A novel missense COL9A3 variant in a pedigree with multiple lumbar disc herniation

Trp3 allele in COL9A3 gene has been widely studied in populations with intervertebral disc disease. We identified a novel pathogenic variant in COL9A3 gene in a pedigree with multiple lumbar disc herniation (LDH). The proband was a 14-year-old boy who developed LDH at the L4/5 and L5/S1 spinal segments. His father, paternal aunt and grandfather were diagnosed with LDH at an age of 35, 30 and 23, respectively. By applying whole exome sequencing, a heterozygous missense variant (c.1150C > T, p.Arg384Trp) in COL9A3 was identified. According to the ACMG guidelines, this variant is predicted to be pathogenic. In addition, prediction tools found COL9A3 protein of this variant a reduced stability, some changed charge properties, and an altered spatial conformation. Findings expanded the mutational spectrum of LDH and contributed to the understanding of COL9A3 in the pathogenesis of LDH.

Hearing Loss in Stickler Syndrome: An Update

Stickler syndrome is a connective tissue disorder characterized by ocular, skeletal, orofacial and auditory manifestations. Its main symptoms are high myopia, retinal detachment, joint hypermobility, early osteoarthritis, cleft palate, midfacial hypoplasia, micrognathia and hearing loss. Large phenotypical variability is apparent and partly explained by the underlying genetic heterogeneity, including collagen genes (COL2A1, COL11A1, COL11A2, COL9A1, COL9A2, COL9A3) and non-collagen genes (BMP4, LRP2, LOXL3). The most frequent type of Stickler syndrome (COL2A1) is characterized by a rather mild high-frequency sensorineural hearing loss in about half of the patients. COL11A1- and COL11A2-related Stickler syndrome results in more frequent hearing loss, being moderate and involving all frequencies. Hearing loss in the rarer types of Stickler syndrome depends on the gene expression in the cochlea, with moderate to severe downsloping hearing loss for Stickler syndrome caused by biallelic type IX collagen gene mutations and none or mild hearing loss for the non-collagen genes. Inherent to the orofacial manifestations, middle ear problems and temporary conductive hearing loss, especially at young age, are also prevalent. Consequently, hearing loss should be actively sought for and adequately treated in Stickler syndrome patients given its high prevalence and the concomitant visual impairment in most patients.

USP3 promotes gastric cancer progression and metastasis by deubiquitination-dependent COL9A3/COL6A5 stabilisation

As an important regulator of intracellular protein degradation, the mechanism of the deubiquitinating enzyme family in tumour metastasis has received increasing attention. Our previous study revealed that USP3 promotes tumour progression and is highly expressed in gastric cancer (GC). Herein, we report two critical targets, COL9A3 and COL6A5, downstream of USP3, via the isobaric tags for relative and absolute quantification technique. Mechanistically, we observed that USP3 interacted with and stabilised COL9A3 and COL6A5 via deubiquitination in GC. Importantly, we found that COL9A3 and COL6A5 were essential mediators of USP3-modulated oncogenic activity in vitro and in vivo. Examination of clinical samples confirmed that elevated expression of USP3, concomitant with increased COL9A3 and COL6A5 abundance, correlates with human GC progression. These data suggest that USP3 promotes GC progression and metastasis by deubiquitinating COL9A3 and COL6A5. These findings identify a mechanism of GC metastasis regarding USP3-mediated deubiquitinating enzyme activity and suggest potential therapeutic targets for GC management.

SOX9-COL9A3-dependent regulation of choroid plexus epithelial polarity governs blood-cerebrospinal fluid barrier integrity

The choroid plexus (CP) is an extensively vascularized neuroepithelial tissue that projects into the brain ventricles. The restriction of transepithelial transport across the CP establishes the blood-cerebrospinal fluid (CSF) barrier that is fundamental to the homeostatic regulation of the central nervous system microenvironment. However, the molecular mechanisms that control this process remain elusive. Here we show that the genetic ablation of Sox9 in the hindbrain CP results in a hyperpermeable blood-CSF barrier that ultimately upsets the CSF electrolyte balance and alters CSF protein composition. Mechanistically, SOX9 is required for the transcriptional up-regulation of Col9a3 in the CP epithelium. The reduction of Col9a3 expression dramatically recapitulates the blood-CSF barrier defects of Sox9 mutants. Loss of collagen IX severely disrupts the structural integrity of the epithelial basement membrane in the CP, leading to progressive loss of extracellular matrix components. Consequently, this perturbs the polarized microtubule dynamics required for correct orientation of apicobasal polarity and thereby impedes tight junction assembly in the CP epithelium. Our findings reveal a pivotal cascade of SOX9-dependent molecular events that is critical for construction of the blood-CSF barrier.

The Lysine Specific Demethylase-1 Negatively Regulates the COL9A1 Gene in Human Articular Chondrocytes

Osteoarthritis (OA) is a degenerative disease of the joints which is associated with an impaired production of the cartilage matrix by the chondrocytes. Here, we investigated the role of Lysine-Specific Demethylase-1 (LSD1), a chromatin remodeling enzyme whose role in articular chondrocytes was previously associated with a catabolic activity and which is potentially involved during OA. Following a loss of function strategy and RNA sequencing analysis, we detail the genes which are targeted by LSD1 in human articular chondrocytes and identify COL9A1, a gene encoding the α1 chain of the cartilage-specific type IX collagen, as negatively regulated by LSD1. We show that LSD1 interacts with the transcription factor SOX9 and is recruited to the promoter of COL9A1. Interestingly, we observe that OA cartilage displays stronger LSD1 immunostaining compared with normal, and we demonstrate that the depletion of LSD1 in OA chondrocytes prevents the decrease in COL9A1 following Il-1β treatment. These results suggest LSD1 is a new regulator of the anabolic activity of articular chondrocytes potentially destabilizing the cartilage matrix, since it negatively regulates COL9A1, a gene encoding a crucial anchoring collagen molecule. This newly identified role played by LSD1 may thus participate in the alteration of the cartilage matrix during OA.

Relationship of COL9A1 and SOX9 Genes with Genetic Susceptibility of Postmenopausal Osteoporosis

As one of the most common types of osteoporosis, postmenopausal osteoporosis (PMOP) is caused by both genetic and environmental factors. Previous studies have indicated that SOX9 activity is tightly regulated to ensure normal bone mineral density (BMD) in the adult skeleton, and the COL9A1 promoter region can be transactivated by SOX9. In this study, we aimed to investigate the potential association between PMOP and the COL9A1 and SOX9 genes. A total of 10,443 postmenopausal women, including 2288 patients and 3557 controls in the discovery stage and 1566 patients and 3032 controls in the validation stage, were recruited. Forty-three tag SNPs (36 in COL9A1 and 7 in SOX9) were selected for genotyping to evaluate the association of the SOX9 gene with PMOP and BMD. Association and bioinformatics analyses were performed for PMOP. BMD and serum level of SOX9 were also utilized as quantitative phenotypes in further analyses. SNP rs73354570 of SOX9 was significantly associated with PMOP in both discovery stages (OR 1.24 [1.10-1.39], P = 3.56 × 10^-4, χ² = 12.75) and combined samples (OR 1.25 [1.15-1.37], P = 5.25 × 10^-7, χ² = 25.17). Further analyses showed that the SNP was also significantly associated with BMD and serum levels of the SOX9 protein. Our results provide further supportive evidence for the association of the SOX9 gene with PMOP and of the SOX9 gene with the variation of BMD in postmenopausal Han Chinese women. This study supports a role for SOX9 in the etiology of PMOP, adding to the current understanding of the susceptibility of osteoporosis.

Clinical, histopathological and genetic characterisation of oculoskeletal dysplasia in the Northern Inuit Dog

Seven Northern Inuit Dogs (NID) were diagnosed by pedigree analysis with an autosomal recessive inherited oculoskeletal dysplasia (OSD). Short-limbed dwarfism, angular limb deformities and a variable combination of macroglobus, cataracts, lens coloboma, microphakia and vitreopathy were present in all seven dogs, while retinal detachment was diagnosed in five dogs. Autosomal recessive OSD caused by COL9A3 and COL9A2 mutations have previously been identified in the Labrador Retriever (dwarfism with retinal dysplasia 1-drd1) and Samoyed dog (dwarfism with retinal dysplasia 2-drd2) respectively; both of those mutations were excluded in all affected NID. Nine candidate genes were screened in whole genome sequence data; only one variant was identified that was homozygous in two affected NID but absent in controls. This variant was a nonsense single nucleotide polymorphism in COL9A3 predicted to result in a premature termination codon and a truncated protein product. This variant was genotyped in a total of 1,232 dogs. All seven affected NID were homozygous for the variant allele (T/T), while 31/116 OSD-unaffected NID were heterozygous for the variant (C/T) and 85/116 were homozygous for the wildtype allele (C/C); indicating a significant association with OSD (p = 1.41x10-11). A subset of 56 NID unrelated at the parent level were analysed to determine an allele frequency of 0.08, estimating carrier and affected rates to be 15% and 0.6% respectively in NID. All 1,109 non-NID were C/C, suggesting the variant is rare or absent in other breeds. Expression of retinal mRNA was similar between an OSD-affected NID and OSD-unaffected non-NID. In conclusion, a nonsense variant in COL9A3 is strongly associated with OSD in NID, and appears to be widespread in this breed.

Exome-wide copy number variation analysis identifies a COL9A1 in frame deletion that is associated with hearing loss

Pathogenic variants in COL9A1 are primarily associated with autosomal recessive Stickler syndrome. Patients with COL9A1-associated Stickler syndrome (STL) present hearing loss (HL), ophthalmic manifestations and skeletal abnormalities. However, the clinical spectrum of patients with COL9A1 variants can also include multiple epiphyseal dysplasia, as well as non-syndromic HL that was observed in one previously reported proband. Exome sequencing was performed on the genomic DNA of an Iranian patient and his affected brother who both report non-syndromic HL. A 44.6 kb homozygous in-frame deletion spanning exons 6 to 33 of COL9A1 was detected via exome-based copy number variation analysis. The deleted exons were confirmed by PCR in the patient and his affected brother, who both have non-syndromic HL. Segregation analysis via qPCR confirmed the parents as heterozygous deletion carriers. Breakpoint analysis mapped the homozygous deletion spanning introns 5 to 33 (g.70,948,188_70,997,277del, NM_001851.4(COL9A1):c.697-3754_2112+769del, p.(Phe233_Ser704del), with an additional 67 bp of inserted intronic sequence that may have originated due to a fork stalling and template switching/microhomology-mediated break-induced replication (FoSTeS/MMBIR) mechanism. This mechanism has not been previously implicated in HL or STL. This is also the first reported copy number variation in COL9A1 that was identified through an exome data set in an Iranian family with apparent non-syndromic HL. The present study emphasizes the importance of exome-wide copy number variation analysis in molecular diagnosis and provides supporting evidence to associate COL9A1 with autosomal recessive non-syndromic HL.

Variants in FAT1 and COL9A1 genes in male population with or without substance use to assess the risk factors for oral malignancy

A number of genetic variants were suggested to be associated with oral malignancy, few variants can be replicated. The aim of this study was to identify significant variants that enhanced personal risk prediction for oral malignancy. A total of 360 patients diagnosed with oral squamous cell carcinoma, 486 controls and 17 newly diagnosed patients with OPMD including leukoplakia or oral submucous fibrosis were recruited. Fifteen tagSNPs which were derived from somatic mutations were genotyped and examined in associations with the occurrence of oral malignancy. Environmental variables along with the SNPs data were used to developed risk predictive models for oral malignancy occurrence. The stepwise model analysis was conducted to fit the best model in an economically efficient way. Two tagSNPs, rs28647489 in FAT1 gene and rs550675 in COL9A1 gene, were significantly associated with the risk of oral malignancy. The sensitivity and specificity were 85.7% and 85.5%, respectively (area under the receiver operating characteristic curve (AUC) was 0.91) for predicting oral squamous cell carcinoma occurrence with the combined genetic variants, betel-quid, alcohol and age. The AUC for OPMD was only 0.69. The predictive probability of squamous cell carcinoma occurrence for genetic risk score without substance use increased from 10% up to 43%; with substance use increased from 73% up to 92%. Genetic variants with or without substance use may enhance risk prediction for oral malignancy occurrence in male population. The prediction model may be useful as a clinical index for oral malignancy occurrence and its risk assessments.

Characterization of Chondrogenic Gene Expression and Cartilage Phenotype Differentiation in Human Breast Adipose-Derived Stem Cells Promoted by Ginsenoside Rg1 In Vitro

BACKGROUND/AIMS

Investigating and understanding chondrogenic gene expression during the differentiation of human breast adipose-derived stem cells (HBASCs) into chondrogenic cells is a prerequisite for the application of this approach for cartilage repair and regeneration. In this study, we aim to characterize HBASCs and to examine chondrogenic gene expression in chondrogenic inductive culture medium containing ginsenoside Rg1.

METHODS

Human breast adipose-derived stem cells at passage 3 were evaluated based on specific cell markers and their multilineage differentiation capacity. Cultured HBASCs were treated either with basic chondrogenic inductive conditioned medium alone (group A, control) or with basic chondrogenic inductive medium plus 10 µg/ml (group B), 50 µg/ml (group C), or 100µg/ml ginsenoside Rg1 (group D). Cell proliferation was assessed using the CCK-8 assay for a period of 9 days. Two weeks after induction, the expression of chondrogenic genes (collagen type II, collagen type XI, ACP, COMP and ELASTIN) was determined using real-time PCR in all groups.

RESULTS

The different concentrations of ginsenoside Rg1 that were added to the basic chondrogenic inductive culture medium promoted the proliferation of HBASCs at earlier stages (groups B, C, and D) but resulted in chondrogenic phenotype differentiation and higher mRNA expression of collagen type II (CO-II), collagen type XI (CO-XI), acid phosphatase (ACP), cartilage oligomeric matrix protein (COMP) and ELASTIN compared with the control (group A) at later stages. The results reveal an obvious positive dose-effect relationship between ginsenoside Rg1 and the proliferation and chondrogenic phenotype differentiation of HBASCs in vitro.

CONCLUSIONS

Human breast adipose-derived stem cells retain stem cell characteristics after expansion in culture through passage 3 and serve as a feasible source of cells for cartilage regeneration in vitro. Chondrogenesis in HBASCs was found to be prominent after chondrogenic induction in conditions containing ginsenoside Rg1.

Association of collagen I, IX and vitamin D receptor gene polymorphisms with radiological severity of intervertebral disc degeneration in Southern European Ancestor

PURPOSE

Several genomic loci have been previously found to be associated with intervertebral disc degeneration, so far. Data are mostly derived from northern European countries whereas data derived from Southern European Ancestor are limited. This study aimed to evaluate the association between radiological disease severity of lumbar disc degeneration and certain genetic loci in a sample of participants from Southern Europe.

METHODS

Seventy-five patients with mild to severe lumbar disc degeneration and 25 healthy controls were enrolled into the study. In each subject, each lumbar intervertebral disc was separately examined to obtain a total radiological score for disease severity. In addition, single-nucleotide polymorphisms of predefined genetic samples were analyzed in all participants: COL1A1 Sp1, COL9a2 Trp2, COL9a3 Trp3, and VDR TaqI.

RESULTS

Degeneration scores were significantly worse in cases with COL1A1 Sp1, COL9a3 Trp3, and VDR TaqI mutations; however, COL9a2 Trp2 mutation was not associated with a difference in the severity of disc degeneration. In addition, subjects with mutation in more than one gene sample (n = 20) had significantly worse degeneration scores than the remaining study participants (n = 80) (17.70 ± 2.72 vs. 21.81 ± 1.81, p < 0.001).

CONCLUSION

Single-nucleotide polymorphisms occurring in COL1A1, COL9a3 and VDR genes seem to be associated with the development of lumbar disc degeneration in this cohort, possibly with even more pronounced association when multiple mutations are present in the same individual. By further prospective twin studies in associated genes and analyses of their relationship with environmental factors in an internationally sampled large cohort will make a more clear-minded conclusion about their association with disc degeneration, which would yield better appreciation and clinical planning of some predisposed people for these pathologies.

Canine Mammary Tumours Are Affected by Frequent Copy Number Aberrations, including Amplification of MYC and Loss of PTEN

BACKGROUND

Copy number aberrations frequently occur during the development of many cancers. Such events affect dosage of involved genes and may cause further genomic instability and progression of cancer. In this survey, canine SNP microarrays were used to study 117 canine mammary tumours from 69 dogs.

RESULTS

We found a high occurrence of copy number aberrations in canine mammary tumours, losses being more frequent than gains. Increased frequency of aberrations and loss of heterozygosity were positively correlated with increased malignancy in terms of histopathological diagnosis. One of the most highly recurrently amplified regions harbored the MYC gene. PTEN was located to a frequently lost region and also homozygously deleted in five tumours. Thus, deregulation of these genes due to copy number aberrations appears to be an important event in canine mammary tumour development. Other potential contributors to canine mammary tumour pathogenesis are COL9A3, INPP5A, CYP2E1 and RB1. The present study also shows that a more detailed analysis of chromosomal aberrations associated with histopathological parameters may aid in identifying specific genes associated with canine mammary tumour progression.

CONCLUSIONS

The high frequency of copy number aberrations is a prominent feature of canine mammary tumours as seen in other canine and human cancers. Our findings share several features with corresponding studies in human breast tumours and strengthen the dog as a suitable model organism for this disease.

Hox10-regulated endodermal cell migration is essential for development of the ascidian intestine

Hox cluster genes play crucial roles in development of the metazoan antero-posterior axis. Functions of Hox genes in patterning the central nervous system and limb buds are well known. They are also expressed in chordate endodermal tissues, where their roles in endodermal development are still poorly understood. In the invertebrate chordate, Ciona intestinalis, endodermal tissues are in a premature state during the larval stage, and they differentiate into the digestive tract during metamorphosis. In this study, we showed that disruption of a Hox gene, Ci-Hox10, prevented intestinal formation. Ci-Hox10-knock-down larvae displayed defective migration of endodermal strand cells. Formation of a protrusion, which is important for cell migration, was disrupted in these cells. The collagen type IX gene is a downstream target of Ci-Hox10, and is negatively regulated by Ci-Hox10 and a matrix metalloproteinase ortholog, prior to endodermal cell migration. Inhibition of this regulation prevented cellular migration. These results suggest that Ci-Hox10 regulates endodermal strand cell migration by forming a protrusion and by reconstructing the extracellular matrix.

COL9A1 gene polymorphism is associated with Kashin-Beck disease in a northwest Chinese Han population

Objective

We sought to determine whether genomic polymorphism in collagen IX genes (COL9A) was associated with Kashin-Beck disease (KBD).

Methods

Twenty seven single nucleotide polymorphisms (SNPs) in COL9AI, COL9A2 and COL9A3 were genotyped in 274 KBD cases and 248 healthy controls using the Sequenom MassARRAY system. Associations between the COL9A polymorphism and KBD risk were detected using an unconditional logistic regression model. Linkage disequilibrium (LD) and haplotypes analysis were performed with the Haploview software.

Results

After Bonferroni correction, the frequency distribution of genotypes in rs6910140 in COL9A1 was significantly different between the KBD and the control groups (X² = 16.74, df = 2, P = 0.0002). Regression analysis showed that the allele “C” in SNP rs6910140 had a significant protective effect on KBD [odds ratio (OR) = 0.49, 95% confidence interval (CI) = 0.34–0.70, P = 0.0001]. The frequencies of alleles and genotypes in rs6910140 were significantly different among subjects of different KBD stages (allele: X² = 7.82, df = 2, P = 0.02, genotype: X² = 14.81, df = 4, P = 0.005). However, haplotype analysis did not detect any significant association between KBD and COL9A1, COL9A2 and COL9A3.

Conclusions

We observed a significant association between rs6910140 of COL9A1 and KBD, suggesting a role of COL9A1 in the development of KBD.

New developmental evidence clarifies the evolution of wrist bones in the dinosaur-bird transition

A new study that integrates developmental and paleontological data reveals previously unsuspected evolutionary transformations during the emergence of the bird wrist, consistent with its derivation from non-avian dinosaurs.

From early dinosaurs with as many as nine wrist bones, modern birds evolved to develop only four ossifications. Their identity is uncertain, with different labels used in palaeontology and developmental biology. We examined embryos of several species and studied chicken embryos in detail through a new technique allowing whole-mount immunofluorescence of the embryonic cartilaginous skeleton. Beyond previous controversy, we establish that the proximal–anterior ossification develops from a composite radiale+intermedium cartilage, consistent with fusion of radiale and intermedium observed in some theropod dinosaurs. Despite previous claims that the development of the distal–anterior ossification does not support the dinosaur–bird link, we found its embryonic precursor shows two distinct regions of both collagen type II and collagen type IX expression, resembling the composite semilunate bone of bird-like dinosaurs (distal carpal 1+distal carpal 2). The distal–posterior ossification develops from a cartilage referred to as “element x,” but its position corresponds to distal carpal 3. The proximal–posterior ossification is perhaps most controversial: It is labelled as the ulnare in palaeontology, but we confirm the embryonic ulnare is lost during development. Re-examination of the fossil evidence reveals the ulnare was actually absent in bird-like dinosaurs. We confirm the proximal–posterior bone is a pisiform in terms of embryonic position and its development as a sesamoid associated to a tendon. However, the pisiform is absent in bird-like dinosaurs, which are known from several articulated specimens. The combined data provide compelling evidence of a remarkable evolutionary reversal: A large, ossified pisiform re-evolved in the lineage leading to birds, after a period in which it was either absent, nonossified, or very small, consistently escaping fossil preservation. The bird wrist provides a modern example of how developmental and paleontological data illuminate each other. Based on all available data, we introduce a new nomenclature for bird wrist ossifications.

When birds diverged from nonavian dinosaurs, one of the key adaptations for flight involved a remodelling of the bones of the wrist. However, the correspondence between bird and dinosaur wrist bones is controversial. To identify the bones in the bird wrist, data can be drawn from two radically different sources: (1) embryology and (2) the fossil record of the dinosaur–bird transition. Currently, identifications are uncertain, but new developmental data can help resolve apparent conflicts. The modern bird wrist comprises four ossifications, arranged roughly in a square with its sides running proximal/distal and anterior/posterior. Our study integrates developmental and paleontological data and clarifies the relationship between each of these four ossifications and those found in nonavian dinosaurs. This integrative approach resolves previous disparities that have challenged the support for the dinosaur–bird link and reveals previously undetected processes, including loss, fusion, and in one case, re-evolution of a transiently lost bone.

Autosomal recessive Stickler syndrome due to a loss of function mutation in the COL9A3 gene

Stickler syndrome (STL) is a clinically variable and genetically heterogeneous syndrome characterized by ophthalmic, articular, orofacial, and auditory manifestations. STL has been described with both autosomal dominant and recessive inheritance. The dominant form is caused by mutations of COL2A1 (STL 1, OMIM 108300), COL11A1 (STL 2, OMIM 604841), and COL11A2 (STL 3, OMIM 184840) genes, while recessive forms have been associated with mutations of COL9A1 (OMIM 120210) and COL9A2 (OMIM 120260) genes. Type IX collagen is a heterotrimeric molecule formed by three genetically distinct chains: α1, α2, and α3 encoded by the COL9A1, COL9A2, and COL9A3 genes. Up to this time, only heterozygous mutations of COL9A3 gene have been reported in human and related to: (1) multiple epiphyseal dysplasia type 3, (2) susceptibility to an intervertebral disc disease, and (3) hearing loss. Here, we describe the first autosomal recessive Stickler family due to loss of function mutations (c.1176_1198del, p.Gln393Cysfs*25) of COL9A3 gene. These findings extend further the role of collagen genes family in the disease pathogenesis.

Nuclear factor Y (NF-Y) regulates the proximal promoter activity of the mouse collagen α1(XI) gene (Col11a1) in chondrocytes

Type XI collagen, a heterotrimer composed of α1(XI), α2(XI), and α3(XI), plays a critical role in cartilage formation and in skeletal morphogenesis. However, the transcriptional regulation of α1(XI) collagen gene (Col11a1) in chondrocyte is poorly characterized. In this study, we investigated the proximal promoter of mouse Col11a1 gene in chondrocytes. Major transcription start site was located at -299 bp upstream of the translation start site, and the proximal promoter lacks a TATA sequence but has a high guanine-cytosine (GC) content. Cell transfection experiments demonstrated that the segment from -116 to -256 is necessary for activation of the proximal Col11a1 promoter, and an electrophoretic mobility shift assay showed that a nuclear protein is bound to the segment from -116 to -176 in this promoter. Additional comparative and in silico analyses demonstrated that an ATTGG sequence, which is critical for binding to nuclear factor Y (NF-Y), is within the highly conserved region from -135 to -145. Interference assays using wild-type and mutant oligonucleotide or with specific antibody revealed that NF-Y protein is bound to this region. Cell transfection experiments with reporter constructs in the absence of NF-Y binding sequence exhibited the suppression of the promoter activity. Furthermore, chromatin immunoprecipitation assay demonstrated that NF-Y protein is directly bound to this region in vivo, and overexpression of dominant-negative NF-Y A mutant also inhibited the proximal promoter activity. Taken together, these results indicate that the transcription factor NF-Y regulates the proximal promoter activity of mouse Col11a1 gene in chondrocytes.

CNV analysis in Tourette syndrome implicates large genomic rearrangements in COL8A1 and NRXN1

Tourette syndrome (TS) is a neuropsychiatric disorder with a strong genetic component. However, the genetic architecture of TS remains uncertain. Copy number variation (CNV) has been shown to contribute to the genetic make-up of several neurodevelopmental conditions, including schizophrenia and autism. Here we describe CNV calls using SNP chip genotype data from an initial sample of 210 TS cases and 285 controls ascertained in two Latin American populations. After extensive quality control, we found that cases (N = 179) have a significant excess (P = 0.006) of large CNV (>500 kb) calls compared to controls (N = 234). Amongst 24 large CNVs seen only in the cases, we observed four duplications of the COL8A1 gene region. We also found two cases with ∼400 kb deletions involving NRXN1, a gene previously implicated in neurodevelopmental disorders, including TS. Follow-up using multiplex ligation-dependent probe amplification (and including 53 more TS cases) validated the CNV calls and identified additional patients with rearrangements in COL8A1 and NRXN1, but none in controls. Examination of available parents indicates that two out of three NRXN1 deletions detected in the TS cases are de-novo mutations. Our results are consistent with the proposal that rare CNVs play a role in TS aetiology and suggest a possible role for rearrangements in the COL8A1 and NRXN1 gene regions.

Epigenetic regulation during fetal femur development: DNA methylation matters

Epigenetic modifications are heritable changes in gene expression without changes in DNA sequence. DNA methylation has been implicated in the control of several cellular processes including differentiation, gene regulation, development, genomic imprinting and X-chromosome inactivation. Methylated cytosine residues at CpG dinucleotides are commonly associated with gene repression; conversely, strategic loss of methylation during development could lead to activation of lineage-specific genes. Evidence is emerging that bone development and growth are programmed; although, interestingly, bone is constantly remodelled throughout life. Using human embryonic stem cells, human fetal bone cells (HFBCs), adult chondrocytes and STRO-1⁺ marrow stromal cells from human bone marrow, we have examined a spectrum of developmental stages of femur development and the role of DNA methylation therein. Using pyrosequencing methodology we analysed the status of methylation of genes implicated in bone biology; furthermore, we correlated these methylation levels with gene expression levels using qRT-PCR and protein distribution during fetal development evaluated using immunohistochemistry. We found that during fetal femur development DNA methylation inversely correlates with expression of genes including iNOS (NOS2) and COL9A1, but not catabolic genes including MMP13 and IL1B. Furthermore, significant demethylation was evident in the osteocalcin promoter between the fetal and adult developmental stages. Increased TET1 expression and decreased expression of DNA (cytosine-5-)-methyltransferase 1 (DNMT1) in adult chondrocytes compared to HFBCs could contribute to the loss of methylation observed during fetal development. HFBC multipotency confirms these cells to be an ideal developmental system for investigation of DNA methylation regulation. In conclusion, these findings demonstrate the role of epigenetic regulation, specifically DNA methylation, in bone development, informing and opening new possibilities in development of strategies for bone repair/tissue engineering.

Pseudoachondroplasia and multiple epiphyseal dysplasia: a 7-year comprehensive analysis of the known disease genes identify novel and recurrent mutations and provides an accurate assessment of their relative contribution

Pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED) are relatively common skeletal dysplasias resulting in short-limbed dwarfism, joint pain, and stiffness. PSACH and the largest proportion of autosomal dominant MED (AD-MED) results from mutations in cartilage oligomeric matrix protein (COMP); however, AD-MED is genetically heterogenous and can also result from mutations in matrilin-3 (MATN3) and type IX collagen (COL9A1, COL9A2, and COL9A3). In contrast, autosomal recessive MED (rMED) appears to result exclusively from mutations in sulphate transporter solute carrier family 26 (SLC26A2). The diagnosis of PSACH and MED can be difficult for the nonexpert due to various complications and similarities with other related diseases and often mutation analysis is requested to either confirm or exclude the diagnosis. Since 2003, the European Skeletal Dysplasia Network (ESDN) has used an on-line review system to efficiently diagnose cases referred to the network prior to mutation analysis. In this study, we present the molecular findings in 130 patients referred to ESDN, which includes the identification of novel and recurrent mutations in over 100 patients. Furthermore, this study provides the first indication of the relative contribution of each gene and confirms that they account for the majority of PSACH and MED.

[Expression of COL9A1 gene and its polymorphism in children with idiopathic congenital talipes equinovarus]

OBJECTIVE

COL9A1 gene is located in the susceptibility region of idiopathic congenital talipes equinovarus (ICTEV) (6q12-13). This study aimed to investigate the expression of the COL9A1 gene and the distribution of single nucleotide polymorphism (SNP) of COL9A1 gene in patients with ICTEV and normal controls.

METHODS

Immunohistochemistry was used to detect the expression of COL9A1 in 25 children with ICTEV and 5 normal controls. The frequencies of genotypes and allele of two SNPs in COL9A1 gene rs35470562 and rs1135056 were investigated by PCR-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing in 118 patients with ICTEV and 100 normal controls.

RESULTS

The COL9A1 protein expression was significantly higher in 22 (88%) out of 25 children with ICTEV than normal controls. There were significant differences in the frequencies of genotypes and allele of rs1135056 in COL9A1 gene between the ICTEV and the control groups: the G allele frequency was higher, the frequency of AA genotype was lower, and the frequencies of AG and GG genotypes were higher in ICTEV patients than those in healthy controls (P<0.05).

CONCLUSIONS

COL9A1 protein is highly expressed in patients with ICTEV and rs1135056, which is located in the coding region of COL9A1 gene, may be associated with the pathogenesis of ICTEV.

[Bone and joint diseases in children. Skeletal dysplasia in children--unrecognized cases in daily practice]

Skeletal dysplasia is a group of diseases caused by aberration of growth, development and differentiation of skeletal tissues including bone and cartilage. Most of the diseases that belong to skeletal dysplasia are monogenic diseases. Diagnosis of skeletal dysplasia during childhood is easier than those in other period of life ; usually we can diagnose them clinically by their characteristic radiographic features and confirm the diagnosis by genetic test when the disease genes are known. However, some skeletal dysplasias may escape from detection because of their mild phenotypes and lack of diagnostic complications, and may be diagnosed as common orthopedic diseases. Here, we present several cases of such skeletal dysplasia that we experienced in our daily practice and highlight diagnostic problems. For correct diagnosis of skeletal dysplasia, it is important to consider its possibility always in the clinical practice and to collect clinical information appropriately, including those regarding family history. The collect diagnosis would lead to better treatment and care for patients and families.

Multiple epiphyseal dysplasia

BACKGROUND

Multiple epiphyseal dysplasia (MED) is a common genetically and clinically heterogeneous skeletal dysplasia characterized by early-onset osteoarthritis, mainly in the hip and knee, and mild-to-moderate short stature. Here we report on a 6-generation MED family with 17 affected members.

METHOD

The clinical and radiographic data on the 12 affected members still living were scrutinized. A structured inquiry comprising state of health and MED-related symptoms since birth up to the present time and the osteoarthritis outcome (KOOS) questionnaire were sent to all living family members with MED. The 5 known gene loci for autosomal dominant MED were analyzed for linkage, using fluorescence-labeled microsatellite markers. Linkage was ascertained with markers close to the COL9A2 gene, which was analyzed for mutations by sequencing.

RESULTS

We identified an exon 3 donor splice mutation in the COL9A2 gene in all affected family members. Clinical, radiographic, and questionnaire data from affected family members suggested that MED caused by COL9A2 mutations starts in early childhood with knee pain accompanied by delayed ossification of femoral epiphyses. The disease then either stabilizes during puberty or progresses with additional joints becoming affected; joint surgery might be necessary. The progression of the disease also affects muscles, with increasing atrophy, resulting in muscle fatigue and pain. Muscular atrophy has not been reported earlier in cases with COL9A2 mutations.

INTERPRETATION

In a patient with clinically suspected or verified MED, it is important to perform DNA-based analysis to identify a possible disease-causing mutation. This information can be used to carry out genetic risk assessment of other family members and to achieve an early and correct diagnosis in the children.

Collagen IX is required for the integrity of collagen II fibrils and the regulation of vascular plexus formation in zebrafish caudal fins

Capillary plexuses form during both vasculogenesis and angiogenesis and are remodeled into mature vessel types and patterns which are delicately orchestrated with the sizes and shapes of other tissues and organs. We isolated a zebrafish mutation named prp (for persistent plexus) that causes persistent formation of vascular plexuses in the caudal fins and consequent mispatterning of bony fin rays and the fin shape. Detailed analyses revealed that the prp mutation causes a significant reduction in the size and dramatic structural defects in collagen II-rich extracellular matrices called actinotrichia of both embryonic finfolds and adult fins. prp was mapped to chromosome 19 and found to encode the zebrafish collagen9alpha1 (col9alpha1) gene which is abundantly expressed in developing finfolds. A point mutation resulting in a leucine-to-histidine change was detected in the thrombospondin domain of the col9alpha1 gene in prp. Morpholino-mediated knockdown of col9alpha1 phenocopied the prp small-finfold phenotype in wild-type embryos, and an injection of plasmids containing the col9alpha1 cDNA into prp embryos locally restored the finfold size. Furthermore, we found that osteoblasts in prp mutants were mispatterned apparently following the abnormal vascular plexus pattern, demonstrating that blood vessels play an important role in the patterning of bony rays in zebrafish caudal fins.

Serum antibodies against intact human collagen IX are elevated at onset of rheumatoid arthritis but are not related to development of erosions

OBJECTIVE

To measure the presence of autoantibodies binding to intact human recombinant collagen IX and assess their usefulness as a diagnostic marker and an indicator of disease activity in rheumatoid arthritis (RA).

METHODS

Recombinant human full-length collagen IX (rCIX) was produced in a baculovirus expression system and purified for use in ELISA developed to detect antibodies to native and denatured collagen IX. Fifty-three patients with recent-onset rheumatoid factor-seropositive RA were analyzed for the presence of rCIX antibodies of the IgG type at the time of initial diagnosis and after 3, 6, 12, and 24 months of followup. The RA sera were accompanied by 30 controls. Associations were determined between patients' antibody titers, development of erosions in the hands and feet, and various clinical and laboratory markers.

RESULTS

Serum antibody levels among patients with RA at time of diagnosis were 1.78 times higher against native rCIX (p < 0.001) and 1.71 times higher against denatured rCIX (p < 0.001) than in the controls, and they remained high during the followup. No correlation was seen between antibody levels and clinical and laboratory findings.

CONCLUSION

Our data show that patients with recent-onset RA have significantly elevated levels of autoantibodies to human rCIX. These autoantibodies were observed already at the early stages of the disease, which may reflect their diagnostic potential in RA.

Regulation of skeletogenic differentiation in cranial dermal bone

Although endochondral ossification of the limb and axial skeleton is relatively well-understood, the development of dermal (intramembranous) bone featured by many craniofacial skeletal elements is not nearly as well-characterized. We analyzed the expression domains of a number of markers that have previously been associated with endochondral skeleton development to define the cellular transitions involved in the dermal ossification process in both chick and mouse. This led to the recognition of a series of distinct steps in the dermal differentiation pathways, including a unique cell type characterized by the expression of both osteogenic and chondrogenic markers. Several signaling molecules previously implicated in endochondrial development were found to be expressed during specific stages of dermal bone formation. Three of these were studied functionally using retroviral misexpression. We found that activity of bone morphogenic proteins (BMPs) is required for neural crest-derived mesenchyme to commit to the osteogenic pathway and that both Indian hedgehog (IHH) and parathyroid hormone-related protein (PTHrP, PTHLH)negatively regulate the transition from preosteoblastic progenitors to osteoblasts. These results provide a framework for understanding dermal bone development with an aim of bringing it closer to the molecular and cellular resolution available for the endochondral bone development.

Expression of cartilage-related genes in bovine synovial tissue

The synovium contains mesenchymal stem cells with chondrogenic potential. Although synovial and articular cartilage tissue develop from a common pool of mesenchymal cells, little is known about their genetic commonalities. In the present study, the mRNA levels for several cartilage-related proteins, namely, cartilage oligomeric matrix protein (COMP), Sox9, aggrecan, and collagen types I, II, IX, X, and XI, were measured using the real-time polymerase chain reaction. Our data reveal the synovium of calf metacarpal joints to physiologically express not only type I collagen but also COMP, Sox9, aggrecan, and collagen types X and XI. The mRNA levels for the latter five proteins lie between 2% and 15% of those in articular cartilage. We speculate that these genes are being expressed by chondroprogenitor cells, whose presence in the synovium reflects a common ontogenetic phase in the fetal development of this tissue and of articular cartilage.

Occupational and genetic risk factors associated with intervertebral disc disease

STUDY DESIGN

Cross-sectional epidemiologic study.

OBJECTIVE

To evaluate the interaction between known genetic risk factors and whole-body vibration for symptomatic intervertebral disc disease (IDD) in an occupational sample.

SUMMARY OF BACKGROUND DATA

Risk factors of IDD include, among others, whole-body vibration and heredity. In this study, the importance of a set of known genetic risk factors and whole-body vibration was evaluated in an occupational sample of train engineers and sedentary controls.

METHODS

Eleven variations in 8 genes (COL9A2, COL9A3, COL11A2, IL1A, IL1B, IL6, MMP-3, and VDR) were genotyped in 150 male train engineers with an average of 21-year exposure to whole-body vibration and 61 male paper mill workers with no exposure to vibration. Subjects were classified into IDD-phenotype and asymptomatic groups, based on the latent class analysis.

RESULTS

The number of individuals belonging to the IDD-phenotype was significantly higher among train engineers (42% of train engineers vs. 17.5% of sedentary workers; P = 0.005). IL1A -889T allele represented a significant risk factor for the IDD-phenotype both in the single marker allelic association test (P = 0.043) and in the logistic regression analysis (P = 0.01). None of the other allele markers was significantly associated with symptoms when analyzed independently. However, for all the SNP markers considered, whole-body vibration represents a nominally significant risk factor.

CONCLUSION

The results suggest that whole-body vibration is a risk factor for symptomatic IDD. Moreover, whole-body vibration had an additive effect with genetic risk factors increasing the likelihood of belonging to the IDD-phenotype group. Of the independent genetic markers, IL1A -889T allele had strongest association with IDD-phenotype.

ColVa1 and ColXIa1 are required for myocardial morphogenesis and heart valve development

Genetic mutations in minor fibrillar collagen types Va1 (ColVa1) and XIa1 (ColXI) have been identified in connective tissue disorders including Ehlers-Danlos syndrome and chondrodysplasias. ColVa1+/- and ColXIa1-/- mutant mice recapitulate these human disorders and show aberrations in collagen fiber organization in connective tissue of the skin, cornea, cartilage, and tendon. In the heart, fibrous networks of collagen fibers form throughout the ventricular myocardium and heart valves, and alterations in collagen fiber homeostasis are apparent in many forms of cardiac disease associated with myocardial dysfunction and valvular insufficiency. There is increasing evidence for cardiac dysfunction in connective tissue disorders, but the mechanisms have not been addressed. ColVa1+/- and ColXIa1-/- mutant mice were used to identify roles for ColVa1 and ColXIa1 in ventricular myocardial morphogenesis and heart valve development. These affected cardiac structures show a compensatory increase in type I collagen deposition, similar to that previously described in valvular and cardiomyopathic disease. Morphological cardiac defects associated with changes in collagen fiber homeostasis identified in ColVa1+/- and ColXIa1-/- mice provide an insight into previously unappreciated forms of cardiac dysfunction associated with connective tissue disorders.

Collagen IX is indispensable for timely maturation of cartilage during fracture repair in mice

Fracture repair recapitulates in adult organisms the sequence of cell biological events of endochondral ossification during skeletal development and growth. After initial inflammation and deposition of granulation tissue, a cartilaginous callus is formed which, subsequently, is remodeled into bone. In part, bone formation is influenced also by the properties of the extracellular matrix of the cartilaginous callus. Deletion of individual macromolecular components can alter extracellular matrix suprastructures, and hence stability and organization of mesenchymal tissues. Here, we took advantage of the collagen IX knockout mouse model to better understand the role of this collagen for organization, differentiation and maturation of a cartilaginous template during formation of new bone. Although a seemingly crucial component of cartilage fibrils is missing, collagen IX-deficient mice develop normally, but are predisposed to premature joint cartilage degeneration. However, we show here that lack of collagen IX alters the time course of callus differentiation during bone fracture healing. The maturation of cartilage matrix was delayed in collagen IX-deficient mice calli as judged by collagen X expression during the repair phase and the total amount of cartilage matrix was reduced. Entering the remodeling phase of fracture healing, Col9a1(-/-) calli retained a larger percentage of cartilage matrix than in wild type indicating also a delayed formation of new bone. We concluded that endochondral bone formation can occur in collagen IX knockout mice but is impaired under conditions of stress, such as the repair of an unfixed fractured long bone.

A Col9a1 enhancer element activated by two interdependent SOX9 dimers

The transcription factor SOX9 plays a critical role in chondrogenesis as well as in sex determination. Previous work has suggested that SOX9 functions as a DNA-dependent dimer when it activates genes involved in chondrogenesis, but functions as a monomer to activate genes involved in sex determination. We present evidence herein for a third binding configuration through which SOX9 can activate transcription. We have identified four separate SOX consensus sequences in a COL9A1 collagen gene enhancer. The sites are arranged as two pairs, and each pair is similar to previously discovered dimeric SOX9 binding sites. Increasing the spacing between the pairs of sites eliminated enhancer activity in chondrocytic cells, as did the mutation of any one of the four sites. The COL9A1 enhancer is ordinarily inactive in 10T1/2 cells, but cotransfection with a SOX9 expression plasmid was sufficient to activate the enhancer, and mutation of any one of the four sites reduced responsiveness to SOX9 overexpression. These results suggest a novel mechanism for transcriptional activation by SOX9, in which two SOX9 dimers that are bound at the two pairs of sites are required to interact with one another, either directly or indirectly, in order to produce a functional transcriptional activation complex.

Analysis of association between COL9A1 gene and idiopathic con-genital talipes equinovarus

Genotypes of 2 SNPs(rs592121 and rs1135056) within COL9A1 gene in 84 ICTEV nuclear pedigrees were analyzed by restriction fragment length polymorphism and DNA sequencing. Analysis of association between SNP locus and ICTEV was performed using ETDT software. Haplotypes and their frequencies in 84 nuclear pedigrees were established and analyzed by TRANSMIT software. RT-PCR was used to detect the expressions of COL9A1 mRNA in 25 patients with ICTEV. The results showed that rs592121 and rs1135056 loci within COL9A1 gene existed transmission disequilibrium in 84 nuclear pedigrees (P<0.05). Expression of COL9A1 on mRNA levels showed significantly higher in patients with ICTEV than in normal person (t=4.7500, P<0.05) . These results indicate that COL9A1 gene may be important suscept-ble genes of ICTEV.

Molecular characterization of the equine collagen, type IX, alpha 2 (COL9A2) gene on horse chromosome 2p16-->p15

The mammalian collagen, type IX, alpha 2 gene (COL9A2) encodes the alpha-2 chain of type IX collagen and is located on horse chromosome 2p16-->p14 harbouring a quantitative trait locus for osteochondrosis. We isolated a bacterial artificial chromosome (BAC) clone containing the equine COL9A2 gene and determined the complete genomic sequence of this gene. Cloning and characterization of equine COL9A2 revealed that the equine gene consists of 32 exons spanning approximately 15 kb. The COL9A2 transcript encodes a single protein of 688 amino acids. Thirty two single nucleotide polymorphisms (SNPs) equally distributed in the gene were detected in a mutation scan of eight unrelated Hanoverian warmblood stallions, including one SNP that affects the amino acid sequence of COL9A2. Comparative analyses between horse, human, mouse and rat indicate that the chromosomal location of equine COL9A2 is in agreement with known chromosomal synteny relationships. The comparison of the gene structure and transcript revealed a high degree of conservation towards the other mammalian COL9A2 genes. We chose three informative SNPs for association and linkage disequilibrium tests in three to five paternal half-sib families of Hanoverian warmblood horses consisting of 44 to 75 genotyped animals. The test statistics did not reach the significance threshold of 5% and so we could not show an association of COL9A2 with equine osteochondrosis.

Age-dependent increase of discoidin domain receptor 2 and matrix metalloproteinase 13 expression in temporomandibular joint cartilage of type IX and type XI collagen-deficient mice

Our previous studies demonstrated that mutations in type IX and type XI collagens in mice caused osteoarthritis (OA)-like changes in knee and temporomandibular (TM) joints. We also found that the overexpression of matrix metalloproteinase 13 (Mmp-13) was probably due to the up-regulation of a collagen receptor, discoidin domain receptor 2 (Ddr2), which was responsible for knee cartilage degeneration in mutant mice. The objective of our study was to determine whether the expression of Mmp-3, Mmp-13 and Ddr2 was increased in OA-like TM joints in mutant mice using immunohistochemistry. We found that the staining for Ddr2, Mmp-13 and Mmp-derived type II collagen fragments in tissue sections from 6-month-old mice was increased in TM joints of the mutant mice. In contrast, we found no difference in the staining for Mmp-3 amongst the two mutant mice and their wild-type littermates. We conclude that, similar to previous observations in knee joints, the overexpression of Ddr2 and Mmp-13 may be responsible for the OA-like change in TM joints in mutant mice.

Pathogenesis of osteoarthritis-like changes in the joints of mice deficient in type IX collagen

OBJECTIVE

To examine the pathogenetic mechanisms of osteoarthritis (OA)-like changes in Col9a1-/- mice, which are deficient in type IX collagen.

METHODS

Knee joints and temporomandibular joints (TMJs) from Col9a1-/- mice and their wild-type (Col9a1+/+) littermates were examined by light microscopy. Immunohistochemical staining was performed to examine the expression of matrix metalloproteinase 3 (MMP-3) and MMP-13, degraded type II collagen, and the discoidin domain receptor 2 (DDR-2) in knee joints. Cartilage mechanics were also evaluated for compressive properties by microindentation testing of the tibial plateau and for tensile properties by osmotic loading of the femoral condyle.

RESULTS

Histologic analysis showed age-dependent OA-like changes in the knee and TMJs of Col9a1-/- mice starting at the age of 3 months. At the age of 6 months, enhanced proteoglycan degradation was observed in the articular cartilage of the knee and TMJs of the mutant mice. The expression of MMP-13 and DDR-2 protein and the amount of degraded type II collagen were higher in the knee joints of Col9a1-/- mice than in their wild-type littermates at the age of 6 months. Changes in cartilage mechanics were observed in the femoral and tibial plateaus of Col9a1-/- mice at 6 months, including a decrease in the compressive modulus and uniaxial modulus. At 3 and 6 months of age, tibial cartilage in Col9a1-/- mice was found to be more permeable to fluid flow, with an associated compromise in the fluid pressurization mechanism of load support. All of these changes occurred only at medial sites.

CONCLUSION

Lack of type IX collagen in Col9a1-/- mice results in age-dependent OA-like changes in the knee joints and TMJs.

[Type IX collagen diseases]

Type IX collagen is a structural protein which consists of the cartilage collagen II/IX/XI heteropolymer. Transgenic mice overexpressing a mutant alpha 1 (IX) collagen chain in cartilage develop a chondrodysplasia-like phenotype associated with early-onset osteoarthritis and spondylosis. Subsequent identifications of the human type IX collagen diseases proved the correctness of the work on mice. Now we know that type IX collagen gene mutations cause multiple epiphyseal dysplasia, an osteochondrodysplasia which frequently features early onset osteoarthritis. Polymorphic variants of the type IX collagen genes are associated with lumbar disc diseases. It is getting more important to understand the biological roles of collagen IX in the musculoskeletal system.

Association study of COL9A2 with lumbar disc disease in the Japanese population

Lumbar disc disease (LDD) is a common musculo-skeletal disease with strong genetic determinants. In a Finnish population, a single nucleotide polymorphism (SNP) causing an amino-acid substitution (Trp2 allele) in COL9A2, which encodes the alpha2 (IX) chain of type IX collagen, has been reported to associate with LDD. However, replication studies in different populations have produced controversial results. To further investigate the association of COL9A2 with LDD in Japanese, we examined SNPs in COL9A2, including Trp2, in 470 LDD patients (mean age 35) along with 658 controls (mean age 48). We identified a total of 43 sequence variations in COL9A2. Nine SNPs, including Trp2, were selected and genotyped. After Bonferroni's correction, none of these SNPs showed association. Unlike observations in the Finnish population, Trp2 was common in Japanese, and no association with LDD was apparent. However, we did see association of a COL9A2 specific haplotype with LDD (P=0.025; permutation test); this association is more significant in patients with severe lumbar disc degeneration (P=0.011). Thus, the association of Trp2 with LDD was not replicated, but COL9A2 susceptibility allele(s) other than Trp2 may be present in Japanese LDD.

A new autosomal recessive form of Stickler syndrome is caused by a mutation in the COL9A1 gene

Stickler syndrome is characterized by ophthalmic, articular, orofacial, and auditory manifestations. It has an autosomal dominant inheritance pattern and is caused by mutations in COL2A1, COL11A1, and COL11A2. We describe a family of Moroccan origin that consists of four children with Stickler syndrome, six unaffected children, and two unaffected parents who are distant relatives (fifth degree). All family members were clinically investigated for ear, nose, and throat; ophthalmologic; and radiological abnormalities. Four children showed symptoms characteristic of Stickler syndrome, including moderate-to-severe sensorineural hearing loss, moderate-to-high myopia with vitreoretinopathy, and epiphyseal dysplasia. We considered the COL9A1 gene, located on chromosome 6q13, to be a candidate gene on the basis of the structural association with collagen types II and XI and because of the high expression in the human inner ear indicated by cDNA microarray. Mutation analysis of the coding region of the COL9A1 gene showed a homozygous R295X mutation in the four affected children. The parents and four unaffected children were heterozygous carriers of the R295X mutation. Two unaffected children were homozygous for the wild-type allele. None of the family members except the homozygous R295X carriers had any signs of Stickler syndrome. Therefore, COL9A1 is the fourth identified gene that can cause Stickler syndrome. In contrast to the three previously reported Stickler syndrome-causing genes, this gene causes a form of Stickler syndrome with an autosomal recessive inheritance pattern. This finding will have a major impact on the genetic counseling of patients with Stickler syndrome and on the understanding of the pathophysiology of collagens. Mutation analysis of this gene is recommended in patients with Stickler syndrome with possible autosomal recessive inheritance.

Characterization of an abundant COL9A1 transcript in the cochlea with a novel 3' UTR: Expression studies and detection of miRNA target sequence

EST N66408 represents one of several large unique clusters expressed in the Morton human fetal cochlear cDNA library. N66408 is 575 bp in size and initial BLAST analysis of this sequence showed no homology to any known genes or expressed sequence tags (ESTs) from other organs or tissues. Sequence of the original cochlear clone from which N66408 was derived revealed that the corresponding cDNA was about 700 bp in size, including 125 bp at its 5' end with homology to the 3' end of COL9A1 in addition to 575 bp of novel sequence. RT-PCR analysis using primers specific to COL9A1 isoforms 1 and 2 detected expression of both isoforms in human fetal cochlea. Tissue in situ hybridization using the novel 3' UTR sequence as probe showed abundant expression in spiral limbus and spiral ligament, and a moderate level of expression in the organ of Corti. dbEST analysis of ESTs specific to the 3' UTR of COL9A1 showed 19 ESTs derived from various tissues; three polyadenylation sites were identified and the majority of these ESTs were derived from overlapping polyadenylation signals at the second site (position 749-758). Comparison of the 3' UTR of human COL9A1 with its orthologs as well as with dbEST uncovered a highly conserved region around the overlapping polyadenylation signals at position 749-758 in mammals. A search of the microRNA database revealed a highly conserved target sequence for miR-9 immediately preceding the overlapping polyadenylation signals in the novel 3' UTR of COL9A1, suggesting its role in posttranscriptional regulation of COL9A1.

The alpha2 type IX collagen tryptophan polymorphism is associated with the severity of disc degeneration in younger patients with herniated nucleus pulposus of the lumbar spine

Tryptophan alleles in COL9A2 (Trp2) and COL9A3 (Trp3) have been linked to lumbar disc diseases in the Finnish population. Although such diseases consist of various pathogenetically different conditions, detailed analysis of each has not been well documented. The aim of this study was to clarify whether the collagen IX tryptophan alleles influence the symptomatic degeneration of the lumbar disc in Japanese patients with herniated nucleus pulposus. We performed a prospective study of 84 patients who underwent lumbar discectomy. The degree of disc degeneration was evaluated by magnetic resonance images in relation to the collagen IX genotype. Twenty patients (21.4%) had the Trp2 allele and no patients had the Trp3 allele. Patients under 40 years with the Trp2 allele showed more severe disc degeneration at the surgical level than did those without the Trp2 allele (odds ratio 6.00, P=0.043). In contrast, patients aged 40 years or over did not show significant association between disc degeneration and collagen IX genotype. Our results suggest that the Trp2 allele is an age-dependent risk factor for the severity of disc degeneration in younger patients with symptomatic herniated nucleus pulposus of the lumbar spine.

Intrafamilial phenotypic diversity in multiple epiphyseal dysplasia associated with a COL9A2 mutation (EDM2)

We describe a Japanese family with an autosomal dominant multiple epiphyseal dysplasia (MED EDM2) showing significant phenotypic diversity among the five affected members. Genomic analysis for COL9A2 identified an Ex3-1A>G heterozygous mutation, which has been proved to result in skipping of exon 3. The proband was a 9-year-old boy, who presented with ulnar club hands due to severe epiphyseal dysplasia in the distal ulnae. Radiological examination showed multiple epiphyseal dysplasias, predominantly involving the knee and the wrist. The hip appeared almost normal. The malalignment of the wrist was successfully treated with a limb lengthening procedure. The phenotype of the asymptomatic 12-year-old brother was similar to, but milder than, that of the proband. The asymptomatic 39-year-old mother, the 35-year-old uncle, and the 65-year-old grandmother with bilateral painful knees showed radiographically mild and severe osteoarthritis of the knee, respectively, and none of them had wrist deformity.

Comprehensive screening of multiple epiphyseal dysplasia mutations in Japanese population

Multiple epiphyseal dysplasia (MED) is among the most genetically heterogeneous skeletal dysplasias. Six genes involved in MED, COMP, MATN3, COL9A1, COL9A2, COL9A3, and DTDST have been identified; however, the presence of additional disease genes has been reported, and the detection rate for mutations in known genes accounts for no more than 50% of patients with MED in Western populations. Here, we screened the six known disease genes in 35 consecutive Japanese MED patients. We analyzed the entire coding region of each gene, along with flanking intron-exon junctions, by direct sequencing. A total of 19 mutations were identified in COMP, MATN3, COL9A2, COL9A3, and DTDST. The detection rate for known mutations was higher in this study than in previous reports, and we identified a substantially different spectrum of mutations. Mutations in MATN3 were more prevalent among these Japanese patients, whereas no DTDST mutations were detected. Most of the mutations were localized within specific regions of each gene: COMP mutations were found in the calmodulin-like repeat domains; MATN3 mutations in the von Willebrand factor type A domain; and type IX collagen gene mutations occurred in the third collagenous domains. Based on the integration of clinical and genetic information, we propose an algorithm for detecting mutations in Japanese MED patients. Our study further supports the existence of additional MED gene(s).

The TRP2 allele of COL9A2 is an age-dependent risk factor for the development and severity of intervertebral disc degeneration

STUDY DESIGN

Low back pain (LBP) and sciatica are usually caused by degenerative disc disease (DDD). Although they are common, the etiology of these conditions is poorly understood. A large population case-control study in the Southern Chinese was performed to study genetic risk factors to DDD.

OBJECTIVES

To gain a better understanding of the etiology of DDD in relation to structural defects of the intervertebral disc.

SUMMARY OF BACKGROUND DATA

A Finnish study found an association between LBP and sciatica with two variants of the alpha-chains of collagen IX, encoded by the Trp2 and Trp3 alleles, representing Gln326Trp and Arg103Trp amino acid substitutions in the COL9A2 and COL9A3 genes, respectively. Trp2 was found only in affected individuals (4%), whereas Trp3 was present in both affected (24%) and unaffected (9%) individuals. Because of the low frequency of the Trp2 allele in whites, the significance and contribution of this allele to DDD are not known. Using more objective criteria to define the disease by magnetic resonance imaging (MRI), we tested these alleles for association with DDD in a large population study.

METHODS

Lumbar DDD, the presence of anular tears, and disc and endplate herniations were defined by MRI in 804 Southern Chinese volunteers 18 to 55 years of age. These were correlated with the frequencies of the Trp2 and Trp3 alleles.

RESULTS

The Trp2 allele was present in 20% of the population and was associated with a fourfold increase in the risk of developing anular tears at 30 to 39 years and a 2.4-fold increase in the risk of developing DDD and endplate herniations at 40 to 49 years. Affected Trp2 individuals had more severe degeneration. The Trp3 allele was absent from the Southern Chinese population.

CONCLUSION

This largest-ever population study using MRI to define DDD demonstrates for the first time that the Trp2 allele is a significant risk factor for the development and severity of degeneration. The association is age- dependent as it is more prevalent in some age groups than in others. The contrasting Trp allele frequencies between the Finns and the Chinese are the first indication that the genetic risk factors for DDD varies between ethnic groups.

The alpha 2 type IX collagen gene tryptophan polymorphism is not associated with rheumatoid arthritis in the Japanese population

The aim of this study was to investigate whether the alpha 2 type IX collagen (COL9A2) polymorphism that introduces tryptophan residue into the collagen triple-helix is a marker of susceptibility to, or severity of, rheumatoid arthritis (RA). The study included 749 Japanese patients with RA. One hundred twenty-four unrelated healthy individuals served as the control subjects. The relationship between the COL9A2 gene polymorphism and clinical manifestations of RA was evaluated. For the number of subjects positive for COL9A2 tryptophan polymorphism, there was no statistically significant difference between RA patients and normal controls. Furthermore, we did not detect any association of COL9A2 tryptophan polymorphism with disease status, least erosive subset, more erosive subset, or mutilating disease. The lack of association of COL9A2 tryptophan polymorphism with RA and the clinical findings in our study implies that the polymorphism may not function as a candidate gene marker for screening RA patients.

Intervertebral disc degeneration in relation to the COL9A3 and the IL-1ss gene polymorphisms

Disc degeneration is a complex condition in which environmental factors and multiple genes are expected to act together to determine the degenerative phenotype. Recently associations of COL9A2 (Trp2 allele) and COL9A3 (Trp3 allele) polymorphisms with lumbar disc disease characterized by sciatica have been reported. However, it is not known whether the Trp2 or Trp3 alleles contribute to disc degeneration (DD). In this study, the association between the collagen genes polymorphisms and lumbar DD was investigated. Furthermore, the influence of the IL-1beta(C(3954)-T) polymorphism on the association of collagen genes polymorphisms with DD was examined. Lumbar intervertebral discs of 135 middle-aged occupationally active men were evaluated with magnetic resonance imaging, using decreased signal intensity of the nucleus pulposus, disc bulges, and decreased disc height as signs of degeneration. Blood samples were analysed for the presence of COL9A3 and COL9A2 tryptophan alleles (Trp3 and Trp2 alleles). The COL11A2, COL2A1 and IL-1beta(C(3954)-T) polymorphisms were also analysed. Multivariate logistic regression analysis allowing for occupation and body mass index showed that the carriage of the Trp3 allele in the absence of the IL-1betaT(3954) allele increased the risk of dark nucleus pulposus (OR 7.0, 95% CI 1.3-38.8) and joint occurrence of degenerative changes (OR 8.0, 95% CI 1.4-44.7). There was no effect of the Trp3 allele on DD in the presence of the IL-1betaT(3954) allele. The carriers of the COL11A2 minor allele had an increased risk of disc bulges (OR 2.1, 95% CI 1.0-4.2) as compared with non-carriers. The results suggest that the effect of the COL9A3 gene polymorphism on DD might be modified by the IL-1beta gene polymorphism.