Exome-wide benchmark of difficult-to-sequence regions using short-read next-generation DNA sequencing.

Next-generation DNA sequencing (NGS) in short-read mode has recently been used for genetic testing in various clinical settings. NGS data accuracy is crucial in clinical settings, and several reports regarding quality control of NGS data, primarily focusing on establishing NGS sequence read accuracy, have been published thus far. Variant calling is another critical source of NGS errors that remains unexplored at the single-nucleotide level despite its established significance. In this study, we used a machine-learning-based method to establish an exome-wide benchmark of difficult-to-sequence regions at the nucleotide-residue resolution using 10 genome sequence features based on real-world NGS data accumulated in The Genome Aggregation Database (gnomAD) of the human reference genome sequence (GRCh38/hg38). The newly acquired metric, designated the 'UNMET score,' along with additional lines of structural information from the human genome, allowed us to assess the sequencing challenges within the exonic region of interest using conventional short-read NGS. Thus, the UNMET score could provide a basis for addressing potential sequential errors in protein-coding exons of the human reference genome sequence GRCh38/hg38 in clinical sequencing.

Suspected malnutrition-induced reversible feline skin fragility syndrome in a cat with congenital axial deformities.

A stray cat, an intact female Japanese domestic shorthair cat of unknown age (suspected to be a young adult), was rescued. The cat was lethargic and thin and had marked skin fragility, delayed wound healing without skin hyperextensibility, and hind limb proprioceptive ataxia and paresis. Survey radiography, computed tomography, and magnetic resonance imaging revealed congenital vertebral anomalies, including thoracolumbar transitional vertebrae, scoliosis resulting from a thoracic lateral wedge-shaped vertebra, and a kinked tail, and a dilated spinal cord central canal. Through nutritional support, the cat's general condition normalized, followed by a gradual and complete improvement of skin features. Whole-genome sequencing was completed; however, no pathogenic genetic variant was identified that could have caused this phenotype, including congenital scoliosis. A skin biopsy obtained 7 y after the rescue revealed no remarkable findings on histopathology or transmission electron microscopy. Based on clinical course and microscopic findings, malnutrition-induced reversible feline skin fragility syndrome (FSFS) was suspected, and nutritional support was considered to have improved the skin condition. Key clinical message: This is the second reported case of presumed malnutrition-induced reversible FSFS and was accompanied by long-term follow-up.

Syndrome de fragilité cutanée réversible induit par la malnutrition soupçonné chez un chat avec des difformités axiales congénitales. Un chat errant, une femelle intacte de race japonaise à poil court et d'âge inconnu (suspecté être une jeune adulte), a été secourue. La chatte était léthargique et maigre, et avait une fragilité marquée de la peau, un retard dans la guérison de plaies sans hyperextensibilité de la peau, et une ataxie proprioceptive et parésie des membres postérieurs. Des radiographies, un examen par tomodensitométrie, et de l'imagerie par résonnance magnétique ont révélé des anomalies congénitales des vertèbres, incluant des vertèbres transitionnelles thoraco-lombaires, une scoliose résultant d'une vertèbre thoracique en forme de coin, une queue pliée, et un canal central de la moelle épinière dilaté. Grâce à un soutien nutritionnel, la condition générale du chat s'est stabilisée, suivi d'une amélioration graduelle et complète des caractéristiques de la peau. Le séquençage du génome complet a été effectué; toutefois, aucune variation génétique pathogénique n'a été identifiée qui aurait pu causer ce phénotype, incluant la scoliose congénitale. Une biopsie cutanée obtenue 7 j après le sauvetage n'a révélé aucune trouvaille spéciale à l'histopathologie ou par microscopie électronique à transmission. Basé sur le déroulement clinique et l'examen microscopique, le syndrome de fragilité cutanée réversible félin induit par la malnutrition (FSFS) était suspecté, et le soutien nutritionnel a été considéré comme ayant amélioré la condition cutanée.Message clinique clé :Ce cas est le deuxième cas rapporté de FSFS induit par la malnutrition soupçonné et a fait l'objet d'un suivi à long terme.(Traduit par Dr Serge Messier).

Homozygous splice site variant affecting the first von Willebrand factor A domain of COL12A1 in a patient with myopathic Ehlers-Danlos syndrome.

Myopathic Ehlers-Danlos syndrome (mEDS) is a subtype of EDS that is caused by abnormalities in COL12A1. Up-to-date, 24 patients from 15 families with mEDS have been reported, with 14 families showing inheritance in an autosomal dominant manner and one family in an autosomal recessive manner. We encountered an additional patient with autosomal recessive mEDS. The patient is a 47-year-old Japanese man, born to consanguineous parents with no related features of mEDS. After birth, he presented with hypotonia, weak spontaneous movements, scoliosis, and torticollis. He had soft palms but no skin hyperextensibility or fragility. Progressive scoliosis, undescended testes, and muscular torticollis required surgery. During adulthood, he worked normally and had no physical concerns. Clinical exome analysis revealed a novel homozygous variant in COL12A1 (NM_004370.6:c.395-1G > A) at the splice acceptor site of exon 6, leading to in-frame skipping of exon 6. The patient was diagnosed with mEDS. The milder manifestations in the current patient compared with previously reported patients with mEDS might be related to the site of the variant. The variant is located in the genomic region encoding the first von Willebrand factor A domain, which affects only the long isoform of collagen XII, in contrast to the variants in previously reported mEDS patients that affected both the long and short isoforms. Further studies are needed to delineate comprehensive genotype-phenotype correlation of the disorder.

Comprehensive genetic screening for vascular Ehlers-Danlos syndrome through an amplification-based next-generation sequencing system.

Vascular Ehlers-Danlos syndrome (vEDS) is a hereditary connective tissue disorder (HCTD) characterized by arterial dissection/aneurysm/rupture, sigmoid colon rupture, or uterine rupture. Diagnosis is confirmed by detecting heterozygous variants in COL3A1. This is the largest Asian case series and the first to apply an amplification-based next-generation sequencing through custom panels of causative genes for HCTDs, including a specific method of evaluating copy number variations. Among 429 patients with suspected HCTDs analyzed, 101 were suspected to have vEDS, and 33 of them (32.4%) were found to have COL3A1 variants. Two patients with a clinical diagnosis of Loeys-Dietz syndrome and/or familial thoracic aortic aneurysm and dissection were also found to have COL3A1 variants. Twenty cases (57.1%) had missense variants leading to glycine (Gly) substitutions in the triple helical domain, one (2.9%) had a missense variant leading to non-Gly substitution in this domain, eight (22.9%) had splice site alterations, three (8.6%) had nonsense variants, two (5.7%) had in-frame deletions, and one (2.9%) had a multi-exon deletion, including two deceased patients analyzed with formalin-fixed and paraffin-embedded samples. This is a clinically useful system to detect a wide spectrum of variants from various types of samples.

Clinical and molecular features of 66 patients with musculocontractural Ehlers-Danlos syndrome caused by pathogenic variants in CHST14 (mcEDS-CHST14).

BACKGROUND: Musculocontractural Ehlers-Danlos syndrome is caused by biallelic loss-of-function variants in CHST14 (mcEDS-CHST14) or DSE (mcEDS-DSE). Although 48 patients in 33 families with mcEDS-CHST14 have been reported, the spectrum of pathogenic variants, accurate prevalence of various manifestations and detailed natural history have not been systematically investigated. METHODS: We collected detailed and comprehensive clinical and molecular information regarding previously reported and newly identified patients with mcEDS-CHST14 through international collaborations. RESULTS: Sixty-six patients in 48 families (33 males/females; 0-59 years), including 18 newly reported patients, were evaluated. Japanese was the predominant ethnicity (27 families), associated with three recurrent variants. No apparent genotype-phenotype correlation was noted. Specific craniofacial (large fontanelle with delayed closure, downslanting palpebral fissures and hypertelorism), skeletal (characteristic finger morphologies, joint hypermobility, multiple congenital contractures, progressive talipes deformities and recurrent joint dislocation), cutaneous (hyperextensibility, fine/acrogeria-like/wrinkling palmar creases and bruisability) and ocular (refractive errors) features were observed in most patients (>90%). Large subcutaneous haematomas, constipation, cryptorchidism, hypotonia and motor developmental delay were also common (>80%). Median ages at the initial episode of dislocation or large subcutaneous haematoma were both 6 years. Nine patients died; their median age was 12 years. Several features, including joint and skin characteristics (hypermobility/extensibility and fragility), were significantly more frequent in patients with mcEDS-CHST14 than in eight reported patients with mcEDS-DSE. CONCLUSION: This first international collaborative study of mcEDS-CHST14 demonstrated that the subtype represents a multisystem disorder with unique set of clinical phenotypes consisting of multiple malformations and progressive fragility-related manifestations; these require lifelong, multidisciplinary healthcare approaches.

Clinical and pathophysiological delineation of musculocontractural Ehlers-Danlos syndrome caused by dermatan sulfate epimerase deficiency (mcEDS-DSE): A detailed and comprehensive glycobiological and pathological investigation in a novel patient.

Musculocontractural Ehlers-Danlos syndrome caused by dermatan sulfate epimerase deficiency (mcEDS-DSE) is a rare connective tissue disorder. This is the first report describing the detailed and comprehensive clinical and pathophysiological features of mcEDS-DSE. The patient, with a novel homozygous nonsense variant (NM_013352.4:c.2601C>A:p.(Tyr867*)), exhibited mild skin hyperextensibility without fragility and small joint hypermobility, but developed recurrent large subcutaneous hematomas. Dermatan sulfate (DS) moieties on chondroitin sulfate/DS proteoglycans were significantly decreased, but remained present, in skin fibroblasts. Electron microscopy examination of skin specimens, including cupromeronic blue-staining to visualize glycosaminoglycan (GAG) chains, revealed coexistence of normally assembled collagen fibrils with attached curved GAG chains and dispersed collagen fibrils with linear GAG chains from attached collagen fibrils across interfibrillar spaces to adjacent fibrils. Residual activity of DS-epi1, encoded by DSE, and/or compensation by DS-epi2, a minor homolog of DS-epi1, may contribute to the mild skin involvement through this "mosaic" pattern of collagen fibril assembly.

Genome sequencing and RNA sequencing of urinary cells reveal an intronic FBN1 variant causing aberrant splicing.

Exome sequencing and panel testing have improved diagnostic yield in genetic analysis by comprehensively detecting pathogenic variants in exonic regions. However, it is important to identify non-exonic pathogenic variants to further improve diagnostic yield. Here, we present a female proband and her father who is diagnosed with Marfan syndrome, a systemic connective tissue disorder caused by pathogenic variants in FBN1. There are also two affected individuals in the siblings of the father, indicating the genetic basis in this family. However, panel testing performed by two institutions reported no causal variants. To further explore the genetic basis of the family, we performed genome sequencing of the proband and RNA sequencing of urinary cells derived from urine samples of the proband and her father because FBN1 is strongly expressed in urinary cells though it is poorly expressed in peripheral blood mononuclear cells. Genome sequencing identified a rare intronic variant (c.5789-15G>A) in intron 47 of FBN1 (NM_000138.4), which was transmitted from her father. RNA sequencing revealed allelic imbalance (monoallelic expression) of FBN1, retention of intron 47, and fewer aberrant transcripts utilizing new acceptor sites within exon 48, which were confirmed by RT-PCR. These results highlighted urinary cells as clinically accessible tissues for RNA sequencing if disease-causing genes are not sufficiently expressed in the blood, and the usefulness of multi-omics analysis for molecular diagnosis of genetic disorders.

Clinical and molecular features of patients with COL1-related disorders: Implications for the wider spectrum and the risk of vascular complications.

Abnormalities in type I procollagen genes (COL1A1 and COL1A2) are responsible for hereditary connective tissue disorders including osteogenesis imperfecta (OI), specific types of Ehlers-Danlos syndrome (EDS), and COL1-related overlapping disorder (C1ROD). C1ROD is a recently proposed disorder characterized by predominant EDS symptoms of joint and skin laxity and mild OI symptoms of bone fragility and blue sclera. Patients with C1ROD do not carry specific variants for COL1-related EDS, including classical, vascular, cardiac-valvular, and arthrochalasia types. We describe clinical and molecular findings of 23 Japanese patients with pathogenic or likely pathogenic variants of COL1A1 or COL1A2, who had either OI-like or EDS-like phenotypes. The final diagnoses were OI in 17 patients, classical EDS in one, and C1ROD in five. The OI group predominantly experienced recurrent bone fractures, and the EDS group primarily showed joint hypermobility and skin hyperextensibility, though various clinical and molecular overlaps between OI, COL1-related EDS, and C1ROD as well as intrafamilial phenotypic variabilities were present. Notably, life-threatening vascular complications (vascular dissections, arterial aneurysms, subarachnoidal hemorrhages) occurred in seven patients (41% of those aged >20 years) with OI or C1ROD. Careful lifelong surveillance and intervention regarding bone and vascular fragility could be required.

A patient with Silver-Russell syndrome with multilocus imprinting disturbance, and Schimke immuno-osseous dysplasia unmasked by uniparental isodisomy of chromosome 2.

Silver-Russell syndrome (SRS) is a congenital disorder characterized by prenatal and postnatal growth failure and craniofacial features. Hypomethylation of the H19/IGF2:IG-differential methylated region (H19LOM) is observed in 50% of SRS patients, and 15% of SRS patients with H19LOM had multilocus imprinting disturbance (MLID). Schimke immuno-osseous dysplasia (SIOD), characterized by spondyloepiphyseal dysplasia and nephropathy, is an autosomal recessive disorder caused by mutations in SMARCAL1 on chromosome 2. We report a patient with typical SRS-related features, spondyloepiphyseal dysplasia, and severe nephropathy. Molecular analyses showed H19LOM, paternal uniparental isodisomy of chromosome 2 (iUPD(2)pat), and a paternally inherited homozygous frameshift variant in SMARCAL1. Genome-wide methylation analysis showed MLID in this patient, although it showed no MLID in another patient with SIOD without SRS phenotype. These results suggest that iUPD(2)pat unmasked the recessive mutation in SMARCAL1 and that the SMARCAL1 gene mutation may have no direct effect on the patient's methylation defects.

Heterozygous missense variant in TRPC6 in a boy with rapidly progressive infantile nephrotic syndrome associated with diffuse mesangial sclerosis.

Transient receptor potential channel C6 encoded by TRPC6 is involved in slit diaphragm formation in podocytes, and abnormalities of the TRPC6 protein cause various glomerular diseases. The first identified pathogenic variant of TRPC6 was found to cause steroid-resistant nephrotic syndrome that typically developed in adulthood and then slowly led to end-stage renal disease, along with a renal pathology of focal segmental glomerulosclerosis. Here, we report a patient with rapidly progressing infantile nephrotic syndrome and a heterozygous missense TRPC6 variant. The patient, a 2-year-old Japanese boy, developed steroid-resistant nephrotic syndrome at age 11 months. His renal function deteriorated rapidly, and peritoneal dialysis was introduced at age 1 year and 6 months. His renal pathology, obtained at age 1 year and 1 month, was consistent with diffuse mesangial sclerosis (DMS). Clinical exome analysis and custom panel analysis for hereditary renal diseases revealed a reported heterozygous missense variant in TRPC6 (NM_004621.5:c.523C > T:p.Arg175Trp). This is the first report of a patient with a TRPC6-related renal disorder associated with DMS.

PIEZO2 deficiency is a recognizable arthrogryposis syndrome: A new case and literature review.

PIEZO2 encodes a mechanically activated cation channel, which is abundantly expressed in dorsal root ganglion neuron and sensory endings of proprioceptors required for light touch sensation and proprioception in mice. Biallelic loss-of-function mutations in PIEZO2 (i.e., PIEZO2 deficiency) were recently found to cause an arthrogryposis syndrome. Sixteen patients from eight families have been reported to date. Herein we report a new case, including detailed clinical characteristics and courses as well as comprehensive neurological features. The patient was a 12-year-old girl presenting with congenital multiple contractures, progressive severe scoliosis, prenatal-onset growth impairment, motor developmental delay with hypotonia and myopathy-like muscle pathology, mild facial features, and normal intelligence. Her neurological features included areflexia, impaired proprioception, and decreased senses. Neurophysiological examination revealed decreased amplitude of sensory nerve action potentials, absent H reflex, and prolongation of central conduction times. Clinical exome sequencing revealed a novel homozygous frameshift mutation in PIEZO2 (NM_022068: c.4171_4174delGTCA: p.Val1391Lysfs*39) with no detectable mRNA expression of the gene. PIEZO2 deficiency represents a clinical entity involving characteristic neuromuscular abnormalities and physical features. Next generation sequencing-based comprehensive molecular screening and extensive neurophysiological examination could be valuable for diagnosis of the disorder.

Peripartum Iliac Arterial Aneurysm and Rupture in a Patient with Vascular Ehlers-Danlos Syndrome Diagnosed by Next-Generation Sequencing.

Vascular Ehlers-Danlos syndrome (vEDS), a genetic disorder caused by mutations in procollagen type III gene (COL3A1), may lead to fatal vascular complication during peripartum period because of the arterial fragility. We experienced a case of vEDS with peripartum life-threatening arterial rapture diagnosed by next-generation sequencing (NGS) and successfully treated the vascular complications. A 25-year-old female in pregnancy at 34 weeks had sudden and acute pain in the left lower abdomen. After successful delivery, her computed tomography scan showed a dissecting aneurysm of the left common iliac artery (CIA). Four days after delivery, she presented in hemorrhagic shock induced by arterial rupture in the CIA. Since her clinical presentations inferred vEDS even in the absence of familial history, we performed NGS-based genetic screening for inherited connective tissue disorders including vEDS with informed consent. Even though we started intensive medication, her iliac aneurysm was progressively enlarging within 3 weeks. After an urgent molecular diagnosis for vEDS (a splice-site mutation), cautious endovascular therapy for her CIA aneurysm was successfully performed. This is the first report for pretreatment molecular diagnosis of vEDS using NGS in an emergent situation of severe vascular complications.

[Successful treatment of X-linked sideroblastic anemia with ALAS2 R452H mutation using vitamin B6].

A 45-year-old man presented with fatigue and pain in the finger joints. Despite having a history of suspected sideroblastic anemia since the age of 18 years, he had not been followed up for years. Upon presentation, laboratory data revealed microcytic anemia and elevated serum ferritin levels. In addition, ringed sideroblasts were increased in the bone marrow. A liver biopsy revealed hemochromatosis and cirrhosis. Furthermore, genetic analysis revealed that he harbored the ALAS2 R452H mutation, leading to the diagnosis of X-linked sideroblastic anemia (XLSA). Accordingly, oral folate or vitamin (Vit) B12 was administered, but his anemia did not respond. However, his hemoglobin level increased from 7 to 11 g/dl with an additional prescription of oral VitB6, which facilitated the patient to undergo phlebotomy to ameliorate organ dysfunctions caused by iron overload. Previous research has revealed that ALAS2 R452 mutations confer poor responses to VitB6 therapy. Hence, accrual of patients with an unexpectedly better response, which was observed in our case, may help elucidate the pathogenesis of and therapies for XLSA.

Efficacy of Denosumab for Osteoporosis in Three Female Patients with Osteogenesis Imperfecta.

Osteogenesis imperfecta (OI) is an inherited bone disorder that causes fractures due to impaired production of collagen type I. In recent years, denosumab, a human monoclonal antibody against receptor activator of nuclear factor κB ligand (RANKL), has become widely used as an anti-osteoclastic agent for osteoporosis. This study investigated osteoporotic cases of OI to examine effects of denosumab on bone fragility. This was a retrospective, consecutive case series that included 3 female patients aged 42, 40, and 14 years, respectively. One patient carries a point mutation (c.G769A) in the COL1A1 gene, encoding collagen type I alpha 1 chain, which causes an amino-acid substitution (p.G257R). By contrast, no mutation was found in the analyzed regions of the OI responsive genes in another two patients (mother and daughter). These three patients underwent subcutaneous injection of denosumab every 6 months. All patients underwent dual-energy X-ray absorptiometry for bone mineral density (BMD) measurement of the lumbar 1-4 spine (L-BMD) and bilateral hips (H-BMD) before and during treatment. BMD and laboratory data were evaluated before, between 2 and 4 months, and at 6, 12, 18, and 24 months of therapy. No fractures or severe side effects, such as hypocalcemia, were observed during denosumab treatment. Both L-BMD and H-BMD were increased by denosumab. At 24 months, the mean percentage changes in L-BMD and H-BMD were 14.7% and 15.1%, respectively. In conclusion, no bone fragility fractures occurred during 2 years of denosumab administration in OI patients. Denosumab therefore is a good therapeutic option in the OI patients.

Elevation of neuron specific enolase and brain iron deposition on susceptibility-weighted imaging as diagnostic clues for beta-propeller protein-associated neurodegeneration in early childhood: Additional case report and review of the literature.

Beta-propeller protein-associated neurodegeneration (BPAN), also known as static encephalopathy of childhood with neurodegeneration in adulthood (SENDA), is a subtype of neurodegeneration with brain iron accumulation (NBIA). BPAN is caused by mutations in an X-linked gene WDR45 that is involved in autophagy. BPAN is characterized by developmental delay or intellectual disability until adolescence or early adulthood, followed by severe dystonia, parkinsonism, and progressive dementia. Brain magnetic resonance imaging (MRI) shows iron deposition in the bilateral globus pallidus (GP) and substantia nigra (SN). Clinical manifestations and laboratory findings in early childhood are limited. We report a 3-year-old girl with BPAN who presented with severe developmental delay and characteristic facial features. In addition to chronic elevation of serum aspartate transaminase, lactate dehydrogenase, creatine kinase, and soluble interleukin-2 receptor, she had persistent elevation of neuron specific enolase (NSE) in serum and cerebrospinal fluid. MRI using susceptibility-weighted imaging (SWI) demonstrated iron accumulation in the GP and SN bilaterally. Targeted next-generation sequencing identified a de novo splice-site mutation, c.831-1G>C in WDR45, which resulted in aberrant splicing evidenced by reverse transcriptase-PCR. Persistent elevation of NSE and iron deposition on SWI may provide clues for diagnosis of BPAN in early childhood.

A MinION-based Long-Read Sequencing Application With One-Step PCR for the Genetic Diagnosis of 21-Hydroxylase Deficiency.

CONTEXT: Recently developed long-read sequencing (LRS) technology has been considered an option for CYP21A2 analysis. However, the clinical use of LRS for CYP21A2 analysis is limited. OBJECTIVE: This study's objective is to develop an efficient and low-cost LRS system for CYP21A2 screening. METHODS: A DNA fragment library was prepared in a single polymerase chain reaction (PCR) that covers the entire CYP21A2 gene and all known junctions caused by TNXB gene structural rearrangements, yielding a single 8-kb product of CYP21A2 or CYP21A1P/CYP21A2 chimera. After barcoding, the PCR products were sequenced on a MinION-based platform with Flongle Flow Cell R9.4.1 and R10.4.1. RESULTS: The reference genotypes of 55 patients with 21-hydroxylase deficiency (21OHD) were established using the conventional method with multiplex ligation-dependent probe amplification (MLPA) and nested PCR. LRS using Flongle Flow Cell R9.4.1 yielded consistent results. Additionally, the recently updated LRS "duplex" analysis with Flongle flow cell R10.4.1 was tested to reveal an advantage of accurately sequencing a variant located on the homopolymer region. By introducing a barcode system, the cost was reduced to be comparable to that of conventional analysis. A novel single-nucleotide variation was discovered at the acceptor site of intron 7, c.940-1G > C. We also identified a subtype of the classical chimeric junction CH2, "CH2a," in the region from the latter part of intron 5 to exon 6. CONCLUSION: We successfully established a novel low-cost and highly accurate LRS system for 21OHD genetic analysis. Our study provides insight into the feasibility of LRS for diagnosing 21OHD and other genetic diseases caused by structural rearrangements.

Racemization of the aspartic acid residue of amyloid-ß peptide by a radical reaction.

Human amyloid-ß peptide 1-42 (Aß) was subjected to a radical reaction by using ascorbic acid and CuCl(2). The percentage of D-aspartic acid (D-Asp) after 24 h had increased to 6.69 ± 0.09%, this being comparable with the reported D-Asp concentration of purified core amyloids in Alzheimer's disease patients. This racemization was significantly inhibited by radical scavengers. L-Alanine was also racemized during the same reaction.

Pathophysiological Investigation of Skeletal Deformities of Musculocontractural Ehlers-Danlos Syndrome Using Induced Pluripotent Stem Cells.

Musculocontractural Ehlers-Danlos syndrome caused by mutations in the carbohydrate sulfotransferase 14 gene (mcEDS-CHST14) is a heritable connective tissue disorder characterized by multiple congenital malformations and progressive connective tissue fragility-related manifestations in the cutaneous, skeletal, cardiovascular, visceral, and ocular systems. Progressive skeletal deformities are among the most frequent and serious complications affecting the quality of life and activities of daily living in patients. After establishing induced pluripotent stem cells (iPSCs) from cultured skin fibroblasts of three patients with mcEDS-CHST14, we generated a patient iPSC-based human osteogenesis model and performed an in vitro assessment of the phenotype and pathophysiology of skeletal deformities. Patient-derived iPSCs presented with remarkable downregulation of osteogenic-specific gene expression, less alizarin red staining, and reduced calcium deposition compared with wild-type iPSCs at each stage of osteogenic differentiation, including osteoprogenitor cells, osteoblasts, and osteocytes. These findings indicated that osteogenesis was impaired in mcEDS-CHST14 iPSCs. Moreover, the decrease in decorin (DCN) expression and increase in collagen (COL12A1) expression in patient-derived iPSCs elucidated the contribution of CHST14 dysfunction to skeletal deformities in mcEDS-CHST14. In conclusion, this disease-in-a-dish model provides new insight into the pathophysiology of EDS and may have the potential for personalized gene or drug therapy.

Severe Cerebral Small Vessel Disease Caused by the Uniallelic p.A252T Variant of HTRA1.

Objective: To investigate the clinical effect of a heterozygous missense variant of HTRA1 on cerebral small vessel disease (CSVD) in a large Japanese family with a p.A252T variant. Methods: We performed clinical, laboratory, radiologic, and genetic evaluations of members of a previously reported family with cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL). Results: Two family members were previously reported patients with CARASIL. Among 6 uniallelic p.A252T carriers, 2 had neurologic symptoms with brain MRI abnormalities, 2 showed CSVD on the MRI only, and the other 2 were unaffected. Clinical phenotypes of 2 heterozygous patients were comparable with those of patients with CARASIL, whereas the other 3 heterozygous patients had developed milder and later-onset CSVD. One heterozygous carrier was asymptomatic. Discussion: Previous studies have suggested that uniallelic p.A252T causes disease. However, our study revealed that patients with uniallelic p.A252T can have severe and young-onset CSVD. The clinical manifestations of uniallelic variant carriers were highly variable, even within the same family. Male and atherosclerotic risk factors were considered to be additional factors in the severity of neurologic symptoms in uniallelic p.A252T carriers, suggesting that strict control of vascular risk factors can prevent vascular events in uniallelic HTRA1 carriers.