Identification of two novel COL10A1 heterozygous mutations in two Chinese pedigrees with Schmid-type metaphyseal chondrodysplasia

The p.W651fsX666 mutation on COL10A1 results in impaired trimerization of normal collagen X to induce Schmid type Metaphyseal chondrodysplasia

Haploinsufficiency resulting from the degradation of mutant Collagen Type X Alpha 1 Chain (COL10A1) mRNA by nonsense-mediated decay (NMD) has been attributed to the pathogenesis of Schmid-type metaphyseal chondrodysplasia (SMCD) in cases involving nonsense mutations. However, this mechanism does not fully explain the complexity of SMCD. In this study, we identified a c.1951_1952 InsT (p.W651 fsX666) mutation in exon 3 of COL10A1 that is associated with chondrodysplasia phenotypes in a two-generation family with SMCD. The mRNA decay of the mutant COL10A1 (named as affected E666X-COL10A1) is caused by the p.W651fsX666 mutation, which also disrupts the trimerization of normal collagen X. However, the mutant mRNA decay of affected exogenous E666X-COL10A1, as well as the complete degradation of E666X-COL10A1 mRNA in the proband, is not significantly induced by the W651fsX666 mutation. In vitro trimerization analyses results indicate that the trimerization of normal collagen X and wild-type collagen X are disrupted by W651fsX666 and E666X-collagen X mutations, respectively, suggesting that the mutant allele collagen X may impose a dominant-negative effect on the normal collagen X. Our results are the first to reveal that the impaired trimerization of normal collagen X is caused by the W651fsX666 mutation and a dominant-negative effect on the normal allele collagen X exerted by the mutant allele collagen X, causing impaired trimerization of collagen X, which will interpret the phenotype variability among the affected individuals in the pedigree with metaphyseal chondrodysplasia type Schmid (MCDS) studied.

Natural history and genetic spectrum of the Turkish metaphyseal dysplasia cohort, including rare types caused by biallelic COL10A1, COL2A1, and LBR variants

BACKGROUND

Metaphyseal chondrodysplasias are a heterogeneous group of diseases characterized by short and bowed long bones and metaphyseal abnormality. The aim of this study is to investigate the genetic etiology and prognostic findings in patients with metaphyseal dysplasia.

METHODS

Twenty-four Turkish patients were included in this study and 13 of them were followed for 2-21 years. COL10A1, RMRP sequencing and whole exome sequencing were performed.

RESULTS

Results: Seven heterozygous pathogenic variants in COL10A1 were detected in 17 patients with Schmid type metaphyseal chondrodysplasia(MCDS). The phenotype was more severe in patients with heterozygous missense variants (one in signal peptide domain at the N-terminus of the protein, the other, class-1 group mutation at NC1 domain) compared to the patients with truncating variants. Short stature and coxa vara deformity appeared after 3 and 5 years of age, respectively, while large femoral head resolved after the age of 13 years in MCDS group. Interestingly, one patient with severe phenotype also had a biallelic missense variant in NC1 domain of COL10A1. Three patients with biallelic mutations in RMRP had prenatal onset short stature with short limb, and typical findings of cartilage hair hypoplasia (CHH). While immunodeficiency or recurrent infections were not observed, resistant congenital anemia was detected in one. Biallelic mutation in LBR was described in a patient with prenatal onset short stature, short and curved limb and metaphyseal abnormalities. Unlike previously reported patients, this patient had ectodermal findings, similar to CHH. A biallelic COL2A1 mutation was also found in the patient with lower limb deformities and metaphyseal involvement without vertebral and epiphyseal changes.

CONCLUSION

Long-term clinical characteristics are presented in a metaphyseal dysplasia cohort, including rare types caused by biallelic COL10A1, COL2A1, and LBR variants. We also point out that the domains where mutations on COL10A1 take place are important in the genotype-phenotype relationship.

A detailed understanding of the COL10A1 and SOX9 genes interaction based on potentially damaging mutations in gastric cancer using computational techniques

Gastric cancer (GC) has limited effective treatment options and is followed up with biomarkers that have insufficient sensitivity and specificity. Recent studies on Collagen Type X Alpha 1 Chain (COL10A1) show that the COL10A1 gene may be a diagnostic and/or prognostic biomarker for different cancer types. Moreover, its relationship with the Sex determining Region Y (SRY)-related High-Mobility Group (HMG) box (SOX9) gene which is also a transcription factor, was discovered recently, and co-expression of these two genes are associated with the development of GC. However, to the best of our knowledge, there is no study in the literature on how potential damaging mutations in the SOX9 and COL10A1 genes can affect their interactions. The aim of this study is to investigate the interactions of wild-type and potentially damaging mutated structures of COL10A1 and SOX9 genes. Thus, outputs for drug development and therapeutic strategies for GC can be obtained. For this purpose, structure validation and energy minimization analyses as well as docking and binding affinity calculations were performed. As a result, it was found that all investigated mutations (P563S, I588L, T624A, H165R and N110T) increased the binding affinity between the COL10A1-SOX9 complex, especially the N110T and H165R mutants in SOX9. As a conclusion, the N110T and H165R mutants in SOX9 may contribute to tumor progression. Therefore, it is important to consider these mutations for future therapeutic strategies.Communicated by Ramaswamy H. Sarma.

Clinical Characteristics of Short-Stature Patients With Collagen Gene Mutation and the Therapeutic Response to rhGH

CONTEXT

Clinical genetic evaluation has been demonstrated as an important tool to elucidate the causes of growth disorders. Genetic defects of collagen formation (the collagenopathies) have been reported to be associated with short stature and skeletal dysplasias. Etiological diagnosis of skeletal abnormality-related short stature is challenging, and less is known about recombinant human growth hormone (rhGH) therapy.

OBJECTIVE

This is a single-center cohort study which aims at exploring the genetic architecture of short-stature children with skeletal abnormalities and evaluating the frequency of collagenopathies to determine their phenotype, including the rhGH treatment response.

PATIENTS AND METHODS

One hundred and six children with short stature and skeletal abnormalities were enrolled who were evaluated by next-generation sequencing (NGS) to detect variants in the skeletal collagen genes including COL1A1, COL1A2, COL2A1, COL9A1, COL9A2, COL9A3, COL10A1, COL11A1, and COL11A2. The results were evaluated using American College of Medical Genetics and Genomics (ACMG) guidelines. Clinical characteristics and rhGH treatment response were summarized.

RESULTS

Twenty-four pathogenic or likely pathogenic variants of collagen genes were found in 26 of 106 (24.5%) short-stature patients with skeletal abnormalities, of which COL2A1 mutations were the most common, accounting for about 57.7%. Other frequent mutations associated with skeletal development include FGFR3, ACAN, NPR2, COMP, and FBN1 in 12.2%, 0.9%, 0.8%, 0.4%, and 0.4%, respectively, resulting in significantly different degrees of short stature. An overview of clinical features of collagenopathies showed growth retardation, skeletal abnormalities, and heterogeneous syndromic abnormalities involving facial, eye, hearing, and cardiac abnormalities. The average height of 9 patients who received rhGH treatment improved from a median of -3.2 ± 0.9 SDS to -2.2 ± 1.3 SDS after 2.8 ± 2.1 years. The most significant height improvement of 2.3 SDS and 1.7 SDS was also seen in two patients who had been treated for more than 6 years.

CONCLUSIONS

A proband-based NGS revealed that distinct genetic architecture underlies short stature in varying degrees and clinical features. Skeletal abnormality-related short stature involving multiple systems should be tested for skeletal collagen gene mutation. Limited rhGH treatment data indicate an improved growth rate and height, and close monitoring of adverse reactions such as scoliosis is required.

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

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.

Short and sweet: foreleg abnormalities in Havanese and the role of the FGF4 retrogene

Background

Cases of foreleg deformities, characterized by varying degrees of shortened and bowed forelegs, have been reported in the Havanese breed. Because the health and welfare implications are severe in some of the affected dogs, further efforts should be made to investigate the genetic background of the trait.

A FGF4-retrogene on CFA18 is known to cause chondrodystrophy in dogs. In most breeds, either the wild type allele or the mutant allele is fixed. However, the large degree of genetic diversity reported in Havanese, could entail that both the wild type and the mutant allele segregate in this breed. We hypothesize that the shortened and bowed forelegs seen in some Havanese could be a consequence of FGF4RG-associated chondrodystrophy.

Here we study the population prevalence of the wild type and mutant allele, as well as effect on phenotype. We also investigate how the prevalence of the allele associated with chondrodystrophy have changed over time. We hypothesize that recent selection, may have led to a gradual decline in the population frequency of the lower-risk, wild type allele.

Results

We studied the FGF4-retrogene on CFA18 in 355 Havanese and found variation in the presence/absence of the retrogene. The prevalence of the non-chondrodystrophic wild type is low, with allele frequencies of 0.025 and 0.975 for the wild type and mutant allele, respectively (linked marker).

We found that carriers of the beneficial wild type allele were significantly taller at the shoulder than mutant allele homozygotes, with average heights of 31.3 cm and 26.4 cm, respectively.

We further found that wild type carriers were born on average 4.7 years earlier than mutant allele homozygotes and that there has been a gradual decline in the population frequency of the wild type allele during the past two decades.

Conclusions

Our results indicate that FGF4RG-associated chondrodystrophy may contribute to the shortened forelegs found in some Havanese and that both the wild type and mutant allele segregate in the breed. The population frequency of the wild type allele is low and appear to be decreasing. Efforts should be made to preserve the healthier wild type in the population, increase the prevalence of a more moderate phenotype and possibly reduce the risk of foreleg pathology.