The CALM1 core promoter polymorphism is not associated with hip osteoarthritis in a United Kingdom Caucasian population

Genome-Wide Association Study and Transcriptome of Japanese Patients with Developmental Dysplasia of the Hip Demonstrates an Association with the Ferroptosis Signaling Pathway

This study examined the association between developmental dysplasia of the hip (DDH) and disease-associated loci in a Japanese cohort. A genome-wide association study (GWAS) of 238 Japanese patients with DDH and 2044 healthy individuals was performed. As a replicate, GWAS was also conducted on the UK Biobank data with 3315 cases and matched 74,038 controls. Gene set enrichment analyses (GSEAs) of both the genetics and transcriptome of DDH were performed. Transcriptome analysis of cartilage specimens from DDH-associated osteoarthritis and femoral neck fractures was performed as a control. Most of the lead variants were very low-frequency ones in the UK, and variants in the Japanese GWAS could not be replicated with the UK GWAS. We assigned DDH-related candidate variants to 42 and 81 genes from the Japanese and UK GWASs, respectively, using functional mapping and annotation. GSEA of gene ontology, disease ontology, and canonical pathways identified the most enriched pathway to be the ferroptosis signaling pathway, both in the Japanese gene set as well as the Japanese and UK merged set. Transcriptome GSEA also identified significant downregulation of genes in the ferroptosis signaling pathway. Thus, the ferroptosis signaling pathway may be associated with the pathogenic mechanism of DDH.

Genetic markers of osteoarthritis: early diagnosis in susceptible Pakistani population

Background and aim

Osteoarthritis (OA) is a multiple factorial disease with unidentified specific markers. The alternate method such as biochemical and genetic markers for the diagnosis of osteoarthritis is an undeniable need of the current era. In the present study, we aimed to investigate the association of interleukin-6 (IL-6)(IL-6-174G/C), transforming growth factor-β1 (TGF-beta1-29C/T), and calmodulin 1 gene-16C/T (CALM1-16C/T) polymorphism in clinically definite Pakistani OA patients and matching controls.

Methods

The study design was based on biochemical analysis of OA via serum hyaluronic acid (HA) enzyme-linked immunosorbent assay (ELISA) test and genetic analysis based on amplification refractory mutation system (ARMS) PCR. Statistical evaluations of allele probabilities were carried through chi-squared test. This study includes 295 subjects including 100 OA patients, 105 OA susceptible, and 90 controls.

Results

HA levels obtained were distinct for all the populations: patients with a mean value of ± 5.15, susceptible with mean value of ± 2.27, and control with mean value of ± 0.50. The prevalent genotypes in OA were GG genotype for IL-6-174G/C, CT genotypes for TGF β1-29C/T, and TT genotype for CALM1-16C/T polymorphism. A significant P value of 0.0152 is obtained as a result of the comparison among the patients and controls on the number of individuals possessing the disease-associated genotypes.

Conclusions

The positive association of GG genotype for IL-6-174G/C, TT genotype for CALM1-16C/T polymorphism in OA while high prevalence of CT TGF β1-29 C/T genotypes in susceptible population in our study group implies these polymorphisms can serve as susceptible marker to OA and genetic factors for screening OA patients in Pakistan. There might be other factors that may influence disease susceptibility. However, further investigations on larger population are required to determine the consequences of genetic variations for prediagnosis of OA.

Gene polymorphisms in calcium-calmodulin pathway: Focus on cardiovascular disease

Cardiovascular disease is the leading cause of death in industrialized countries and affects an increasing number of people. Several risk factors play an important role in the etiology of this disease, such as an unhealthy lifestyle. It is increasingly clear that genetic factors influencing the molecular basis of excitation-contraction mechanisms in the heart could contribute to modify the individual's risk. Thanks to the progress that has been made in understanding calcium signaling in the heart, it is assumed that calmodulin can play a crucial role in the excitation-contraction coupling. In fact, calmodulin (CaM) binds calcium and consequently regulates calcium channels. Several works show how some polymorphic variants can be considered predisposing factors to complex pathologies. Therefore, we hypothesize that the identification of polymorphic variants of proteins involved in the CaM pathway could be important for understanding how genetic traits can influence predisposition to myocardial infarction. This review considers each pathway of the three different isoforms of calmodulin (CaM1; CaM2; CaM3) and focuses on some common proteins involved in the three pathways, with the aim of analyzing the polymorphisms studied in the literature and understanding if they are associated with cardiovascular disease.

Genetics in Cartilage Lesions: Basic Science and Therapy Approaches

Cartilage lesions have a multifactorial nature, and genetic factors are their strongest determinants. As biochemical and genetic studies have dramatically progressed over the past decade, the molecular basis of cartilage pathologies has become clearer. Several homeostasis abnormalities within cartilaginous tissue have been found, including various structural changes, differential gene expression patterns, as well as altered epigenetic regulation. However, the efficient treatment of cartilage pathologies represents a substantial challenge. Understanding the complex genetic background pertaining to cartilage pathologies is useful primarily in the context of seeking new pathways leading to disease progression as well as in developing new targeted therapies. A technology utilizing gene transfer to deliver therapeutic genes to the site of injury is quickly becoming an emerging approach in cartilage renewal. The goal of this work is to provide an overview of the genetic basis of chondral lesions and the different approaches of the most recent systems exploiting therapeutic gene transfer in cartilage repair. The integration of tissue engineering with viral gene vectors is a novel and active area of research. However, despite promising preclinical data, this therapeutic concept needs to be supported by the growing body of clinical trials.

Association between the polymorphisms of CALM1 gene and osteoarthritis risk: a meta-analysis based on observational studies

The existing studies on the association between polymorphisms of Calmodulin 1 (CALM1) gene and the risk of osteoarthritis (OA, a complex multifactorial disease and a major degenerative form of arthritis) in different populations have yielded conflicting findings. Therefore, we conducted a meta-analysis by systematically searching PubMed, Embase, Medline, Cochrane Library and Google Scholar, and assessing this association by calculating pooled odds ratios with 95% confidence intervals. Subgroup analyses stratified by ethnicity, OA type, and genotype were also conducted. Six studies (2752 cases and 3259 controls) involving six single nucleotide polymorphisms were included. Our data suggested that the T allele and genotype TT of the rs12885713 polymorphism, and the C allele of the rs2300496 polymorphism in the CALM1 gene all increased the risk of OA. The pooled results revealed no significant association between the CALM1 rs3213718 polymorphism and the risk of OA. Stratification analyses by ethnicity and OA type showed that the rs12885713 polymorphism increased the risk of OA among Asians and in knee OA, respectively. In conclusion, the rs12885713 and rs2300496 polymorphisms of the CALM1 gene may both increase the risk of OA. Owing to the limitations of the present study, this finding should be further confirmed in future well-designed studies.

The association between rs12885713 polymorphism in CALM1 and risk of osteoarthritis: A meta-analysis of case-control studies

OBJECTIVE

The single nucleotide polymorphism (SNP) rs12885713 of calmodulin 1 gene (CALM1) has been reported to involve in the etiology of osteoarthritis (OA) in several association studies with limited sample size and conflicting results. The purpose of the present systematic review and meta-analysis was to evaluate and synthesize the currently available data on the correlation between rs12885713 and OA susceptibility.

METHODS

Six electronic databases including PubMed, EMBASE, ISI Web of Science, CNETRAL, CNKI, and Wanfang were systematically retrieved to identify relevant observational articles published before October 2017. Summary odds ratios (ORs) and corresponding 95% confidence intervals (95% CIs) were calculated to indicate the association between CALM1 polymorphism and OA. Risk of bias was assessed through the Newcastle-Ottawa Scale. Predetermined subgroups and sensitivity analyses were performed using the RevMan 5.3 software. Publication bias was evaluated by Egger and Begg tests.

RESULTS

Overall, 5 case-control studies involving 2183 OA patients 2654 healthy control subjects satisfied the meta-analysis. Recessive model was confirmed to be the best-matching genetic model (TT + TC versus CC). The pooled outcomes indicated that rs12885713 SNP was not significantly associated with OA vulnerability (OR 1.11, 95% CI 0.97, 1.27; P = .12). When stratified by different genders, OA sites, and population descents respectively, still non-significant associations were found.

CONCLUSION

Based on the findings of our present study, the rs12885713 polymorphism of CALM1 did not appear to be associated with OA predisposition.

Functional polymorphisms in asporin and CILP together with joint loading predispose to hand osteoarthritis

Background

Osteoarthritis (OA) is the most common degenerative joint disease afflicting people in the Western world and has a strong genetic influence. The aim of this study was to examine the association of two known functional polymorphisms in the TGF-β inhibiting genes, asporin (ASPN) and cartilage intermediate layer protein (CILP), with hand OA and potential gene-occupational hand loading interaction.

Results

Statistically significant interaction of the CILP rs2073711 T and ASPN D15 alleles with hand OA was observed (OR = 2.48, 95% CI 1.27–4.85, p = 0.008) in a Finnish hand OA cohort of 543 women (aged 45–63). When stratified by variation in working tasks, low variation of working tasks increased the risk further (OR = 3.00, 95% CI 1.35–6.66, p = 0.007). Based on the analysis of ASPN and CILP protein-coding regions, functional studies were performed with one observed variant, rs41278695 in the ASPN gene. Analyses showed that bone morphogenetic protein 2 (BMP2) mediated expression of aggrecan (Agc1) and type II collagen (Col2a1) was significantly suppressed (p = 0.011 and p = 0.023, respectively) in a murine chondrocytic cell line (ATDC5) with cells stably expressing ASPN rs41278695.

Conclusions

The carriage of either ASPN D15 or CILP rs2073711 TT is associated with increased risk of symmetrical hand OA, particularly in individuals with low variation in work tasks. ASPN rs41278695 SNP had an effect on Agc1 and Col2a1 gene expression when induced with BMP-2 suggesting an effect on the cartilage extracellular matrix composition.

Expression of Genes and Their Polymorphism Influences the Risk of Knee Osteoarthritis

Introduction

Genetic factors including the level of expression of the fingerprint of genes involved in the development of bones and cartilage such as GDF-5 or ESR-α or CALM-1 are known to be strong determinants of the osteoarthritis (OA) in Caucasian and Oriental populations. Because of high prevalence of OA in Indian population and availability of limited genetic data, we determined whether similar genetic factors are involved in Indians as well.

Methods

A case control study was carried out involving 500 patients of knee OA and equal number of healthy controls. Genotyping analyses in whole blood, mRNA, and protein expressions in peripheral blood lymphocytes (PBLs) were performed using established protocols.

Results

Our results showed a significantly decreased level of mRNA and protein expressions for GDF-5, ESR-α, and CALM-1 genes in PBLs of OA cases when compared to healthy controls. The frequency of variant genotypes of these genes was also increased significantly in cases of OA compared to controls.

Conclusion

Our results demonstrated that the decrease in expression of GDF-5, ESR-α, and CALM-1 in PBLs and association of polymorphism in these genes may be important in predicting the severity and thereby the progression of OA in Indian population.

The genetics behind osteoarthritis: Asian focus

Osteoarthritis (OA), a degenerative joint disease, is the most common form of arthritis in the elderly. Problems arising from the condition are not only health, physical, and psychological, but also economical and social. OA is a complex disease causes by environmental factors (obesity, female gender, advancing age) and genetics. A strong genetic contribution to primary OA has been observed in several studies. Asian population is undoubtedly genetically different from European, whom most studies have been performed. This review systematically compares results of molecules involved with OA from studies performed on Asian and Caucasian populations. The clear differences between Asian and Caucasian populations may be from the sex- and ethnic-specific nature of the disease, as well as from the inclusion criteria of the studies. Global collaboration is highly significant in understanding genetic underlying OA. Knowledge gained from genetic study is important to the development of prevention and therapeutic intervention, and to identify individuals at risk of developing severe or progressive OA.

New challenges and promises in solid organ transplantation pharmacogenetics: the genetic variability of proteins involved in the pharmacodynamics of immunosuppressive drugs

Interindividual variability in immunosuppressive drug responses might be partly explained by genetic variants in proteins involved in the immune response or associated with IS pharmacodynamics. On a general basis, the pharmacogenetics of drug target proteins is less known and understood than that of proteins involved in drug disposition pathways. The aim of this review is to facilitate research related to the pharmacodynamics of the main immunosuppressive drugs used in solid organ transplantation. We elaborated a quality of evidence grading system based on a literature review and identified 'highly recommended', 'recommended' or 'potential' candidates for further research. It is likely that a number of additional rare variants might further explain drug response phenotypes in transplantation, and particularly the most severe ones. The advent of next-generation sequencing will help to identify those variants.

Genetic susceptibility of lumbar degenerative disc disease in young Indian adults

PURPOSE

Although the exact mechanisms that lead to degenerative disc disease (DDD) are not well understood, a significant genetic influence has been found. Focusing on DDD that occurs in young adults can be valuable in determining the exact role of genetic predisposition to DDD.

METHODS

Patients (<40 years) with lumbar disc degeneration were evaluated with MRI imaging (1.5 Tesla) and genetic association analysis for 58 single nucleotide polymorphism (SNP) of 35 candidate genes was performed. Disc degeneration of individual discs of lumbar spine from L1 to S1 was graded by Pfirrmann's grading. The subjects were stratified into two groups based on Total Disc Degenerative Score (TDDS). Based on TDDS, the severity of DDD was classified as mild (Group A: TDDS <10) and severe (Group B: TDDS >10).

RESULTS

695 Indian subjects including 308 with mild TDDS and 387 with severe TDDS were studied. The mean age of the patients was 29.6 ± 6.9 years in group A and 31.7 ± 6.1 in group B (p < 0.05). Five of the 35 candidate genes viz., rs1337185 of COL11A (p = 0.02), rs5275 (p = 0.03) and rs5277 (p = 0.05) of COX2, rs7575934 of IL1F5 (p = 0.04), rs3213718 of CALM1 (p = 0.04) and rs162509 of ADAMTS5 (p = 0.04) were found to be significantly associated with severe TDDS.

CONCLUSION

The study identifies specific SNP associations of five genes in young adults with severe lumbar disc degeneration. These five genes (COL11A1, ADAMTS5, CALM1, IL1F5 and COX2) have different functions in the matrix metabolism, intracellular signalling and inflammatory cascade. This shows that disc degeneration is a complex disease with an intricate interplay of multiple genetic polymorphisms.

The genetics and functional analysis of primary osteoarthritis susceptibility

Recent genome-wide association scans (GWASs) along with several adequately powered candidate gene studies have yielded a number of risk alleles for osteoarthritis (OA). This number is now sufficiently large to allow conclusions to be drawn regarding the nature of genetic susceptibility, including the fact that the risk alleles have variable effects depending on sex, ethnicity and on the skeletal site of the disease. Several of the alleles that have emerged from the GWASs are within or close to highly plausible candidate genes, including RUNX2 and CHST11. However, the majority of risk alleles do not map to genes previously reported to play a role in musculoskeletal biology, indicating that the GWAS datasets are telling us something new about the OA disease process. Functional studies have so far revealed that effects on gene expression are likely to be one of the main mechanisms through which OA susceptibility is acting. Epigenetic mechanisms such as DNA methylation also influence OA risk, and integration of genetic, transcriptomic and epigenetic data will allow us to use the genetic discoveries for informed development of new OA biological treatments.

Relationship between joint shape and the development of osteoarthritis

PURPOSE OF REVIEW

To present an updated summary of the relationship between joint shape and the development of osteoarthritis, with a particular focus on osteoarthritis of the hip.

RECENT FINDINGS

Osteoarthritis of the hip is highly heritable, with a genetic contribution estimated at 60%. Among the genes that have been linked to this disease are several that are involved in the development and maintenance of joint shape, including members of the Wingless (Wnt) and the bone morphogenetic protein (BMP) family. Several features of hip joint architecture, such as acetabular dysplasia, pistol grip deformity, wide femoral neck, altered femoral neck-shaft angle, appear to play an important role in the pathogenesis of osteoarthritis and may predate the development of osteoarthritis by decades.

SUMMARY

Gene-environment interactions play a crucial role in the development of osteoarthritis. The architecture of joint shape is determined by a complex sequence spanning embryonic, childhood, and adult life and contributes to the pathogenesis of osteoarthritis.

The Otto Aufranc Award: Identification of a 4 Mb region on chromosome 17q21 linked to developmental dysplasia of the hip in one 18-member, multigeneration family

Developmental dysplasia of the hip (DDH) is a disabling condition that, depending on geography, can afflict between 20% and 80% of patients with end-stage arthritis of the hip. Despite its prevalence, the etiology of this disease remains unknown. DDH is a complex disorder with both environmental and genetic causes. Based on the literature the candidate genes for the disease are HOXB9, collagen type I alpha1, and DLX 3. The purpose of our study was to map and characterize the gene or genes responsible for this disorder by family linkage analysis. We recruited one 18-member, multigeneration affected family to provide cheek swabs and blood samples for isolation of DNA. Amplified DNA underwent a total genome scan using GeneChip Mapping 250 K Assay (Affymetrix, Santa Clara, CA). We observed only one region with a LOD score greater than 1.5: a 4 Mb region on chromosome 17q21.32, yielding a LOD score of 1.82. While a LOD score of 1.82 does not meet the accepted standard for linkage we interpret these data as suggesting the responsible gene could be linked to this region, which includes a cluster of homeobox genes (HOX genes) that are part of the developmental regulatory system providing cells with specific positional identities along the developing joint and spine. Discovering the genetic basis of the disease would be an important step in understanding the etiology of this disabling condition.

Rare variants create synthetic genome-wide associations

A large number of different common variants has been associated with very modest increases of risk for various common diseases. A simulation study shows that rare variants with much greater impacts on disease risk may be responsible for some of these associations.

Genome-wide association studies (GWAS) have now identified at least 2,000 common variants that appear associated with common diseases or related traits (http://www.genome.gov/gwastudies), hundreds of which have been convincingly replicated. It is generally thought that the associated markers reflect the effect of a nearby common (minor allele frequency >0.05) causal site, which is associated with the marker, leading to extensive resequencing efforts to find causal sites. We propose as an alternative explanation that variants much less common than the associated one may create “synthetic associations” by occurring, stochastically, more often in association with one of the alleles at the common site versus the other allele. Although synthetic associations are an obvious theoretical possibility, they have never been systematically explored as a possible explanation for GWAS findings. Here, we use simple computer simulations to show the conditions under which such synthetic associations will arise and how they may be recognized. We show that they are not only possible, but inevitable, and that under simple but reasonable genetic models, they are likely to account for or contribute to many of the recently identified signals reported in genome-wide association studies. We also illustrate the behavior of synthetic associations in real datasets by showing that rare causal mutations responsible for both hearing loss and sickle cell anemia create genome-wide significant synthetic associations, in the latter case extending over a 2.5-Mb interval encompassing scores of “blocks” of associated variants. In conclusion, uncommon or rare genetic variants can easily create synthetic associations that are credited to common variants, and this possibility requires careful consideration in the interpretation and follow up of GWAS signals.

It has long been assumed that common genetic variants of modest effect make an important contribution to common human diseases, such as most forms of cardiovascular disease, asthma, and neuropsychiatric disease. Genome-wide scans evaluating the role of common variation have now been completed for all common disease using technology that claims to capture greater than 90% of common variants in major human populations. Surprisingly, the proportion of variation explained by common variation appears to be very modest, and moreover, there are very few examples of the actual variant being identified. At the same time, rare variants have been found with very large effects. Now it is demonstrated in a simulation study that even those signals that have been detected for common variants could, in principle, come from the effect of rare ones. This has important implications for our understanding of the genetic architecture of human disease and in the design of future studies to detect causal genetic variants.

Recent advances in association studies of osteoarthritis susceptibility genes

Osteoarthritis (OA) is a polygenic disease with a definite genetic component, and recent advances in genome research have enabled us to investigate OA susceptibility genes. Several research groups, including ours, have reported the identification of OA susceptibility genes, mainly using candidate gene association studies. However, we are now entering the era of genome-wide association studies (GWAS). Here, we review recent progress in the study of susceptibility genes for OA, focusing in particular on GWAS and large-scale replication studies.

Osteoarthritis

Osteoarthritis (OA) is a chronic degenerative disorder characterized by cartilage loss. Its prevalence is high, and it is a major cause of disability. The cause of OA is not known; however, current evidence indicates that it is multifactorial. Major risk factors for osteoarthritis are age, female sex, obesity, geographic factors, occupational knee-bending, physical labour, genetic factors and race, joint trauma, vitamin D deficiency, and chondrocalcinosis. Osteoarthritis causes joint pain, stiffness, and limitation of joint function. Knee involvement is the commonest presentation of this disease all over the world. Given the absence of a curative treatment, it is important to treat osteoarthritis as effectively as possible using a multidisciplinary approach tailored to the patient's needs. This article reviews current thinking on the epidemiology, clinical presentation, lifestyle, genetic epidemiology, and management of osteoarthritis in developing countries.

The contribution of genes to osteoarthritis

Osteoarthritis (OA) is the most prevalent form of arthritis in the elderly. A large body of evidence, including familial aggregation and classic twin studies, indicates that primary OA has a strong hereditary component that is likely polygenic in nature. Traits related to OA, such as longitudinal changes in cartilage volume and progression of radiographic features, are also under genetic control. In recent years several linkage analyses and candidate gene studies have been performed and unveiled some of the specific genes involved in disease risk, such as FRZB and GDF5. This article discusses the impact that future genome-wide association scans can have on our understanding of the pathogenesis of OA and on identifying individuals at high risk for developing severe OA.

Low rate of total hip replacement as reflected by a low prevalence of hip osteoarthritis in South Korea

OBJECTIVE

We attempted to estimate the rate of total hip replacement (THR) using a national database and the prevalence of hip osteoarthritis (OA) from the reading of intravenous pyelograms (IVPs) in a Korean population.

MATERIALS

Reimbursement records from all hospitals in South Korea were extracted from the Health Insurance Review Agency (HIRA) database. Records with both the procedure code corresponding to THR and containing the diagnosis code for hip OA were selected. We estimated the age- and sex-specific rates of THR from 2002 to 2006. Hip joints from 580 subjects older than 70 years old who underwent an IVP were assessed for the presence of OA.

RESULTS

The rate of THR increased with age, reaching a peak over the age of 65-69 years, with the age-standardized risk ratios in women vs men of approximately 1.5. Although the rate of THR increased over the 5-year study period, it was significantly lower than that of total knee replacement (TKR) in Korean population (THR vs TKR 1:15.9). The prevalence of hip OA in the IVP cohort was 1.2% (1.7% for men and 0.7% for women).

CONCLUSION

The rate of THR was significantly lower than that of TKR in Korean population. Hip OA prevalence among the IVP subjects was 1.2%. Further studies on factors that account for the low prevalence of hip OA among Asians need to be conducted.

Lack of association between the CALM1 core promoter polymorphism (-16C/T) and susceptibility to knee osteoarthritis in a Chinese Han population

BACKGROUND

CALM1 gene encodes calmodulin (CaM), an important and ubiquitous eukaryotic Ca2+-binding protein. Several studies have indicated that a deficient CaM function is likely to be involved in the pathogenesis of osteoarthritis (OA). Using a convincing genome-wide association study, a Japanese group has recently demonstrated a genetic association between the CALM1 core promoter polymorphism (-16C/T transition SNP, rs12885713) and OA susceptibility. However, the subsequent association studies failed to provide consistent results in OA patients of differently selected populations. The present study is to evaluate the association of the -16C/T polymorphism with knee OA in a Chinese Han population.

METHODS

A case-control association study was conducted. The polymorphism was genotyped in 183 patients who had primary symptomatic knee OA with radiographic confirmation and in 210 matched controls. Allelic and genotypic frequencies were compared between patients and control subjects.

RESULTS

No significant difference was detected in genotype or allele distribution between knee OA and control groups (all P > 0.05). The association was also negative even after stratification by sex. Furthermore, no association between the -16C/T SNP genotype and the clinical variables age, sex, BMI (body mass index) and K/L (Kellgren/Lawrence) score was observed in OA patients.

CONCLUSION

The present study suggests that the CALM1 core promoter polymorphism -16C/T is not a risk factor for knee OA susceptibility in the Chinese Han population. Further studies are needed to give a global view of this polymorphism in pathogenesis of OA.

The contribution of genes to osteoarthritis

Osteoarthritis (OA) is the most prevalent form of arthritis in the elderly. A large body of evidence, including familial aggregation and classic twin studies, indicates that primary OA has a strong hereditary component that is likely polygenic in nature. Furthermore, traits related to OA, such as longitudinal changes in cartilage volume and progression of radiographic features, are also under genetic control. In recent years, several linkage analysis and candidate gene studies have been performed and have unveiled some of the specific genes involved in disease risk, such as FRZB and GDF5. The authors discuss the impact that future genome-wide association scans can have on our understanding of the pathogenesis of OA and on identifying individuals at high risk for developing severe OA.

Association of the CALM1 core promoter polymorphism with knee osteoarthritis in patients of Greek origin

PURPOSE

Osteoarthritis (OA) is characterized by focal areas of loss of articular cartilage in synovial joints, associated with varying degrees of osteophyte formation, subchondral bone change, and synovitis. The Calmodulin 1 gene (CALM1) encodes for a ubiquitous eukaryotic Ca2+ binding protein and is the principal mediator of the calcium signal. The protein thus affects the chondrocyte's response to mechanical load. A functional core promoter single nucleotide polymorphism (SNP) -16C/T (rs12885713) was recently associated with hip OA (HOA) in the Japanese population, while no association was found in a British group of patients with HOA. Our objective was to assess whether this SNP was also associated with knee OA (KOA) in a Greek Caucasian population sample.

METHODS

The -16T/C SNP was genotyped in a 351 case-control cohort--158 patients with idiopathic KOA and 193 controls.

RESULTS

No significant differences were found in genotype frequencies for the -16T/C SNP of CALM1 gene between cases and controls (p = 0.581).

CONCLUSION

Our data implied that the -16TT (rs12885713) CALM1 core promoter genotype is not a risk factor for OA etiology in Greek Caucasians on its own, but associated with the Asporin (ASPN) D14 or D15 risk allele, it could influence KOA susceptibility.

Genome-wide association scan identifies a prostaglandin-endoperoxide synthase 2 variant involved in risk of knee osteoarthritis

Osteoarthritis (OA), the most prevalent form of arthritis in the elderly, is characterized by the degradation of articular cartilage and has a strong genetic component. Our aim was to identify genetic variants involved in risk of knee OA in women. A pooled genome-wide association scan with the Illumina550 Duo array was performed in 255 controls and 387 cases. Twenty-eight variants with p < 1 x 10(-5) were estimated to have probabilities of being false positives <or=0.5 and were genotyped individually in the original samples and in replication cohorts from the UK and the U.S. (599 and 272 cases, 1530 and 258 controls, respectively). The top seven associations were subsequently tested in samples from the Netherlands (306 cases and 584 controls). rs4140564 on chromosome 1 mapping 5' to both the PTGS2 and PLA2G4A genes was associated with risk of knee OA in all the cohorts studied (overall odds ratio OR(mh) = 1.55 95% C.I. 1.30-1.85, p < 6.9 x 10(-7)). Differential allelic expression analysis of PTGS2 with mRNA extracted from the cartilage of joint-replacement surgery OA patients revealed a significant difference in allelic expression (p < 1.0 x 10(-6)). These results suggest the existence of cis-acting regulatory polymorphisms that are in, or near to, PTGS2 and in modest linkage disequilibrium with rs4140564. Our results and previous studies on the role of the cyclooxygenase 2 enzyme encoded by PTGS2 underscore the importance of this signaling pathway in the pathogenesis of knee OA.

Association of single-nucleotide polymorphisms in RHOB and TXNDC3 with knee osteoarthritis susceptibility: two case-control studies in East Asian populations and a meta-analysis

Introduction

Conflicting findings on the association of single nucleotide polymorphisms (SNPs) in RHOB and TXNDC3 with susceptibility to knee osteoarthritis (OA) have been reported in European Caucasians. To examine the associations of these SNPs with OA in East Asian populations and to evaluate their global significance, we conducted two case-control studies in 955 Chinese and 750 Japanese patients.

Methods

We genotyped the previously implicated SNPs rs585017 (in RHOB) and rs4720262 (in TXNDC3) in patients with primary symptomatic knee OA with radiographic confirmation and in matched control individuals, and analyzed their associations. We further conducted a meta-analysis of the study findings together with those of previously reported European studies using the DerSimonian-Laird procedure.

Results

A significant association of RHOB with knee OA was observed in male Chinese patients (P = 0.02). No significant associations were found for RHOB in any other comparisons in the East Asian populations. The association of TXNDC3 was replicated in Chinese female (P = 0.04) and Japanese (P = 0.03) patients, although none of these associations persisted after Bonferroni correction. Significant association (P = 0.02 for the allelic frequency) with nonsignificant heterogeneity was found in the East Asian replication study. No significant association was found in any comparison in the meta-analysis for all studies.

Conclusion

Our study replicates the association, previously reported in European Caucasians, of TXNDC3 with knee OA susceptibility in an East Asian population.

The growth differentiation factor 5 (GDF5) core promoter polymorphism is not associated with knee osteoarthritis in the Greek population

Genetic factors have been shown to play an important role in the etiology of osteoarthritis (OA). A functional single nucleotide polymorphism (SNP) +104T/C; rs143383 in the 5' UTR of the GDF5 gene was recently associated with susceptibility to osteoarthritis in the Japanese and Chinese population. Our objective was to assess whether this SNP was also associated with knee OA in a Greek Caucasian population sample. The +104T/C SNP was genotyped in a total of 519 case-control cohort; 251 patients with idiopathic knee OA and 268 controls were used. No significant differences were found in genotype or allele frequencies of the +104T/C SNP of GDF5 gene between cases and controls (p < 0.05). Also, no significant differences in allelic and genotypic frequencies were found when the individuals were stratified by sex. Our data implied that the +104T/C; rs143383 GDF5 core promoter polymorphism is not a risk factor for OA etiology in Greek Caucasians. Our study highlights the heterogeneous nature of OA genetic susceptibility.

An SNP in the 5′-UTR of GDF5 is associated with osteoarthritis susceptibility in Europeans and with in vivo differences in allelic expression in articular cartilage

A compelling genetic association with osteoarthritis (OA) of a functional SNP (rs143383, T/C) in the 5'-UTR of the GDF5 gene was recently reported in case-control cohorts from Japan and China. GDF5 is a pro-chondrogenic growth factor. The T-allele frequency of the gene was elevated in cases, with an odds ratio (OR) of 1.79, and in vitro functional studies demonstrated that this allele mediated a moderate but significant reduction in the activity of the GDF5 promoter in several cell lines. Our initial objective was to assess whether the SNP was also associated with OA in a broad European population by genotyping the SNP in 2487 cases and 2018 age-matched controls from the UK and Spain. The T-allele was associated with OA (P = 0.03, OR = 1.10) as was carrier status for this allele (P = 0.004, OR = 1.28), demonstrating that the SNP is associated with OA in two diverse ethnic groups, Asians and Europeans. We subsequently assessed the functional effect of the SNP on GDF5 allelic expression using RNA extracted from the cartilage of OA patients who had undergone joint-replacement surgery. The associated T-allele showed up to a 27% reduction in expression relative to the C-allele (P = 0.00007), revealing that the functional effect mediated by SNP rs143383 on GDF5 expression is active in patients who have severe disease up to the point at which they require surgery. A small but persistent imbalance of GDF5 expression throughout life therefore appears to render an individual more susceptible to OA.

Strong linkage on 2q33.3 to familial early-onset generalized osteoarthritis and a consideration of two positional candidate genes

A genomewide screen was performed in four extended families with early-onset generalized osteoarthritis (FOA) without dysplasia. The FOA phenotype within these families shows a dominant Mendelian inheritance pattern and may represent common osteoarthritis (OA) at later ages. An initial locus was confirmed by three additional families and refined by 14 markers to a two-point logarithm of odds score of 6.05 (theta=0.00) for marker D2S155 at chromosome 2q33.3. This locus coincided with the highest multipoint nonparametric linkage score of 4.70 (P-value=0.0013) at marker D2S2358. Haplotype analysis of family members delineated a narrow region with a number of possible positional candidates, of which we investigate here the two most likely ones: PTHR2, encoding parathyroid hormone receptor 2, and FZD5, encoding frizzled receptor 5. For FZD5, we did not observe a segregating variant, however, for PTHR2, a missense variant (A225S) cosegregated with FOA in one family. The frequency of the PTHR2 variant was rare in a population-based sample, aged 55-70 years (N=1228, 0.4%). Of the 11 carriers, 36% showed generalized radiographic OA as compared to 23% in the remaining population. None of the other families that contributed to the linkage revealed a segregating variant. Together, we have identified a locus on chromosome 2q33.3 for FOA. Candidate gene analysis suggested a possible association of a PTHR2 variant with generalized radiographic OA; it is, however, unlikely the major disease gene for the observed linkage to the FOA phenotype.

Sex and ethnic differences in the association ofASPN,CALM1,COL2A1,COMP, andFRZB with genetic susceptibility to osteoarthritis of the knee

OBJECTIVE

To assess whether the association of genetic polymorphisms with osteoarthritis (OA) in other populations could be replicated in a large, multicenter, mixed-sex, case-control study of clinical knee OA.

METHODS

Genetic polymorphisms in OA candidate genes were genotyped in 298 men and 305 women, ages 50-86 years, all of whom had a diagnosis of knee OA as assessed clinically and radiographically, and in 300 male and 299 female control subjects matched for age and ethnicity. Allele and haplotype frequencies for 5 genes (ASPN, CALM1, COL2A1, COMP, and FRZB) previously tested for association with hip and/or knee OA in other populations were compared between patients and control subjects, analyzing men and women separately.

RESULTS

The same FRZB 2-marker single-nucleotide polymorphism (SNP) haplotype associated with hip OA in other populations of Caucasian women was shown to increase the risk of knee OA among the women (but not the men) in the current study (odds ratio [OR] 2.87, P < 0.04). The CALM1 SNP, which affects the risk of hip OA in Japanese individuals, was not shown to be associated with susceptibility to OA in men or women. COL2A1 haplotypes were demonstrated to be associated with a decreased risk of knee OA in men (OR 0.68, P < 0.005) but not in women. COMP haplotypes that were associated with susceptibility to knee OA were different in men and women (P < 0.014 and P < 0.032, respectively). A meta-analysis of these data and those from previously published reports indicated a strong association between the FRZB G324 allele (P < 0.0003) and suggested that an ASPN allele is protective against the risk of knee OA in Caucasians (P < 0.02).

CONCLUSION

Our results indicate that genetic polymorphisms affecting knee OA vary between populations (Japanese versus Caucasian) and sexes and indicate a role for ASPN, COMP, FRZB, and COL2A1 in Caucasians.