differentiation potential.

A novel de novo mutation in COL1A1 leading to osteogenesis imperfecta confirmed by zebrafish model

SummaryOur study reports a novel dominant COL1A1 mutation in OI. Using a zebrafish model, we confirmed that the glycine to serine substitution at position 608 of the COL1A1 protein has deleterious effects on bone development. PurposeOsteogenesis imperfecta (OI), also known as brittle bone disease, is a group of genetic disorders. Mutations in two genes, collagen type I alpha 1 chain (COL1A1) and collagen type I alpha 1 chain (COL1A2), which encode the pro-a1 (I) and pro-a2 (I) chains of type I collagen, respectively, the most abundant form of collagen in the human body, cause most cases of OI. MethodsIn this study, we used panel-based next-generation sequencing for prenatal diagnosis of a fetus whose ultrasound images suggested OI. A de novo mutation in COL1A1 gene was suspected to cause the phenotype. To validate the effect of this mutation in a zebrafish model, we constructed a plasmid containing the corresponding mutation in the zebrafish gene col1a1a (c.1744 G > A), and overexpressed the mutant protein in zebrafish larvae. ResultsWe identified a novel COL1A1 mutation (c.1822 G > A; p.Gly608Ser) in the fetus but not in her parents by an skeletal dysplasias panel. Bioinformatic analysis showed that the affected residue (p.Gly608) is highly conserved from zebrafish to humans. In contrast to larvae expressing wild-type (WT) col1a1a and enhanced green fluorescent protein (EGFP), col1a1a mutation-expressing larvae showed significant spinal curvature and embryonic lethality, mimicking the phenotype of human OI. ConclusionsOur study revealed the pathogenicity of a de novo mutation, c.1822 G > A, in human COL1A1, which expands the mutation spectrum of OI.

Next-generation sequencing in patients with familial FSGS: first report of collagen gene mutations in Tunisian patients.

Focal segmental glomerulosclerosis (FSGS) is a histological lesion with many causes, including inherited genetic defects, with significant proteinuria being the predominant clinical finding at presentation. FSGS is considered as a podocyte disease due to the fact that in the majority of patients with FSGS, the lesion results from defects in the podocyte structure. However, FSGS does not result exclusively from podocyte-associated genes. In this study, we used a genetic approach based on targeted next-generation sequencing (NGS) of 242 genes to identify the genetic cause of FSGS in seven Tunisian families. The sequencing results revealed the presence of eight distinct mutations including seven newly discovered ones: the c.538G>A (p.V180M) in NPHS2, c.5186G>A (p.R1729Q) in PLCE1 and c.232A>C (p.I78L) in PAX2 and five novel mutations in COL4A3 and COL4A4 genes. Four mutations (c.209G>A (p.G70D), c.725G>A (p.G242E), c.2225G>A (p.G742E), and c. 1681_1698del) were detected in COL4A3 gene and one mutation (c.1424G>A (p.G475D)) was found in COL4A4. In summary, NGS of a targeted gene panel is an ideal approach for the genetic testing of FSGS with multiple possible underlying etiologies. We have demonstrated that not only podocyte genes but also COL4A3/4 mutations should be considered in patients with FSGS.

Differentiation of Hypertrophic Chondrocytes from Human iPSCs for the In Vitro Modeling of Chondrodysplasias

SummaryChondrodysplasias are hereditary diseases caused by mutations in the components of growth cartilage. Although the unfolded protein response (UPR) has been identified as a key disease mechanism in mouse models, no suitable in vitro system has been reported to analyze the pathology in humans. Here, we developed a three-dimensional culture protocol to differentiate hypertrophic chondrocytes from induced pluripotent stem cells (iPSCs) and examine the phenotype caused by MATN3 and COL10A1 mutations. Intracellular MATN3 or COL10 retention resulted in increased ER stress markers and ER size in most mutants, but activation of the UPR was dependent on the mutation. Transcriptome analysis confirmed a UPR with wide-ranging changes in bone homeostasis, extracellular matrix composition, and lipid metabolism in the MATN3 T120M mutant, which further showed altered cellular morphology in iPSC-derived growth-plate-like structures in vivo. We then applied our in vitro model to drug testing, whereby trimethylamine N-oxide led to a reduction of ER stress and intracellular MATN3.

A De Novo Mutation in COL1A1 in a Holstein Calf with Osteogenesis Imperfecta Type II.

Simple SummarySkeletal connective tissue disorders represent a heterogeneous group of inherited disorders mostly monogenically inherited. Heritable connective tissue disorders such as osteogenesis imperfecta (OI) belong to this group. Herein, an affected calf showing congenital bone lesions such as intrauterine fractures, abnormally shaped long bones and localized arthrogryposis resembling OI type II is reported. Whole-genome sequencing (WGS) identified a most likely disease-causing mutation in the COL1A1 gene. The COL1A1 gene is known to be associated with dominant inherited OI type II forms in humans and sporadically in dogs and cattle, but so far, a variant in the fibrillar collagen NC1 domain has not been shown to cause a similar phenotype in domestic animals. We assume that the herein identified most-likely causative variant occurred either within the parental germlines or post-zygotically in the developing embryo. Rare lethal disorders such as OI in livestock are usually not diagnosed to the molecular level, mainly because of the lack of resources and diagnostic tools. WGS-based precision diagnostics allows understanding rare disorders and supports the value of surveillance of cattle breeding populations for harmful genetic disorders.Osteogenesis imperfecta (OI) type II is a genetic connective tissue disorder characterized by bone fragility, severe skeletal deformities and shortened limbs. OI usually causes perinatal death of affected individuals. OI type II diagnosis in humans is established by the identification of heterozygous mutations in genes coding for collagens. The purpose of this study was to characterize the pathological phenotype of an OI type II-affected neonatal Holstein calf and to identify the causative genetic variant by whole-genome sequencing (WGS). The calf had acute as well as intrauterine fractures, abnormally shaped long bones and localized arthrogryposis. Genetic analysis revealed a private heterozygous missense variant in COL1A1 (c.3917T>A) located in the fibrillar collagen NC1 domain (p.Val1306Glu) that most likely occurred de novo. This confirmed the diagnosis of OI type II and represents the first report of a pathogenic variant in the fibrillar collagen NC domain of COL1A1 associated to OI type II in domestic animals. Furthermore, this study highlights the utility of WGS-based precise diagnostics for understanding congenital disorders in cattle and the need for continued surveillance for rare lethal genetic disorders in cattle.

Correction of recessive dystrophic epidermolysis bullosa by homology-directed repair-mediated genome editing

Genome-editing technologies that enable the introduction of precise changes in DNA sequences have the potential to lead to a new class of treatments for genetic diseases. Epidermolysis bullosa (EB) is a group of rare genetic disorders characterized by extreme skin fragility. The recessive dystrophic subtype of EB (RDEB), which has one of the most severe phenotypes, is caused by mutations in COL7A1. In this study, we report a gene-editing approach for ex vivo homology-directed repair (HDR)-based gene correction that uses the CRISPR-Cas9 system delivered as a ribonucleoprotein (RNP) complex in combination with donor DNA templates delivered by adeno-associated viral vectors (AAVs). We demonstrate sufficient mutation correction frequencies to achieve therapeutic benefit in primary RDEB keratinocytes containing different COL7A1 mutations as well as efficient HDR-mediated COL7A1 modification in healthy cord blood-derived CD34+ cells and mesenchymal stem cells (MSCs). These results are a proof of concept for HDR-mediated gene correction in different cell types with therapeutic potential for RDEB.

Signatures of Dermal Fibroblasts from RDEB Pediatric Patients.

The recessive form of dystrophic epidermolysis bullosa (RDEB) is a debilitating disease caused by impairments in the junctions of the dermis and the basement membrane of the epidermis. Mutations in the COL7A1 gene induce multiple abnormalities, including chronic inflammation and profibrotic changes in the skin. However, the correlations between the specific mutations in COL7A1 and their phenotypic output remain largely unexplored. The mutations in the COL7A1 gene, described here, were found in the DEB register. Among them, two homozygous mutations and two cases of compound heterozygous mutations were identified. We created the panel of primary patient-specific RDEB fibroblast lines (FEB) and compared it with control fibroblasts from healthy donors (FHC). The set of morphological features and the contraction capacity of the cells distinguished FEB from FHC. We also report the relationships between the mutations and several phenotypic traits of the FEB. Based on the analysis of the available RNA-seq data of RDEB fibroblasts, we performed an RT-qPCR gene expression analysis of our cell lines, confirming the differential status of multiple genes while uncovering the new ones. We anticipate that our panels of cell lines will be useful not only for studying RDEB signatures but also for investigating the overall mechanisms involved in disease progression.

Generation and characterization of an integration-free iPSC line SDUBMSi006-A from a patient with Alport syndrome caused by COL4A3 gene mutations.

Alport syndrome (AS) is a hereditary kidney disease caused by mutations in COL4A3, COL4A4, or COL4A5 genes. Here we report the generation of an induced pluripotent stem cell line (iPSC) from an AS patient carrying compound heterozygote mutations (c.4243G>C and c.4216G>A) in COL4A3 gene using non-integrative reprogramming technology. The established iPSC line demonstrates hESC morphology, expresses pluripotency markers, has normal karyotype, and is capable of differentiating into all three germ layers in vitro.

Genetic Modifiers of Hereditary Neuromuscular Disorders and Cardiomyopathy.

Novel genetic variants exist in patients with hereditary neuromuscular disorders (NMD), including muscular dystrophy. These patients also develop cardiac manifestations. However, the association between these gene variants and cardiac abnormalities is understudied. To determine genetic modifiers and features of cardiac disease in NMD patients, we have reviewed electronic medical records of 651 patients referred to the Muscular Dystrophy Association Care Center at the University of Cincinnati and characterized the clinical phenotype of 14 patients correlating with their next-generation sequencing data. The data were retrieved from the electronic medical records of the 14 patients included in the current study and comprised neurologic and cardiac phenotype and genetic reports which included comparative genomic hybridization array and NGS. Novel associations were uncovered in the following eight patients diagnosed with Limb-girdle Muscular Dystrophy, Bethlem Myopathy, Necrotizing Myopathy, Charcot-Marie-Tooth Disease, Peripheral Polyneuropathy, and Valosin-containing Protein-related Myopathy. Mutations in COL6A1, COL6A3, SGCA, SYNE1, FKTN, PLEKHG5, ANO5, and SMCHD1 genes were the most common, and the associated cardiac features included bundle branch blocks, ventricular chamber dilation, septal thickening, and increased outflow track gradients. Our observations suggest that features of cardiac disease and modifying gene mutations in patients with NMD require further investigation to better characterize genotype–phenotype relationships.

Endoplasmic reticulum stress and collagenous formation anomalies in vascular-type Ehlers-Danlos syndrome via electron microscopy.

Vascular-type Ehlers-Danlos syndrome (vEDS) is an autosomal-dominant inherited disorder caused by a deficit in collagen III. It results from heterogeneous mutations in the α1 collagen III gene (COL3A1) and is associated with life-threatening complications, even in younger patients. However, the details of the pathogenesis underlying the COL3A1 mutation causing vEDS remain unclear. Here, we focus on anomalies in collagen fiber size and the endoplasmic reticulum (ER) stress response in patients with vEDS using electron microscopy (EM). We discovered that although the infants did not have vEDS, collagenous formations were similar to their samples in vEDS. Moreover, we examined the expression of activating transcription factor 6 (ATF6) as an ER stress marker and cartilage oligomeric matrix protein (COMP) as a binding partner protein for collagen fibrils in the dermis and COL3A1. The expression levels of ATF6 in the vEDS group were significantly higher than in infants and controls; COMP and COL3A1 levels were significantly lower. The fragile collagen fibrils in vEDS might form as a result of ER stress and that small, newly formed collagen fibrils may appear. This research revealed a novel prospect regarding an issue that has been unclear for a long time, which is the reason for the abnormal sizes of collagenous fibrils in vEDS.

Prepubertal Periodontitis in a Patient with Combined Classical and Periodontal Ehlers–Danlos Syndrome

We report an extremely rare case of combined classical and periodontal Ehlers−Danlos syndrome (EDS) with early severe periodontitis and a generalized lack of attached gingiva. A German family with classical EDS was investigated by physical and dental evaluation and exome and Sanger sequencing. Due to the specific periodontal phenotype in the affected child, an additional diagnosis of periodontal EDS was suspected. Physical and genetic examination of two affected and three unaffected family members revealed a family diagnosis of classical EDS with a heterozygous mutation in COL5A1 (c.1502del; p.Pro501Leufs*57). Additional to the major clinical criteria for classical EDS—generalized joint hypermobility, hyperelastic skin, and atrophic scarring —the child aged four years presented with generalized alveolar bone loss up to 80%, early loss of two lower incisors, severe gingival recession, and generalized lack of attached gingiva. Due to these clinical findings, an additional diagnosis of periodontal EDS was suspected. Further genetic analysis revealed the novel missense mutation c.658T>G (p.Cys220Gly) in C1R in a heterozygous state. Early severe periodontitis in association with generalized lack of attached gingiva is pathognomonic for periodontal EDS and led to the right clinical and genetic diagnosis in the present case.

Phenotypic features of dentinogenesis imperfecta associated with osteogenesis imperfecta and COL1A2 mutations

Dentinogenesis imperfecta (DI) requires dental treatment. This study investigated the characteristics of DI teeth associated with osteogenesis imperfecta (OI) and COL1A2 mutations. Whole exome and Sanger sequencing were performed. Three primary teeth (called "OIDI teeth") obtained from 3 unrelated COL1A2 patients were investigated and compared with 9 control teeth from age-matched healthy individuals using colorimetry, micro-computed tomography, Knoop microhardness, energy dispersive X-ray spectroscopy, scanning electron microscopy, and histology. All patients were identified with heterozygous glycine substitutions in COL1A2. The COL1A2 mutations, c.1531G>T and c.2027G>T, were de novo, whereas c.3106G>C was inherited. OIDI1, 2, and 3 teeth had a substantial decrease in dentin microhardness and lightness. OIDI2 enamel microhardness was significantly reduced, whereas OIDI1 and 3 had enamel microhardness comparable to that of control individuals. The OIDI1 pulp cavity was large; OIDI2 was narrow; and OIDI3 was obliterated. OIDI1 and 3 had significantly higher carbon levels than those in control individuals. Numerous ectopic calcified masses, sparse and obstructed dentinal tubules, dentin holes, and collagen disorientation were observed. OIDI teeth had reduced lightness and variable pulp morphology. Weak dentin, mineral disproportion, and abnormal ultrastructure could contribute to the brittleness of OIDI teeth and adhesive restoration failure. Here, we expand the phenotypic spectrum of COL1A2 mutations and raise awareness among dentists seeing patients with OI.

Alport Syndrome: A Comprehensive Review on Genetics, Pathophysiology, Histology, Clinical and Therapeutic Perspectives.

Alport syndrome (AS) is a disease caused by mutations in COL4A3, COL4A4 or COL4A5, the genes that encode distinct chains of type IV collagen. The vast majority of cases present as an inherited disorder, although de novo mutations are present in around 10% of the cases. This non-systematic review summarizes recent evidence on AS. We discuss the genetic and pathophysiology of AS, clinical manifestations, histopathology, diagnostic protocols, conventional treatment and prognostic markers of the disease. In addition, we summarize experimental findings with novel therapeutic perspectives for AS. The deficient synthesis of collagen heterotrimers throughout the organism leads to impaired basement membranes (BM) in several organs. As a result, the disease manifests in a wide range of conditions, particularly renal, ocular and auricular alterations. Moreover, leiomyomatosis and vascular abnormalities may also be present as atypical presentations. In this framework, diagnosis can be performed based on clinical evaluation, skin or renal biopsy and genetic screening, the latter being the gold standard. There are no formally approved treatments for AS, even though therapeutic options have been described to delay disease progression and increase life expectancy. Novel therapeutic targets under pre-clinical investigation included paricalcitol, sodium-glucose co-transporter- 2 inhibitors, bardoxolone methyl, anti-microRNA-21 oligonucleotides, recombinant human pentraxin-2, lysyl oxidase-like-2 blockers, hydroxypropyl-b-cyclodextrin, sodium 4-phenylbutyrate and stem cell therapy. AS is still a greatly under and misdiagnosed disorder. The pathophysiology is still not fully understood and genetics of the disease also have some gaps. Up to know, there is no specific and effective treatment for AS. Further studies are necessary to establish novel and effective therapeutic protocols.

NPHS2 gene polymorphism aggravates renal damage caused by focal segmental glomerulosclerosis with COL4A3 mutation.

Focal segmental glomerulosclerosis (FSGS), a type of primary glomerular disease, is the leading cause of end-stage renal disease (ESRD). Several studies have revealed that certain single-gene mutations are involved in the pathogenesis of FSGS; however, the main cause of FSGS has not been fully elucidated. Homozygous mutations in the glomerular basement membrane gene can lead to early renal failure, while heterozygous carriers develop renal failure symptoms late. Here, molecular genetic analysis of clinical information collected from clinical reports and medical records was performed. Results revealed that nephrosis 2 (NPHS2) gene polymorphism aggravated renal damage in three FSGS families with heterozygous COL4A3 mutation, leading to early renal failure in index patients. Our findings suggest that COL4A3 and NPHS2 may have a synergistic effect on renal injury caused by FSGS. Further analysis of the glomerular filtration barrier could help assess the cause of kidney damage. Moreover, a detailed analysis of the glomerular basement membrane-related genes and podocyte structural proteins may help us better understand FSGS pathogenesis and provide insights into the prognosis and treatment of hereditary glomerulonephropathy.

Epidermolysis Bullosa in Chinese Patients: Genetic Analysis and Mutation Landscape in 57 Pedigrees and Sporadic Cases.

Epidermolysis bullosa encompasses a group of inherited blistering skin disorders. The pathogenic mutations in 10–25% of patients with epidermolysis bullosa have not been identified by Sanger sequencing. The aims of this study were to identify the pathogenic sequence alterations in a large cohort of Chinese patients with epidermolysis bullosa and to clarify the relationship between clinical phenotypes and genotypes. Whole-exome sequencing was performed on 44 pedigrees and 13 sporadic cases. The results were further confirmed by Sanger sequencing. In total, 52 mutations, comprising 19 novel and 33 previously reported mutations, were identified in 5 genes, with a mutation detection rate of 100%. A relationship between subtypes and pathogenic genes was established: 12 cases of epidermolysis bullosa simplex were associated with mutations in KRT5/14 and PLEC; one case of junctional epidermolysis bullosa carried mutations in ITGB4; and 44 cases of dystrophic epidermolysis bullosa were caused by mutations in COL7A1. The results of this study support whole-exome sequencing as a promising tool in the genetic diagnosis of epidermolysis bullosa.

Identifying Driver Genes Mutations with Clinical Significance in Thyroid Cancer

Advances in technology are enabling gene mutations in papillary thyroid carcinoma (PTC) to be analyzed and clinical outcomes, such as recurrence, to be predicted. To date, the most common genetic mutation in PTC is in BRAF kinase (BRAF). However, whether mutations in other genes coincide with those in BRAF remains to be clarified. The aim of this study was to find mutations in other genes that co-exist with mutated BRAF, and to analyze their frequency and clinical relevance in PTC. Clinical and genetic data were collected from 213 PTC patients with a total of 36,572 mutation sites in 735 genes. After matching with genes from PTC entries in a global database (NCBI Gene), 69 genes with mutations in coding regions were chosen for further study. Through frequency-based analysis, we identified commonly mutated genes co-existing with mutated BRAF and, using the mutation count correlation matrix (MCCM) method, analyzed their incidence according to age and gender. We designed Chord diagrams to reveal gene relationships concerning age and gender, and found that mutations in ALK, ATM, COL1A1, MSTIR, PRKCA, and WNK1 most commonly coincide with mutated BRAF, followed by APC, AURKA, and AURKB. These findings provide further insight into the genetic profile of PTC.

Deciphering the pathogenesis of the COL4-related hematuric nephritis: A genotype/phenotype study.

BackgroundAlport syndrome (ATS) is a hereditary progressive hematuric nephropathy associated with sensorineural deafness and ocular abnormalities, which is caused by mutations in the COL4A5 gene (X‐linked ATS) and in two autosomal genes, COL4A4 and COL4A3, responsible of both recessive ATS and, when present in heterozygosity, of a spectrum of phenotypes ranging from isolated hematuria to frank renal disease.MethodsRetrospective analysis of the clinical and genetic features of 76 patients from 34 unrelated ATS families (11 with mutations in COL4A5, 11 in COL4A3, and 12 in COL4A4) and genotype/phenotype correlation for the COL4A3/COL4A4 heterozygotes (34 patients from 14 families).ResultsEight (24%) of the 34 heterozygous COL4A3 and COL4A4 carriers developed renal failure at a mean age of 57 years, with a significantly lower risk than hemizygous COL4A5 or double heterozygous COL4A3/COL4A4 carriers (p < 0.01), but not different from that of the heterozygous COL4A5 females (p = 0.6). Heterozygous carriers of frameshift/splicing variants in COL4A3/COL4A4 presented a higher risk of developing renal failure than those with missense variants in the glycine domains (p = 0.015).ConclusionThe renal functional prognosis of patients with COL4A3/COL4A4‐positive ATS recapitulates that of the X‐linked ATS forms, with differences between heterozygous vs. double heterozygous patients and between carriers of loss‐of‐function vs. missense variants.