A non-disruptive and efficient knock-in approach allows fate tracing of resident osteoblast progenitors during repair of vertebral lesions in medaka.

During bone development and repair, osteoblasts are recruited to bone deposition sites. To identify the origin of recruited osteoblasts, cell lineage tracing using Cre/loxP recombination is commonly used. However, a confounding factor is the use of transgenic Cre drivers that do not accurately recapitulate endogenous gene expression or the use of knock-in Cre drivers that alter endogenous protein activity or levels. Here, we describe a CRISPR/Cas9 homology-directed repair knock-in approach that allows efficient generation of Cre drivers controlled by the endogenous gene promoter. In addition, a self-cleaving peptide preserves the reading frame of the endogenous protein. Using this approach, we generated col10a1p2a-CreERT2 knock-in medaka and show that tamoxifen-inducible CreERT2 efficiently recombined loxP sites in col10a1 cells. Similar knock-in efficiencies were obtained when two unrelated loci (osr1 and col2a1a) were targeted. Using live imaging, we traced the fate of col10a1 osteoblast progenitors during bone lesion repair in the medaka vertebral column. We show that col10a1 cells at neural arches represent a mobilizable cellular source for bone repair. Together, our study describes a previously unreported strategy for precise cell lineage tracing via efficient and non-disruptive knock-in of Cre.

The CHARGE syndrome ortholog CHD-7 regulates TGF-ß pathways in Caenorhabditis elegans.

CHARGE syndrome is a complex developmental disorder caused by mutations in the chromodomain helicase DNA-binding protein-7 (CHD7) and characterized by retarded growth and malformations in the heart and nervous system. Despite the public health relevance of this disorder, relevant cellular pathways and targets of CHD7 that relate to disease pathology are still poorly understood. Here we report that chd-7, the nematode ortholog of Chd7, is required for dauer morphogenesis, lifespan determination, stress response, and body size determination. Consistent with our discoveries, we found chd-7 to be allelic to scd-3, a previously identified dauer suppressor from the DAF-7/ tumor growth factor-ß (TGF-ß) pathway. Epistatic analysis places CHD-7 at the level of the DAF-3/DAF-5 complex, but we found that CHD-7 also directly impacts the expression of multiple components of this pathway. Transcriptomic analysis revealed that chd-7 mutants fail to repress daf-9 for execution of the dauer program. In addition, CHD-7 regulates the DBL-1/BMP pathway components and shares roles in male tail development and cuticle synthesis. To explore a potential conserved function for chd-7 in vertebrates, we used Xenopus laevis embryos, an established model to study craniofacial development. Morpholino-mediated knockdown of Chd7 led to a reduction in col2a1 messenger RNA (mRNA) levels, a collagen whose expression depends on TGF-ß signaling. Both embryonic lethality and craniofacial defects in Chd7-depleted tadpoles were partially rescued by overexpression of col2a1 mRNA. We suggest that Chd7 has conserved roles in regulation of the TGF-ß signaling pathway and pathogenic Chd7 could lead to a defective extracellular matrix deposition.

PLCγ1 deficiency in chondrocytes accelerates the age-related changes in articular cartilage and subchondral bone.

Ageing is the most prominent risk for osteoarthritis (OA) development. This study aimed to investigate the role of phosphoinositide-specific phospholipase Cγ (PLCγ) 1, previously linked to OA progression, in regulating age-related changes in articular cartilage and subchondral bone. d-galactose (d-Gal) was employed to treat chondrocytes from rats and mice or injected intraperitoneally into C57BL/6 mice. RTCA, qPCR, Western blot and immunohistochemistry assays were used to evaluate cell proliferation, matrix synthesis, senescence genes and senescence-associated secretory phenotype, along with PLCγ1 expression. Subchondral bone morphology was assessed through micro-CT. In mice with chondrocyte-specific Plcg1 deficiency (Plcg1flox/flox; Col2a1-CreERT), articular cartilage and subchondral bone were examined over different survival periods. Our results showed that d-Gal induced chondrocyte senescence, expedited articular cartilage ageing and caused subchondral bone abnormalities. In d-Gal-induced chondrocytes, diminished PLCγ1 expression was observed, and its further inhibition by U73122 exacerbated chondrocyte senescence. Plcg1flox/flox; Col2a1-CreERT mice exhibited more pronounced age-related changes in articular cartilage and subchondral bone compared to Plcg1flox/flox mice. Therefore, not only does d-Gal induce senescence in chondrocytes and age-related changes in articular cartilage and subchondral bone, as well as diminished PLCγ1 expression, but PLCγ1 deficiency in chondrocytes may also accelerate age-related changes in articular cartilage and subchondral bone. PLCγ1 may be a promising therapeutic target for mitigating age-related changes in joint tissue.

No correlation to collagen synthesis disorders in patients with Perthes' disease: a nationwide Swedish register study of 3488 patients.

BACKGROUND: Mutations of the COL2A1 gene have been identified in patients with Perthes' disease. Several studies have hypothesised a connection between Perthes' disease and collagen synthesis disorders, especially COL2A1-related disorders, but no large studies on the subject have been made. The aim of this study was thus to discover if there is a connection between patients presenting with Perthes' disease, and collagen synthesis disorders. A secondary aim was to see if the children with both disorders had less optimal birth characteristics than the rest. METHODS: Swedish national registers were used to collect data on children diagnosed with Perthes' disease or a collagen synthesis disorder. These registers include all births in Sweden, and data from both outpatient and in-hospital visits. A wide range of data is included besides diagnoses. All children with follow-up data to the age of 15 years were included. Pearson's chi-square was used for analysis. Statistical significance was further analysed with Fisher's Exact Test. RESULTS: In total, 3488 children with either diagnosis were included. 1620 children had only Perthes disease, while 1808 children had only a collagen synthesis disorder. Five children were found to have both the diagnosis Perthes' disease and a collagen synthesis disorder. One child was large for their gestational age and none of the children had a low birthweight. Two of the children were moderately preterm. CONCLUSIONS: The distinct lack of overlap in such a large body of material raises doubt about a connection between the presentation of Perthes' disease and collagen synthesis disorders, either COL2A1-related or not. We could not find an overrepresentation of less optimal birth characteristics either.

Localised Collagen2a1 secretion supports lymphatic endothelial cell migration in the zebrafish embryo.

The lymphatic vasculature develops primarily from pre-existing veins. A pool of lymphatic endothelial cells (LECs) first sprouts from cardinal veins followed by migration and proliferation to colonise embryonic tissues. Although much is known about the molecular regulation of LEC fate and sprouting during early lymphangiogenesis, we know far less about the instructive and permissive signals that support LEC migration through the embryo. Using a forward genetic screen, we identified mbtps1 and sec23a, components of the COP-II protein secretory pathway, as essential for developmental lymphangiogenesis. In both mutants, LECs initially depart the cardinal vein but then fail in their ongoing migration. A key cargo that failed to be secreted in both mutants was a type II collagen (Col2a1). Col2a1 is normally secreted by notochord sheath cells, alongside which LECs migrate. col2a1a mutants displayed defects in the migratory behaviour of LECs and failed lymphangiogenesis. These studies thus identify Col2a1 as a key cargo secreted by notochord sheath cells and required for the migration of LECs. These findings combine with our current understanding to suggest that successive cell-to-cell and cell-matrix interactions regulate the migration of LECs through the embryonic environment during development.

Co-occurrence of Spondyloepiphyseal Dysplasia and X-Linked Hypophosphatemia in a Three-Generation Chinese Family.

Rare genetic skeletal disorders (GSDs) remain the major problem in orthopedics and result in significant morbidity in patients, but the causes are highly diverse. Precise molecular diagnosis will benefit management and genetic counseling. This study aims to share the diagnostic experience on a three-generation Chinese family with co-occurrence of spondyloepiphyseal dysplasia (SED) and X-linked hypophosphatemia (XLH), and evaluate the therapeutic effects of two third-generation siblings. The proband, his younger brother, and mother presented with short stature, skeletal problems, and hypophosphatemia. His father, paternal grandfather, and aunt also manifested short stature and skeletal deformities. Whole exome sequencing (WES) of proband-brother-parents initially only found the proband and his younger brother had a pathogenic c.2833G > A(p.G945S) variant in the COL2A1 gene inherited from their father. Re-analysis of WES uncovered the proband and his younger brother also harbored a pathogenic ex.12 del variant in the PHEX gene transmitted from their mother. Sanger sequencing, agarose gel electrophoresis, and quantitative polymerase chain reaction proved these results. The proband and his younger brother were confirmed to have a paternally inherited SED and a maternally inherited XLH. During a 2.8-year follow-up, these two siblings remained short stature and hypophosphatemia, but their radiographic signs and serum bone alkaline phosphatase levels were improved with treatment of oral phosphate and calcitriol. Our study presents the first report of co-occurrence of SED and XLH, shows the possibility that two different rare GSDs co-exist in a single patient, and alerts clinicians and geneticists to be cautious about this condition. Our study also suggests that next-generation sequencing has limit in detecting exon-level large deletions.

Long-term anatomical and functional outcomes of surgical treatment of retinal complications in children and adolescents with Stickler syndrome between 2004 and 2021.

BACKGROUND: Stickler syndrome (STL) is an inherited progressive connective tissue collagen disorder. STL is the most common hereditary cause of retinal complications, retinal tears, and the development of retinal detachment (RD) in childhood. The aim of the study was to evaluate the long-term anatomical and functional results of surgical treatment of retinal complications in children and adolescents affected by STL. METHODS: A retrospective, single-center study was performed a cohort of children with STL who underwent retinal surgery between 2004 and 2021. RESULTS: The study group consisted of nine children; the mean age at the time of the retinal tear with/without retinal detachment was 7.2 (2-10) years, and the mean follow-up period was 9.6 (5-16) years. Pathogenic variants COL2A1 (5 children) and COL11A1 (3 children) were confirmed in our cohort. In total, we operated on 13 eyes, 11 eyes with complicated RD and two eyes with multiple retinal defects, but without RD. At the end of the follow-up period, an attached retina was achieved 77% (10 eyes) with or without silicone oil tamponade: cryopexy alone was successful in one eye (10%), scleral buckling (EB) in five eyes (50%), and vitrectomy with silicone oil tamponade combined with EB in four eyes (40%). The mean number of surgeries was 2.3 per eye. The resulting best corrected visual acuity ranged from 0.03 to 0.1 in one eye, from 0.16 to 0.4 in two eyes, and from 0.5 to 1.0 in 7 eyes. CONCLUSION: Repair of retinal tears with/without retinal detachment in patients with Stickler syndrome often requires multiple surgeries with combinations of cryopexy, scleral buckling, and/or vitrectomy with silicone oil tamponade. Treatment of the ocular complications arising from STL requires long-term comprehensive care.

Czech dysplasia mimicking rheumatoid arthritis: Case series and literature review.

OBJECTIVE: This study reported a family with most members affected by Czech dysplasia. We examined the patients' clinical, laboratory, and imaging characteristics and evaluated their functional capacity using the Stanford Health Assessment Questionnaire-Disability Index. METHODS: The method used was case series description and literature review. RESULTS: This study showed that the pathogenic variant c.823C>T in the COL2A1 gene, which is a characteristic of Czech dysplasia, was found in 12 Brazilian individuals. Half of the patients in this family met the criteria for rheumatoid arthritis (RA) based on the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria. Patients had arthritis in their hand joints, synovitis detected by ultrasound, and alterations in inflammatory tests. The Stanford Health Assessment Questionnaire-Disability Index assessment revealed that all patients exhibited moderate-to-severe functional disability. What distinguish Czech dysplasia from RA are an autosomal dominant inheritance pattern, platyspondyly, sensorineural hearing loss, and shortening of the metatarsal bones. CONCLUSIONS: It is important to consider Czech dysplasia as a potential differential diagnosis for RA. This autosomal dominant skeletal dysplasia is associated with normal height, short metatarsals, platyspondyly, hearing loss, enlarged epiphyses, and precocious osteoarthritis. Inflammatory findings such as arthritis, synovitis, and alteration of inflammatory markers may also be present in individuals with Czech dysplasia.

A Novel missense mutation of COL2A1 gene in a large family with stickler syndrome type I.

Stickler syndrome type I (STL1, MIM 108300) is characterized by ocular, auditory, skeletal and orofacial manifestations. Nonsyndromic ocular STL1 (MIM 609508) characterized by predominantly ocular features is a subgroup of STL1, and it is inherited in an autosomal dominant manner. In this study, a novel variant c.T100>C (p.Cys34Arg) in COL2A1 related to a large nonsyndromic ocular STL1 family was identified through Exome sequencing (ES). Bioinformatics analysis indicated that the variant site was highly conserved and the pathogenic mechanism of this variant may involve in affected structure of chordin-like cysteine-rich (CR) repeats of ColIIA. Minigene assay indicated that this variant did not change alternative splicing of exon2 of COL2A1. Moreover, the nonsyndromic ocular STL1 family with 16 affected members showed phenotype variability and certain male gender trend. None of the family members had hearing loss. Our findings would expand the knowledge of the COL2A1 mutation spectrum, and phenotype variability associated with nonsyndromic ocular STL1. Search for genetic modifiers and related molecular pathways leading to the phenotype variation warrants further studies.

Low-intensity photobiomodulation at 632.8 nm increases tgfß3, col2a1, and sox9 gene expression in rat bone marrow mesenchymal stem cells in vitro.

The high incidence of cartilage destructions, as well as the social and economic importance of this pathology attracted great interest to the problem. At the present time, some data are available about the 632.8 nm low-intensity laser photobiomodulation positive effect on the cartilage tissue proliferation. The effect of this wavelength laser irradiation on the mesenchimal stem cell (MSC) differentiation in the chondrogenic direction was studied. The main aim of this work was to assess the low-intensity photobiomodulation effect on chondrogenesis. In this experiment, the cell model was used to compare the photobiomodulation and cytokine Tgfß3 (transforming growth factor ß 3) effects. Bone marrow MSCs were isolated from Wistar rats and cultured for the third passage. Chondrogenic effects of low-intensity He-Ne laser photobiomodulation and cytokine Tgfß3 (10 ng/µL) were analyzed and compared after 21 days. The radiation source was the standard LGN-208 helium-neon (He-Ne) laser (632.8 nm, 1.7 mWt). Irradiation was performed cyclically for 15 min with 45-min pauses. The increase of the responsible for chondrogenesis (col2a1, tgfß3, and sox9) main gene expression under the photobiomodulation at 632.8 nm was evaluated in comparison with Tgfß3 effect. The tgfß3, col2a1, and sox9 gene expression increase was obtained in two experimental groups: using the laser photobiomodulation and cytokine Tgfß3 effect. Gene expression levels of tgfß3, col2a1, and sox9 were measured using real-time polymerase chain reaction (RT-PCR) according to the -ΔΔCt method. It was found that the responsible for chondrogenesis genes expression (tgfß3, col2a1, sox9) increased under the action of specific laser photobiomodulation during the observation period (from 0 to 21 days). The chondrogenic differentiation effect under the laser irradiation is less significant than Tgfß3 cytokine effect.

Hearing Outcomes in Stickler Syndrome: Variation Due to COL2A1 and COL11A1.

OBJECTIVES: Stickler syndrome (SS) is a heterogeneous inherited connective tissue disorder, often due to a mutation in COL2A1 or COL11A1. Mutations in these genes cause collagen abnormalities affecting ocular, auditory, orofacial, and skeletal systems, including hearing loss, micrognathia, and cleft palate. Understanding the variability of hearing phenotypes based on genetic mutation has a significant impact on treatment and long-term care. DESIGN: A retrospective chart review of pediatric patients with a confirmed diagnosis of SS between January 2003 and December 2018 at a tertiary pediatric hospital was performed. Patients were excluded if they did not have genetic evaluation, craniofacial/ear, nose, and throat evaluation, and/or audiologic testing. Charts were reviewed for the following information: age, race, sex, SS diagnosis, genetic variant of SS, and audiological testing data. RESULTS: There were 29 confirmed patients with SS who met criteria, 16 with type I (COL2A1) and 13 with type II (COL11A1). Of the 13 patients with type II, 12 (92%) demonstrated hearing loss, ranging in severity from mild to severe. In type I, 25% of patients had mild or resolved hearing loss. CONCLUSION: Results suggest that patients with type II SS are more likely to have congenital hearing loss than type I. Data also suggest that the COL11A1 mutation shows consistently more severe hearing loss than the COL2A1 mutation.

Complex Phenotypic Presentation of Syndromic Hearing Loss Deciphered as Three Separate Clinical Entities: How Genetic Testing Guides Final Diagnosis.

BACKGROUND: Genetically determined prelingual hearing loss (HL) may occur in an isolated or syndromic form. OBJECTIVE: The aim of the study was to unravel the genetic cause of medical problems in a 21-year-old woman, whose phenotypic presentation extended beyond Stickler syndrome and included enlarged vestibular aqueduct (EVA) and persistent microhematuria. METHODS AND RESULTS: After sequencing of clinical exome, a known de novo COL2A1 pathogenic variant (c.1833+1G>A, p.?) causative for Stickler syndrome and one paternally inherited pathogenic change in COL4A5 (c.1871G>A, p.Gly624Asp) causative for X-linked Alport syndrome were found. No pathogenic variants, including those within the SLC26A4 5' region (Caucasian EVA haplotype), explaining the development of EVA, were identified. CONCLUSIONS: The study reveals a multilocus genomic variation in one individual and provides a molecular diagnosis of two HL syndromes that co-occur in the proband independent of each other. For the third entity, EVA, no etiological factor was identified. Our data emphasize the relevance of detailed clinical phenotyping for accurate genotype interpretation. Focus on broadening the phenotypic spectrum of known genetic syndromes may actually obscure patients with multiple molecular diagnoses.

A novel COL2A1 mutation causing spondyloepiphyseal dysplasia congenita in a Chinese family.

BACKGROUND: Spondyloepiphyseal dysplasia congenita is an autosomal dominant cartilaginous dysplasia characterized by short trunk, abnormal epiphysis, and flattened vertebral body. Skeletal features of SEDC are present at birth and evolve over time. Other features of SEDC include myopia and/or retinal degeneration with retinal detachment and cleft palate. A mutation in the COL2A1 gene located in 12q13.11 is considered as one of the important causes of SEDC. In 2016, Barat-Houari et al. reported a large number of COL2A1 mutations. Among them, a non-synonymous mutation in COL2A1 exon 37, c.2437G>A (p. Gly813Arg), has been reported to cause SEDC in only one patient from France so far. METHODS: We followed up a patient with SEDC phenotype and his family members. The clinical manifestations, physical examination and imaging examination, including X-ray, CT and MRI, were recorded. The whole-exome sequencing was used to detect the patients' genes, and the pathogenic genes were screened out by comparing with many databases. RESULTS: We report a Chinese patient with SEDC phenotype characterized by short trunk, abnormal epiphysis, flattened vertebral body, narrow intervertebral space, dysplasia of the odontoid process, chicken chest, scoliosis, hip and knee dysplasia, and joint hypertrophy. Gene sequencing analysis showed that the patient had a heterozygous mutation (c.2437G>A; p. Gly813Arg) in the COL2A1 gene. No COL2A1 mutation or SEDC phenotype was observed in his family members. This is the first report of SEDC caused by this mutation in an East Asian family. CONCLUSION: This report provides typical clinical, imaging, and genetic evidence for SEDC, confirming that a de novo mutation in the COL2A1 gene, c.2437G>A (p. Gly813Arg), causes SEDC in Chinese population.

Auditory dysfunction in type 2 Stickler Syndrome.

PURPOSE: To present the extent and site of lesion of auditory dysfunction in a large cohort of individuals with type 2 Stickler Syndrome. Type 2 Stickler Syndrome results from a mutation in the gene coding for α-1 type XI pro-collagen, which has been identified in the human vitreous, cartilage and the cochlea of the mouse. The condition is characterised by classic ocular abnormalities, auditory dysfunction, osteoarthropathy and oro-facial dysplasia. METHODS: This is a population study which used a combination of audiometric, tympanometric, and self-report measures on a series of 65 individuals (mean age 29.2 years, range 3-70, female 63.1%) with genetically confirmed type 2 Stickler Syndrome. RESULTS: Hearing impairment was identified in at least one ear for 69% of individuals. Analysis against age-matched normative data showed that reduced hearing sensitivity was present across all test frequencies. Sensorineural hearing loss was most common (77% of ears), with conductive (3%), mixed (7%) and no hearing loss (13%), respectively. The proportion of hypermobile tympanic membranes (24%) was less than previously documented in type 1 Stickler Syndrome. When present, this appears to arise as a direct result of collagen abnormalities in the middle ear. Self-report measures of speech and spatial hearing in sound were comparable to a non-syndromic cohort with similar audiometric thresholds. CONCLUSIONS: Auditory impairment in type 2 Stickler Syndrome is predominantly associated with cochlear hearing loss of varying severities across affected individuals. The impact on hearing thresholds can be seen across the frequency range, suggesting a contribution of defective collagen throughout the cochlea. Self-report questionnaires showed that difficulties understanding speech, and spatial information in sound (such as that used for localisation), were worse than a young, normal-hearing population but comparable to a non-syndromic cohort with similar audiometric thresholds. Therefore, it is likely that hearing loss in type 2 Stickler Syndrome arises in the auditory periphery, without significant central processing deficits.

Expanding the phenotype spectrum associated with pathogenic variants in the COL2A1 and COL11A1 genes.

We report the clinical findings of 26 individuals from 16 unrelated families carrying variants in the COL2A1 or COL11A1 genes. Using Sanger and next-generation sequencing, 11 different COL2A1 variants (seven novel), were identified in 13 families (19 affected individuals), all diagnosed with Stickler syndrome (STL) type 1. In nine families, the COL2A1 disease-causing variant arose de novo. Phenotypically, we observed myopia (95%) and retinal detachment (47%), joint hyperflexibility (92%), midface retrusion (84%), cleft palate (53%), and various degrees of hearing impairment (50%). One patient had a splenic artery aneurysm. One affected individual carrying pathogenic variant in COL2A1 showed no ocular signs including no evidence of membranous vitreous anomaly. In three families (seven affected individuals), three novel COL11A1 variants were found. The propositus with a de novo variant showed an ultrarare Marshall/STL overlap. In the second family, the only common clinical sign was postlingual progressive sensorineural hearing impairment (DFNA37). Affected individuals from the third family had typical STL2 signs. The spectrum of disease phenotypes associated with COL2A1 or COL11A1 variants continues to expand and includes typical STL and various bone dysplasias, but also nonsyndromic hearing impairment, isolated myopia with or without retinal detachment, and STL phenotype without clinically detectable ocular pathology.

Mutation Spectrum of Stickler Syndrome Type I and Genotype-phenotype Analysis in East Asian Population: a systematic review.

BACKGROUND: Stickler syndrome is the most common genetic cause of rhegmatogenous retinal detachment (RRD) in children, and has a high risk of blindness. Type I (STL1) is the most common subtype, caused by COL2A1 mutations. This study aims to analyze the mutation spectrum of COL2A1 and further elucidate the genotype-phenotype relationships in the East Asian populations with STL1, which is poorly studied at present. METHODS: By searching MEDLINE, Web of Science, CNKI, Wanfang Data, HGMD and Clinvar, all publications associated with STL1 were collected. Then, they were carefully screened to obtain all reported STL1-related variants in COL2A1 and clinical features in East Asian patients with STL1. RESULTS: There were 274 COL2A1 variants identified in 999 patients with STL1 from 466 unrelated families, and more than half of them were truncation mutations. Of the 107 STL1 patients reported in the East Asian population, it was found that patients with truncation mutations had milder systemic phenotypes, whereas patients with splicing mutations had severer phenotypes. In addition, several recurrent variants (c.3106C > T, c.1833 + 1G > A, c.2710C > T and c.1693C > T) were found. CONCLUSIONS: Genotype-phenotype correlations should certainly be studied carefully, contributed to making personalized follow-up plans and predicting prognosis of this disorder. Genome editing holds great potential for treating inherited diseases caused by pathogenic mutations. In this study, several recurrent variants were found, providing potential candidate targets for genetic manipulation in the future.

Integrated analysis of COL2A1 variant data and classification of type II collagenopathies.

The COL2A1 gene encodes the alpha-1 chain of type II procollagen. Type II collagen, comprised of three identical alpha-1 chains, is the major component of cartilage. COL2A1 gene variants are the etiologies of genetic diseases, termed type II collagenopathies, with a wide spectrum of clinical presentations. To date, at least 460 distinct COL2A1 mutations, identified in 663 independent probands, and 21 definite disorders have been reported. Nevertheless, a well-defined genotype-phenotype correlation has not been established, and few hot spots of mutation have been reported. In this study, we analyzed data of COL2A1 variants and clinical information of patients obtained from the Leiden Open Variation Database 3.0, as well as the currently available relevant literature. We determined the characteristics of the COL2A1 variants and distributions of the clinical manifestations in patients, and identified four likely genotype-phenotype correlations. Moreover, we classified 21 COL2A1-related disorders into five categories, which may assist clinicians in understanding the essence of these complex phenotypes and prompt genetic screening in clinical practice.

COL2A1 protective variant reduces sporadic rhegmatogenous retinal detachment severity.

Rhegmatogenous retinal detachment (RRD) is the most common type of RD, the separation of neurosensory retina from the underlying retinal pigment epithelium. The RRD patients can be benefited from appropriate treatment if detected early, especially for the people predicted at high risk. In this study, we aimed to investigate the genetic association and clinical correlation of collagen type II alpha 1 (COL2A1) variants with sporadic RRD in a southern Chinese population. Totally 156 RRD patients and 254 control subjects were recruited, and 12 COL2A1 tag single nucleotide polymorphisms were genotyped by the TaqMan assay. The RRD patients had poorer visual acuity (P < 0.001) and lower intraocular pressure (IOP; P < 0.001) in their surgical eyes compared to the fellow eyes. The COL2A1 rs1793958 variant was significantly associated with RRD in the genotypic (P = 0.024), allelic (P = 0.011, odds ratio (OR) = 0.669), recessive (P = 0.011, OR = 0.384) and homozygous models (P = 0.007, OR = 0.348). RRD patients carrying the rs1793958 G allele had smaller retinal detachment area (P = 0.041) and smaller IOP differences (P = 0.046) between the surgical and fellow eyes compared to those carrying the wildtype AA genotype. In summary, this study revealed that the COL2A1 rs1793958 variant is associated with reduced risk of sporadic RRD, and patients carrying rs1793958 G allele have lower RRD severity.

Spondyloepiphyseal dysplasia type Stanescu: Expanding the clinical and molecular spectrum of a very rare type II collagenopathy.

Spondyloepiphyseal dysplasia type Stanescu (SED-S) is a very rare type II collagenopathy. We describe an 8-year-old boy who presented with short trunk, C2-C3 vertebral fusion, hand, foot, leg and thigh pain, stiffness and limited joint mobility, and waddling gait. Radiographs showed platyspondyly with anterior wedging and endplate irregularities, broad femoral necks, and large epiphyses and epiphyseal equivalents. Differential diagnosis included progressive pseudorheumatoid dysplasia and SED-S. A skeletal dysplasia custom-designed NGS panel was performed and the heterozygous pathogenic variant c.620G>A; p.(Gly207Glu) in COL2A1 was detected, establishing the diagnosis of SED-S. Vertebral fusions, observed in our patient, have not been previously described in this dysplasia. This variant has not been previously associated with SED-S, but was reported in two other families with spondyloepiphyseal dysplasia. Thus, this case expands the clinical and mutational spectrum of SED-S and demonstrates that SED-S significantly overlaps with other skeletal dysplasias.

miR-455-3p enhances chondrocytes apoptosis and inflammation by targeting COL2A1 in the in vitro osteoarthritis model.

Emerging evidence has shown that microRNAs are important regulators in osteoarthritis (OA). Here, we investigated the function role of miR-455-3p in the pathogenesis of OA and the underlying molecular mechanisms. We first established the in vitro OA model using IL-1ß treated human chondrocyte cell line CHON-001. Using quantitative real time PCR, we observed the expression of miR-455-3p expression was up-regulated in the OA cartilage tissues and IL-1ß-treated chondrocytes. A series of function assays, including CCK-8 assay, flow cytometry, and ELISA assay showed that miR-455-3p contributed to IL-1ß-induced apoptosis and inflammation. Moreover, COL2A1 was confirmed as a target of miR-455-3p by luciferase reporter assay. Furthermore, COL2A1 knockdown reversed the effects of miR-455-3p inhibition, and aggravated the effects of miR-455-3p overexpression on IL-1ß-induced OA-like phenomenon. Taken together, these results revealed that miR-455-3p/COL2A1 axis might provide a novel molecular target for the treatment of OA.