De novo mutation in COL2A1 leads to lethal foetal skeletal dysplasia

COL9A1-related disorder with pectus carinatum, without epiphyseal dysplasia: case report and review of literature

COL9A1 encodes the alpha-1 chain of type IX collagen heterotrimer, which is a vital component of collagen fibrils in hyaline cartilage. There are preliminary lines of evidence suggesting that COL9A1 mutations may be associated with autosomal dominant multiple epiphyseal dysplasia (MED), a disorder affecting the epiphysis of long bones. With only 2 reported cases (both from the same family) of MED in autosomal dominant COL9A1-related disorders (MIM 614135) in the clinical scientific literature hitherto, the phenotype is poorly understood at present. Here, we report the clinical and imaging findings associated with a novel COL9A1 mutation in comparison to the previously reported cases. We studied a 22-year-old male, who presented with a chronic history of leg pain and laxity of the knee joint, in the context of a history of pectus carinatum requiring a chest brace, and tall stature (height = 186.9 cm) with bilateral piezogenic pedal papules. Gene panel testing and a radiographic skeletal survey were subsequently performed. Gene panel test showed a heterozygous pathogenic variant in the COL9A1 that is denoted as c.188del (p.Phe63Serfs*3) and is predicted to result in a loss-of-function. The patient's long bones all appeared slender on a radiograph, without apparent epiphyseal dysplasia. Our findings suggest that the phenotypic spectrum of COL9A1-related disorders may potentially include other skeletal anomalies (such as pectus carinatum and slender appearance of long bones) aside from epiphyseal dysplasia.

Chondrocalcin: Insights into its regulation and multi-function in cartilage and bone

Type Ⅱ collagen (COLⅡ) is the primary constituent of the cartilage matrix, specifically present in vitreous bodies, cartilage, bone, and other skeletal elements. Therefore, the normal expression of COLⅡ is crucial for the normal development, linear growth, mechanical properties, and self-repairing ability of cartilage. Chondrocalcin, the C-propeptide of type Ⅱ procollagen, is not only a marker of COLⅡ synthesis but also one of the most abundant polypeptides in cartilage. This work examines the pivotal role of chondrocalcin in the synthesis of COLⅡ, comprehensively examining its regulation and multi-functions in cartilage and bone related diseases. Our findings suggest that mutations in the chondrocalcin-encoding domain of COL2A1 affect cartilage and bone development in clinical conditions.

Clinical Features of Seven COL2A1 Variations in Chinese Children With Type II Collagen Disorders

AIM

Type II collagen, encoded by the collagen type II alpha 1 (COL2A1) gene, is crucial for the structure of cartilage. This study aims to improve our understanding of Spondyloepiphyseal Dysplasia Congenita (SEDC) caused by mutations in COL2A1. We also aim to evaluate the safety and efficacy of growth hormone (GH) therapy in two SEDC patients.

METHODS

We performed genetic analyses of seven paediatric patients from unrelated Chinese families. Two patients received GH therapy, and their growth trajectories were monitored over 3.5 and 3 years.

RESULTS

Genetic screening identified six missense mutations (Gly1110Ser, Gly1107Glu, Gly873Arg, Gly456Ala, Gly1062Ser and Gly1182Arg) and one intron variant in COL2A1. All patients (five girls and two boys, ranging from 2 years and 7 months to 12 years) were diagnosed with SEDC, exhibiting disproportionate short stature and skeletal abnormalities. GH therapy resulted in height increases of 0.76 and 0.27 standard deviation scores over 3.5 and 3 years, respectively, with no significant side effects.

CONCLUSION

This study expands the mutation spectrum of COL2A1 and supports the efficacy and safety of GH therapy in SEDC patients, highlighting the need for multi-center studies to further investigate GH's therapeutic potential.

Naturally occurring genetic diseases caused by de novo variants in domestic animals

With the advent of next-generation sequencing, an increasing number of cases of de novo variants in domestic animals have been reported in scientific literature primarily associated with clinically severe phenotypes. The emergence of new variants at each generation is a crucial aspect in understanding the pathology of early-onset diseases in animals and can provide valuable insights into similar diseases in humans. With the aim of collecting deleterious de novo variants in domestic animals, we searched the scientific literature and compiled reports on 42 de novo variants in 31 genes in domestic animals. No clear disease-associated phenotype has been established in humans for three of these genes (NUMB, ANKRD28 and KCNG1). For the remaining 28 genes, a strong similarity between animal and human phenotypes was recognized from available information in OMIM and OMIA, revealing the importance of comparative studies and supporting the use of domestic animals as natural models for human diseases, in line with the One Health approach.

vwa1 Knockout in Zebrafish Causes Abnormal Craniofacial Chondrogenesis by Regulating FGF Pathway

Hemifacial microsomia (HFM), a rare disorder of first- and second-pharyngeal arch development, has been linked to a point mutation in VWA1 (von Willebrand factor A domain containing 1), encoding the protein WARP in a five-generation pedigree. However, how the VWA1 mutation relates to the pathogenesis of HFM is largely unknown. Here, we sought to elucidate the effects of the VWA1 mutation at the molecular level by generating a vwa1-knockout zebrafish line using CRISPR/Cas9. Mutants and crispants showed cartilage dysmorphologies, including hypoplastic Meckel’s cartilage and palatoquadrate cartilage, malformed ceratohyal with widened angle, and deformed or absent ceratobranchial cartilages. Chondrocytes exhibited a smaller size and aspect ratio and were aligned irregularly. In situ hybridization and RT-qPCR showed a decrease in barx1 and col2a1a expression, indicating abnormal cranial neural crest cell (CNCC) condensation and differentiation. CNCC proliferation and survival were also impaired in the mutants. Expression of FGF pathway components, including fgf8a, fgfr1, fgfr2, fgfr3, fgfr4, and runx2a, was decreased, implying a role for VWA1 in regulating FGF signaling. Our results demonstrate that VWA1 is essential for zebrafish chondrogenesis through effects on condensation, differentiation, proliferation, and apoptosis of CNCCs, and likely impacts chondrogenesis through regulation of the FGF pathway.

Zebrafish Model of Stickler Syndrome Suggests a Role for Col2a1a in the Neural Crest during Early Eye Development

Most cases of Stickler syndrome are due to autosomal-dominant COL2A1 gene mutations leading to abnormal type II collagen. Ocular findings include axial eye lengthening with vitreal degeneration and early-onset glaucoma, which can result in vision loss. Although COL2A1 is a major player in cartilage and bone formation, its specific role in eye development remains elusive. We investigated the role of Col2a1a in neural crest migration and differentiation during early zebrafish eye development. In situ hybridization, immunofluorescence, live imaging, exogenous treatments [10 μM diethylaminobenzaldehyde (DEAB), 100 nM all-trans retinoic acid (RA) and 1-3% ethanol (ETOH)] and morpholino oligonucleotide (MO) injections were used to analyze wildtype Casper (roy-/-;nacre-/-), TgBAC(col2a1a::EGFP), Tg(sox10::EGFP) and Tg(foxd3::EGFP) embryos. Col2a1a colocalized with Foxd3- and Sox10-positive cells in the anterior segment and neural crest-derived jaw. Col2a1a expression was regulated by RA and inhibited by 3% ETOH. Furthermore, MO knockdown of Col2a1a delayed jaw formation and disrupted the ocular anterior segment neural crest migration of Sox10-positive cells. Interestingly, human COL2A1 protein rescued the MO effects. Altogether, these results suggest that Col2a1a is a downstream target of RA in the cranial neural crest and is required for both craniofacial and eye development.

Zebrafish Is a Powerful Tool for Precision Medicine Approaches to Neurological Disorders

Personalized medicine is currently one of the most promising tools which give hope to patients with no suitable or no available treatment. Patient-specific approaches are particularly needed for common diseases with a broad phenotypic spectrum as well as for rare and yet-undiagnosed disorders. In both cases, there is a need to understand the underlying mechanisms and how to counteract them. Even though, during recent years, we have been observing the blossom of novel therapeutic techniques, there is still a gap to fill between bench and bedside in a patient-specific fashion. In particular, the complexity of genotype-to-phenotype correlations in the context of neurological disorders has dampened the development of successful disease-modifying therapeutics. Animal modeling of human diseases is instrumental in the development of therapies. Currently, zebrafish has emerged as a powerful and convenient model organism for modeling and investigating various neurological disorders. This model has been broadly described as a valuable tool for understanding developmental processes and disease mechanisms, behavioral studies, toxicity, and drug screening. The translatability of findings obtained from zebrafish studies and the broad prospect of human disease modeling paves the way for developing tailored therapeutic strategies. In this review, we will discuss the predictive power of zebrafish in the discovery of novel, precise therapeutic approaches in neurosciences. We will shed light on the advantages and abilities of this in vivo model to develop tailored medicinal strategies. We will also investigate the newest accomplishments and current challenges in the field and future perspectives.