Association of a single nucleotide polymorphism in pregnancy-associated plasma protein-A2 with developmental dysplasia of the hip: a case-control study

Developmental dysplasia of the hip: A systematic review of susceptibility genes and epigenetics

BACKGROUND

Developmental dysplasia of the hip (DDH) is a complex developmental deformity whose pathogenesis and susceptibility-related genes have yet to be elucidated. This systematic review summarizes the current literature on DDH-related gene mutations, animal model experiments, and epigenetic changes in DDH.

METHODS

We performed a comprehensive search of relevant documents in the Medline, Scopus, Cochrane, and ScienceDirect databases covering the period from October 1991 to October 2021. We analyzed basic information on the included studies and summarized the DDH-related mutation sites, animal model experiments, and epigenetic changes associated with DDH.

RESULTS

A total of 63 studies were included in the analysis, of which 54 dealt with the detection of gene mutations, 7 presented details of animal experiments, and 6 were epigenetic studies. No genetic mutations were clearly related to the pathogenesis of DDH, including the most frequently studied genes on chromosomes 1, 17, and 20. Most gene-related studies were performed in Han Chinese or North American populations, and the quality of these studies was medium or low. GDF5 was examined in the greatest number of studies, and mutation sites with odds ratios > 10 were located on chromosomes 3, 9, and 13. Six mutations were found in animal experiments (i.e., CX3CR1, GDF5, PAPPA2, TENM3, UFSP2, and WISP3). Epigenetics research on DDH has focused on GDF5 promoter methylation, three microRNAs (miRNAs), and long noncoding RNAs. In addition, there was also a genetic test for miRNA and mRNA sequencing.

CONCLUSIONS

DDH is a complex joint deformity with a considerable genetic component whose early diagnosis is significant for preventing disease. At present, no genes clearly involved in the pathogenesis of DDH have been identified. Research on mutations associated with this condition is progressing in the direction of in vivo experiments in animal models to identify DDH susceptibility genes and epigenetics analyses to provide novel insights into its pathogenesis. In the future, genetic profiling may improve matters.

Whole exome sequencing of 28 families of Danish descent reveals novel candidate genes and pathways in developmental dysplasia of the hip

Developmental dysplasia of the hip (DDH) is a common condition involving instability of the hip with multifactorial etiology. Early diagnosis and treatment are critical as undetected DDH is an important cause of long-term hip complications. Better diagnostics may be achieved through genetic methods, especially for patients with positive family history. Several candidate genes have been reported but the exact molecular etiology of the disease is yet unknown. In the present study, we performed whole exome sequencing of DDH patients from 28 families with at least two affected first-degree relatives. Four genes previously not associated with DDH (METTL21B, DIS3L2, PPP6R2, and TM4SF19) were identified with the same variants shared among affected family members, in more than two families. Among known association genes, we found damaging variants in DACH1, MYH10, NOTCH2, TBX4, EVC2, OTOG, and SHC3. Mutational burden analysis across the families identified 322 candidate genes, and enriched pathways include the extracellular matrix, cytoskeleton, ion-binding, and detection of mechanical stimulus. Taken altogether, our data suggest a polygenic mode of inheritance for DDH, and we propose that an impaired transduction of the mechanical stimulus is involved in the etiopathological mechanism. Our findings refine our current understanding of candidate causal genes in DDH, and provide a foundation for downstream functional studies.

Comprehensive bioinformatics analysis of susceptibility genes for developmental dysplasia of the hip

Developmental dysplasia of the hip (DDH) is a multifactorial disease, which occurs under environmental and genetic influence. The etiopathogenesis of DDH has not been fully explained. As research progresses, many candidate genes have been found to be closely related to the occurrence of DDH. In this study, we comprehensively examined 16 susceptibility genes of DDH using bioinformatics. COL1A1 encodes the pro-alpha1 chains of type I collagen, which is the major protein component of the bone extracellular matrix (ECM). The genes displaying the most statistically significant co-expression link to COL1A1 are ASPN, TGFB1, DKK1, IL-6, TENM3 and GDF5. DKK1, FRZB and WISP3 are components of the Wnt signaling pathway. CX3CR1 and GDF5 regulate chondrogenesis through the canonical Wnt signaling pathway. ASPN could induce collagen mineralization through binding with collagen and calcium. Integrated bioinformatics analysis indicates that ECM, Wnt signaling pathway and TGF-β signaling pathway are involved in the occurrence of DDH. These provide a basis for further exploring the pathogenesis of DDH.

Pregnancy-Associated Plasma Protein (PAPP)-A2 in Physiology and Disease

The growth hormone (GH)/insulin-like growth factor (IGF) axis plays fundamental roles during development, maturation, and aging. Members of this axis, composed of various ligands, receptors, and binding proteins, are regulated in a tissue- and time-specific manner that requires precise control that is not completely understood. Some of the most recent advances in understanding the implications of this axis in human growth are derived from the identifications of new mutations in the gene encoding the pregnancy-associated plasma protein PAPP-A2 protease that liberates IGFs from their carrier proteins in a selective manner to allow binding to the IGF receptor 1. The identification of three nonrelated families with mutations in the PAPP-A2 gene has shed light on how this protease affects human physiology. This review summarizes our understanding of the implications of PAPP-A2 in growth physiology, obtained from studies in genetically modified animal models and the PAPP-A2 deficient patients known to date.

The Genetic Epidemiology of Joint Shape and the Development of Osteoarthritis

Congruent, low-friction relative movement between the articulating elements of a synovial joint is an essential pre-requisite for sustained, efficient, function. Where disorders of joint formation or maintenance exist, mechanical overloading and osteoarthritis (OA) follow. The heritable component of OA accounts for ~ 50% of susceptible risk. Although almost 100 genetic risk loci for OA have now been identified, and the epidemiological relationship between joint development, joint shape and osteoarthritis is well established, we still have only a limited understanding of the contribution that genetic variation makes to joint shape and how this modulates OA risk. In this article, a brief overview of synovial joint development and its genetic regulation is followed by a review of current knowledge on the genetic epidemiology of established joint shape disorders and common shape variation. A summary of current genetic epidemiology of OA is also given, together with current evidence on the genetic overlap between shape variation and OA. Finally, the established genetic risk loci for both joint shape and osteoarthritis are discussed.

Genetic Study of IL6, GDF5 and PAPPA2 in Association with Developmental Dysplasia of the Hip

Background: Developmental dysplasia of the hip (DDH) is one of the most prevalent skeletal disorders. DDH is considered a pathologic condition with polygenic background, but environmental and mechanic factors significantly contribute to its multifactorial etiology. Inheritance consistent with autosomal dominant type has also been observed. Single-nucleotide polymorphisms (SNPs) in various genes mostly related to formation of connective tissue are studied for a possible association with DDH. Methods: We genotyped three SNPs, rs1800796 located in the promoter region of the IL6 gene, rs143383 located in the 5′ untranslated region (UTR) of the GDF5 gene and rs726252 located in the fifth intron of the PAPPA2 gene. The study consisted of 45 subjects with DDH and 85 controls from all regions of Slovakia. Results: Association between DDH occurrence and studied genotypes affected by aforementioned polymorphisms was confirmed in the case of rs143383 in the GDF5 gene (p = 0.047), where the T allele was over-expressed in the study group. Meanwhile, in the matter of IL6 and PAPPA2, we found no association with DDH (p = 0.363 and p = 0.478, respectively). Conclusions: These results suggest that there is an association between DDH and GDF5 polymorphisms and that the T allele is more frequently presents in patients suffering from DDH.

Replicative verification of susceptibility genes previously identified from families with segregating developmental dysplasia of the hip

BACKGROUND

Developmental dysplasia of the hip (DDH) is a complex hip joint deformity with effects ranging from acetabulum malformation to irreversible hip dislocation. Previous studies suggest a significant association of four variations, teneurin transmembrane protein 3 (TENM3, OMIM * 610083) (chr4:183721398), heparan sulfate proteoglycan 2 (HSPG2, OMIM * 142461) (chr1:22201470), ATPase plasma membrane Ca²⁺ transporting 4 (ATP2B4, OMIM * 108732) (chr1:203682345), and prostaglandin F receptor (PTGFR, OMIM * 600563) (chr1:79002214), with DDH susceptibility in families with segregating DDH. However, the association was not validated in sporadic cases and remains controversial. To confirm the association of the reported variations in these four genes with DDH, we conducted replicative verification in 250 sporadic samples with DDH from a Chinese Han population.

METHODS

We conducted Sanger sequencing after amplifying the variation sites. The results were compared with the reference sequence from the GRCh37 assembly in UCSC ( http://genome.ucsc.edu ).

RESULTS

Replication analysis of 250 sporadic samples by Sanger sequencing indicated that the four variations, TENM3 (OMIM * 610083, chr4:183721398), HSPG2 (OMIM * 142461, chr1:22201470), ATP2B4 (OMIM * 108732, chr1:203682345), and PTGFR (OMIM * 600563, chr1:79002214), were not associated with the susceptibility to DDH in the Chinese Han population.

CONCLUSIONS

Further studies should be performed to identify other variations of these four genes that are potentially associated with DDH by whole-exome sequencing and the results should be verified in different populations.

Current Evidence about Developmental Dysplasia of the Hip in Pregnancy

In adults, developmental dysplasia of the hip (DDH) represents a spectrum of disorders. It is commonly found in women in routine orthopedic practice. Hip dysplasia is a leading precursor of joint laxity; when untreated, it can contribute to chronic modifications, such as thickening of the pulvinar and ligamentum teres (which can also elongate), hypertrophy of the transverse acetabular ligament, and osteoarthritis. DDH is presumed to be associated with alterations in pelvic morphology that may affect vaginal birth by the reduction in the transverse diameter of the pelvic inlet or outlet. Here, we provide an overview of the current knowledge of pregnancy-associated DDH. We primarily focused on how a surgical DDH treatment might influence the pelvic shape and size and the effects on the mechanism of birth. We presented the female pelvis from the standpoint of bone and ligament morphology relative to a pelvic osteotomy. Then, we described whether the pregnancy was impacted by previous surgical DDH treatments, performed from infancy to adulthood. In conclusion, hip dysplasia is not associated with high-risk complications during pregnancy or with increased difficulty in vaginal delivery.

Secreted frizzled-related protein 3 was genetically and functionally associated with developmental dysplasia of the hip

Background: Developmental dysplasia of the hip (DDH) is the most common joint disease in child orthopedics. Secreted Frizzled-Related Protein 3 (FRZB) plays an important role in joint development. however, no direct association between FRZB and DDH has been demonstrated.

Methods: Analysis of genotype distribution and allele frequency for detected single nucleotide polymorphisms (SNP) of FRZB was performed. FRZB expression was assayed in DDH joint tissues. Further experiments to identify the chondrogenic properties of FRZB were conducted. Potential upstream miRNAs for FRZB were assayed in DDH.

Results: Significant difference in genotype distribution for rs3768842 (OR=1.46, P=0.0081) and rs2242040 (OR=0.65, P=0.0067) was found. DDH joint tissues showed significantly higher FRZB expression. FRZB demonstrated chondrogenic and anti-hypertrophic properties in vitro. FRZB modulated cell adhesion pathway and cell spreading by regulating integrins expressions. Upstream miRNAs regulating FRZB expression were identified in DDH synovial fluid. Experiments indicated that downregulated miRNA-454 caused FRZB upregulation in DDH joint.

Conclusion: Dysregulated FRZB and its loci were associated with DDH. As a Wnt antagonist with chondrogenic properties, FRZB modulated cell adhesion pathway and cell spreading by regulating integrins expressions. FRZB in multiple DDH joint tissues might be mediated by the dysregulated miRNA expression profiles in the joint synovial fluid.

25(OH)D status and expression of miR-140 in the serum of patients with developmental dysplasia of the hip

OBJECTIVES

Developmental dysplasia of the hip (DDH) is one of the most common orthopedic birth defects in newborn infants, for whom early detection and treatment are critical. MiR-140 plays an important role in bone development and was found to be regulated by vitamin D receptors in our previous study. This study aimed to investigate vitamin D status and miR-140 expression in the circulation of patients with orthopedic conditions, including DDH.

METHODS

The 25-hydroxyvitamin D (25[OH]D) status and miR-140 expression were determined in the serum of 120 patients with orthopedic conditions. Receiver operating characteristic curves were used to evaluate the potential diagnosis capability of 25(OH)D status and miR-140 expression in DDH. A DDH rat model was also used to verify miR-140 expression in vivo.

RESULTS

We found that most patients with orthopedic conditions have vitamin D insufficiency and deficiency, and patients with DDH are in the insufficiency range. MiR-140 was downregulated in the serum of patients with DDH patients and in the hip joints of rats with DDH. A panel of 25(OH)D and miR-140 showed robust performance in distinguishing DDH from controls.

CONCLUSIONS

Our results indicate that miR-140 may play an important role in DDH, with the potential capability of being a biomarker for the diagnosis of DDH.

Genetics of developmental dysplasia of the hip

In the last decade, the advances in the molecular analyses and sequencing techniques allowed researchers to study developmental dysplasia of the hip (DDH) more thoroughly. Certain chromosomes, genes, loci and polymorphisms are being associated with variable severity of this disorder. The wide range of signs and symptoms is dependent either on isolated or systemic manifestation. Phenotypes of isolated cases range from only a mild ligamental laxity, through subluxation, to a complete dislocation of the femoral head. Systemic manifestation is connected to various forms of skeletal dysplasia and other malformations characterized by significant genetic aberrations. To reveal the background of DDH heredity, multiple studies focused on large sample sizes with an emphasis on the correlation between genotype, phenotype and continuous clinical examination. Etiological risk factors that have been observed and documented in patients include genetic, environmental, and mechanical factors, which significantly contribute to the familial or nonfamilial occurrence and phenotypic variability of this disorder. Still, the multifactorial etiology and pathogenesis of DDH are not yet sufficiently clarified, explained, or understood. Formation of connective tissue, osteogenesis, chondrogenesis, and all other affected pathways and variations in the function of their individual elements contribute to the creation of the pathology in a developing human body. This review article presents an up-to-date list of known DDH associated genes, their products, and functional characteristics.

Genetic variant of COL11A2 gene is functionally associated with developmental dysplasia of the hip in Chinese Han population

OBJECTIVES

Developmental dysplasia of the hip (DDH) is a common skeletal disorder. This study was conducted to demonstrate the association between DDH and a polymorphism rs9277935 of COL11A2 gene.

RESULTS

A significant difference in genotype distribution in a recessive model (TT+GT vs. GG) between two groups (P=0.017) was demonstrated. Analysis in female patients showed significantly greater frequency of minor allele G(0.49 vs. 0.43, p=0.024) and significantly higher distribution of GG genotype (p=0.006). DDH patients were found to have significantly lower COL11A2 expression than controls. Moreover, DDH patients with rs9277935 genotype TT have a significantly increased expression of COL11A2 than those with genotype GG. COL11A2 demonstrated chondrogenic properties in vitro.

CONCLUSION

Polymorphism rs9277935 of gene COL11A2 is a functional variant regulating the expression and the chondrogenic properties of COL11A2 in DDH in Chinese Han population.

METHODS

A case-control candidate gene association study was conducted in 945 patients (350 radiologically confirmed DDH patients and 595 healthy controls). Difference of COL11A2 expression in hip joint tissue was compared between the patients and the controls. Allelic difference in Col11a2 expression by rs9277935 was assessed with luciferase activity. Chondrogenic effects of Col11a2 signaling on BMSCs were also determined in vitro.

Developmental Dysplasia of the Hip: A Review of Etiopathogenesis, Risk Factors, and Genetic Aspects

As one of the most frequent skeletal anomalies, developmental dysplasia of the hip (DDH) is characterized by a considerable range of pathology, from minor laxity of ligaments in the hip joint to complete luxation. Multifactorial etiology, of which the candidate genes have been studied the most, poses a challenge in understanding this disorder. Candidate gene association studies (CGASs) along with genome-wide association studies (GWASs) and genome-wide linkage analyses (GWLAs) have found numerous genes and loci with susceptible DDH association. Studies put major importance on candidate genes associated with the formation of connective tissue (COL1A1), osteogenesis (PAPPA2, GDF5), chondrogenesis (UQCC1, ASPN) and cell growth, proliferation and differentiation (TGFB1). Recent studies show that epigenetic factors, such as DNA methylation affect gene expression and therefore could play an important role in DDH pathogenesis. This paper reviews all existing risk factors affecting DDH incidence, along with candidate genes associated with genetic or epigenetic etiology of DDH in various studies.

Mapping of developmental dysplasia of the hip to two novel regions at 8q23-q24 and 12p12

Developmental dysplasia of the hip (DDH), previously known as congenital hip dislocation, is a frequently disabling condition characterized by premature arthritis later in life. Genetic factors play a key role in the aetiology of DDH. In the present study, a genome-wide linkage scan with the Affymetrix 10K GeneChip was performed on a four-generation Chinese family, which included 19 healthy members and 5 patients. Parametric and non-parametric multipoint linkage analyses were carried out with Genespring GT v.2.0 software, and the logarithm of odds (LOD) score and nonparametric linkage (NPL) score were calculated. Parametric linkage analysis was performed, assuming an autosomal recessive trait with full penetrance and Affymetrix 'Asian' allele frequencies. The strongest evidence for linkage was found on chromosome 8q23-24, with a peak LOD score of 2.658 (θ=0), covering 2.377 Mb from single nucleotide polymorphisms (SNPs) rs724717 to rs720132. This interval included nine additional successive SNPs: rs1566071, rs1902121, rs756404, rs702768, rs777813, rs2033995, rs147959, rs2884367 and rs1898287. The same region also yielded the highest NPL score of 2.883 (P=0.0156) from the non-parametric multipoint linkage analysis. Additionally, the second highest NPL score of 2.727 (P=0.0156) and LOD score of 2.528 (θ=0) were obtained on chromosome 12p12 for three consecutive markers (rs1919980, rs763853 and rs725124). This region overlapped a narrow distance of 0.642 Mb. Notably, in addition to these two regions; no significant linkage was identified for other chromosomal regions (with LOD and NPL scores >2.0). For the first time, at least for this pedigree, the evidence in the present study showed that DDH is mapped to two novel regions at 8q23-q24 and 12p12.

Genetic Predisposition to Developmental Dysplasia of the Hip

BACKGROUND

The etiopathogenesis of developmental dysplasia of the hip (DDH) has not been clarified. This systematic review evaluated current literature concerning all known chromosomes, loci, genes, and their polymorphisms that have been associated or not with the prevalence and severity of DDH.

METHODS

Following the established methodology of Meta-analysis of Observational Studies in Epidemiology guidelines, MEDLINE, EMBASE, and Cochrane Register of Controlled Trials were systematically searched from inception to January 2019.

RESULTS

Forty-five studies were finally included. The majority of genetic studies were candidate gene association studies assessing Chinese populations with moderate methodological quality. Among the most frequently studied are the first, third, 12th,17th, and 20th chromosomes. No gene was firmly associated with DDH phenotype. Studies from different populations often report conflicting results on the same single-nucleotide polymorphism (SNP). The SNP rs143384 of GDF5 gene on chromosome 20 demonstrated the most robust relationship with DDH phenotype in association studies. The highest odds of coinheritance in linkage studies have been reported for regions of chromosome 3 and 13. Five SNPs have been associated with the severity of DDH. Animal model studies validating previous human findings provided suggestive evidence of an inducing role of mutations of the GDF5, CX3CR1, and TENM3 genes in DDH etiopathogenesis.

CONCLUSION

DDH is a complex disorder with environmental and genetic causes. However, no firm correlation between genotype and DDH phenotype currently exists. Systematic genome evaluation in studies with larger sample size, better methodological quality, and assessment of DDH patients is necessary to clarify the DDH heredity. The role of next-generation sequencing techniques is promising.

Developmental dysplasia of the hip: a systematic literature review of the genes related with its occurrence

Developmental dysplasia of the hip (DDH) is one of the most prevalent congenital malformations. It has a wide spectrum of anatomical abnormalities of the hip joint and is characterized by mild or incomplete formation of the acetabulum leading to laxity of the joint capsule, secondary deformity of the proximal femur and irreducible hip dislocation. It is the leading cause of early hip osteoarthritis in young individuals.

Both genetic and environmental factors have been proposed to play an important role in the pathogenesis of DDH. A high prevalence is present in Asian, Caucasian, Mediterranean and American populations, with females being more frequently affected. We evaluated a variety of genetic studies indexed in the PubMed database.

Several susceptive genes, including WISP3, PAPPA2, HOXB9, HOXD9, GDF5, TGF Beta 1, CX3CR1, UQCC, COL1A1, TbX4 and ASPN have been identified as being associated with the development of DDH. Moreover, genetic association has also been reported between hip dysplasia and other comorbidities. Even though genetic components are a crucial part in the aetiology of DDH, several DDH susceptibility genes need further investigation.

The purpose of this review is to present current literature evidence regarding genes responsible for DDH development.

Cite this article: EFORT Open Rev 2019;4:595-601. DOI: 10.1302/2058-5241.4.190006

Abnormal expression of Pappa2 gene may indirectly affect mouse hip development through the IGF signaling pathway

INTRODUCTION

Developmental dysplasia of the hip (DDH) is a major cause of disability in children, and the genetic mechanism of this disease remains unclear. In our previous study, we found that pregnancy-associated plasma protein-A2 (PAPP-A2) was associated with DDH significantly.

OBJECTIVES

The aim of this study was to investigate the insulin-like growth factor (IGF) expression and collagen synthesis as well as cartilage proliferation-related proteins in the case of abnormal expression of Pappa2 in mice to research the relationship between PAPP-A2 and the pathological changes of DDH.

METHODS

In vivo animal experiments, the mice were directly injected with 50 µl of Cas9/PAPP-A2 sgRNA lentiviruses around the hip to downregulate the Pappa2 gene expression and injected with control lentiviruses on the other side, then to observe the expression and localization of related proteins. And in an in vitro experiment, mice fibroblasts and primary chondrocytes were cultured with insulin-like growth factor binding protein-5 (IGFBP-5) protein, PAPP-A2 protein and Cas9/PAPP-A2 sgRNA lentiviruses to detect of related proteins and mRNA expression.

RESULTS

Cartilage proliferation-related proteins demonstrated a significant decrease in the PAPP-A2 knockdown hips acetabulum and femoral head cartilage, meanwhile the IGF expression was also downregulated in the soft tissue around the acetabulum compared with the control hips. Furthermore, the role PAPP-A2 played in chondrocytes and fibroblasts was the same as in the in vivo experiments, downregulation of PAPP-A2 expression or upregulation of IGFBP-5 expression can reduce collagen synthesis and cartilage proliferation.

CONCLUSIONS

PAPP-A2 may be involved in the development of the mouse hip joint by interfering the fibrous and cartilaginous metabolism via IGF pathway-associated proteins pathway.

Ten- and 20-year Survivorship of the Hip After Periacetabular Osteotomy for Acetabular Dysplasia

INTRODUCTION

Acetabular dysplasia is a multifactorial condition characterized by a shallow hip socket with predisposition to osteoarthritis of the hip. The Bernese periacetabular osteotomy (PAO), developed by Reinhold Ganz in 1984, reorients the dysplastic hip joint to provide more uniform coverage of the femoral head and to extend the longevity of the native hip. Since 1987, the senior author performed the Bernese PAO on more than 430 patients. We performed a cross-sectional retrospective study on this cohort of patients to determine the 10- and 20-year survivorship after PAO in addition to assessing functional outcomes and radiographic parameters.

METHODS

Four hundred thirty-four patients were treated for acetabular dysplasia with PAO by the senior surgeon from 1987 to 2014. Data were obtained for 302 hips in 258 patients in a retrospective fashion from medical records and/or mail-in/phone questionnaires. Functional outcome data consisted of postoperative Hip Osteoarthritis Outcome Score and University of California-Los Angeles Activity Score. Pre- and postoperative radiographs were used to determine lateral center-edge angle, anterior center-edge angle, Tönnis angle/grade, and head-to-ilioischial line distance. Survivorship of the native hip was determined by Kaplan-Meier analysis.

RESULTS

Of the 302 hips analyzed, 248 were still surviving native hips and 54 had gone on to a total hip arthroplasty (THA) at the time of data acquisition. The average age of patients in the entire cohort at PAO was 32.7 years (range, 13 to 63 years). Of the 258 patients, 215 were female patients (83.3%) and 43 male patients (16.8%). The average age of patients in the surviving group at PAO was 32.3 years, and the average age of patients in the THA group was 36.6 years (P < 0.01). At the time of data acquisition, follow-up ranged from 2 to 27 years (average, 11.2 years). Hip Osteoarthritis Outcome Score and University of California-Los Angeles Activity Score are reported for the surviving native hips after PAO. Radiographic analyses for surviving and failed hips are described, with pre- and postoperative Tönnis grade being statistically significant predictors for conversion to THA (P < 0.01). Survivorship of the native hip was 86% at 10 years and 60% at 20 years in the surviving cohort. Survivorship stratified by age at the time of PAO demonstrated a 10-year survivorship of 93.3%, 90.1%, 81.6%, and 63.2% at ages 20, 30, 40, and 50 years, respectively. No notable difference exists in survivorship between male and female patients; however, male patients had a trend toward lower survivorship compared with female patients at 15 years.

CONCLUSION

The 10- and 20-year survivorship of the native hip after PAO is approximately 86% and 60%, respectively, in our cohort of 302 hips. Older age at the time of PAO and higher Tönnis grade are negative prognostic factors for joint survival after PAO. Surviving hips after PAO have good functional outcomes even up to 20 years after surgery. This survivorship analysis represents one of the largest and longest survival studies of patients after PAO, and our results are consistent with other published studies.

LEVEL OF EVIDENCE

Level III.

Genetic variant of WIF1 gene is functionally associated with developmental dysplasia of the hip in Han Chinese population

Developmental dysplasia of the hip (DDH) is a common skeletal disorder. Studies have demonstrated a significant role of WIF1 gene in skeletal development. The present study was conducted to reveal the association between DDH and gene WIF1. A two-stage case-control candidate gene association study was conducted in total 1573 samples (586 DDH patients and 987 healthy controls) in this study. Polymorphism rs3782499 was genotyped in all samples. Difference of WIF1 expression in hip joint tissue was compared between the patients and the controls. WIF1 expression was compared among different genotypes in DDH patients. The SNP rs3782499 was found significantly associated with DDH in the two-stage study with 585 patients and 987 controls. There was a significant difference in allele frequency (p = 4.37 * 10^-5) and genotype distribution in a recessive model (AG + GG vs. AA). DDH patients were found to have significantly higher WIF1 expression than controls. Moreover, Patients with rs3782499 genotype AA have a significantly increased expression of WIF1 than those with GG. To conclude, polymorphism rs3782499 of WIF1 gene is a functional variant regulating the expression of WIF1 in DDH in Chinese Han population, which might be a potential biomarker for the early diagnosis of DDH.

Expression of PAPP-A2 and IGF Pathway-Related Proteins in the Hip Joint of Normal Rat and Those with Developmental Dysplasia of the Hip

Developmental dysplasia of the hip (DDH) is one of the major causes of child disability and early osteoarthritis. Genetic factors play an important role, but which still remain unclear. Pregnancy-associated plasma protein-A2 (PAPP-A2), a special hydrolase of insulin-like growth factor binding protein-5 (IGFBP-5), has been confirmed to be associated with DDH by previous studies. The aim of this study was firstly, to investigate the expression of PAPP-A2 and insulin-like growth factor (IGF) pathway-related proteins in normal rat's hip joints; secondly, to compare the variations of those proteins between DDH model rats and normal ones. The DDH model was established by swaddling the rat's hind legs in hip adduction and extension position. The hip joints were collected for expression study of fetal rats, normal newborn rats, and DDH model rats. Positive expression of PAPP-A2 and IGF pathway-related proteins was observed in all the hip joints of growing-stage rats. Ultimately, IGF1 was downregulated; insulin-like growth factor 1 receptor (IGF1R) showed an opposite trend in DDH rats when compared with normal group. The PAPP-A2 and IGF pathway-associated proteins may also be involved in the development of the rat's hip joint, which bring the foundation for further revealing the pathogenic mechanism of DDH.

Association analysis on polymorphisms in WISP3 gene and developmental dysplasia of the hip in Han Chinese population: A case-control study

Developmental dysplasia of the hip (DDH) is a common skeletal disorder whereby genetic factors play a role in etiology. Multiple genes have been reported to be associated with the occurrence of DDH. WISP3 gene was found to be a causative gene for progressive pseudorheumatoid dysplasia (PPD). Reports of WISP3 gene in association with DDH are lacking. We conducted a case-control candidate gene association study enrolling three hundred and eighty-six patients with radiology confirmed DDH and 558 healthy controls. Additional haplotype-analysis was conducted to find the significant haplotype for DDH. Five SNPs rs69306665 (upstream of WISP3), rs1022313 (WISP3), rs1230345 (WISP3), rs17073268 (WISP3) and rs10456877 (downstream of WISP3) were identified for association with DDH, showing significant difference of allele frequencies with similar odds ratio ranging from 0.71 to 0.77 (p < 0.01) between cases and controls. Two haplotypes were identified between cases and controls through haplotype analysis: AAAAA with an odds ratio of 0.76 (95% CI: 0.60-0.98, p = 0.032299) and GGCGG with an odds ratio of 1.67 (95% CI: 1.37-2.04, p = 3.67 ∗ 10^-7). The results suggested WISP3 gene was associated with DDH in Chinese Han population. GGCGG haplotype might be a biomarker for DDH.

Genome-Wide Study of Subcutaneous and Visceral Adipose Tissue Reveals Novel Sex-Specific Adiposity Loci in Mexican Americans

OBJECTIVE

This study aimed to explore the genetic mechanisms of regional fat deposition, which is a strong risk factor for metabolic diseases beyond total adiposity.

METHODS

A genome-wide association study of 7,757,139 single-nucleotide polymorphisms (SNPs) in 983 Mexican Americans (n_male  = 403; n_female  = 580) from the Insulin Resistance Atherosclerosis Family Study was performed. Association analyses were performed with and without sex stratification for subcutaneous adipose tissue, visceral adipose tissue (VAT), and visceral-subcutaneous ratio (VSR) obtained from computed tomography.

RESULTS

The strongest signal identified was SNP rs2185405 (minor allele frequencies [MAF] = 40%; P_VAT = 1.98 × 10^-8 ) with VAT. It is an intronic variant of the GLIS family zinc finger 3 gene (GLIS3). In addition, SNP rs12657394 (MAF = 19%) was associated with VAT in males (P_male = 2.39×10^-8 ; P_female = 2.5 × 10^-3 ). It is located intronically in the serum response factor binding protein 1 gene (SRFBP1). On average, male carriers of the variant had 24.6 cm² increased VAT compared with noncarriers. Subsequently, genome-wide SNP-sex interaction analysis was performed. SNP rs10913233 (MAF = 14%; P_int = 3.07 × 10^-8 ) in PAPPA2 and rs10923724 (MAF = 38%; P_int = 2.89 × 10^-8 ) upstream of TBX15 were strongly associated with the interaction effect for VSR.

CONCLUSIONS

Six loci were identified with genome-wide significant associations with fat deposition and interactive effects. These results provided genetic evidence for a differential basis of fat deposition between genders.

Genetic association study of common variants in TGFB1 and IL-6 with developmental dysplasia of the hip in Han Chinese population

Developmental dysplasia of the hip (DDH) is a congenital or developmental deformation or misalignment of the hip joint that is affected by environmental and genetic factors. Recently, polymorphisms in both TGFB1 and IL-6 have been identified as being significantly associated with hip osteoarthritis in Caucasians. In this study, we conducted a case-control study involving 4,206 Han Chinese individuals to investigate the effects of TGFB1 and IL-6 on the disease status and severity of DDH. A total of 32 single-nucleotide polymorphisms (SNPs) were selected to ensure coverage of the two genetic loci. We found SNP rs1800470 in TGFB1 (OR = 1.255, P = 0.0004) and rs1800796 (OR = 0.84, P = 0.0228) in IL-6 to be significantly associated with DDH in this cohort. Further haplotype-based analysis replicated this significant result. Another SNP in IL-6, rs1800796, showed a marginally significant association with DDH. As a non-synonymous SNP, rs1800470 alters the amino acid sequence of the polypeptide encoded by TGFB1; however, bioinformatics analyses revealed that this SNP has limited functional significance. No significant results were obtained in an association study focusing on the severity of DDH and epistasis analysis. Our findings support an important role for TGFB1 in the risk of DDH. Further research is needed to validate the weak association between rs1800796 in IL-6 and DDH.

A common variant of ubiquinol-cytochrome c reductase complex is associated with DDH

Purpose

Genetic basis of Developmental dysplasia of the hip (DDH) remains largely unknown. To find new susceptibility genes for DDH, we carried out a genome-wide association study (GWAS) for DDH.

Methods

We enrolled 386 radiology confirmed DDH patients and 558 healthy controls (Set A) to conduct a genome-wide association study (GWAS). Quality-control was conducted at both the sample and single nucleotide polymorphism (SNP) levels. We then conducted a subsequent case-control study to replicate the association between a promising loci, rs6060373 in UQCC gene and DDH in an independent set of 755 cases and 944 controls (set B).

Results

In the DDH GWAS discovering stage, 51 SNPs showed significance of less than 10^-4, and another 577 SNPs showed significance of less than 10-3. In UQCC, all the 12 genotyped SNPs showed as promising risk loci. Genotyping of rs6060373 in set A showed the minor allele A as a promising risk allele (p = 4.82*10^-7). In set A, the odds ratio of allele A was 1.77. Genotyping of rs6060373 in Set B produced another significant result (p = 0.0338) with an odds ratio of 1.18 for risk allele A. Combining set A and set B, we identified a total p value of 3.63*10^-6 with the odds ratio of 1.35 (1.19–1.53) for allele A.

Conclusion

Our study demonstrates common variants of UQCC, specifically rs6060373, are associated with DDH in Han Chinese population.

Two single-nucleotide polymorphisms in the DKK1 gene are associated with developmental dysplasia of the hip in the Chinese Han female population

AIMS

Developmental dysplasia of the hip (DDH) is a common congenital or acquired skeletal disease characterized by subluxation, dislocation, or dysplasia of the hip joint. This study aimed to explore the potential impact of Dickkopf-1 (DKK1) gene polymorphisms on embryonic hip joint development and the course of DDH.

METHODS

One hundred ninety-two unrelated Chinese Han female DDH patients and 191 unrelated, healthy, ethnically matched female controls were recruited and genotyped for two tag single-nucleotide polymorphisms (SNPs) of DKK1 using the Sequenom method.

RESULTS

One of the two DKK1 tag SNPs, rs11001560, was not shown to be significantly statistically different in allele frequency between DDH patients and control groups (χ(2)=0.898, df=1, p=0.343). However, a significant difference in genotype distribution was observed (χ(2)=21.987, df=2, p<0.0001). For SNP rs1569198, significant differences were observed in both allele frequency and genotype distribution between the DDH group and control group (χ(2)=31.484, df=1, p<0.0001 and χ(2)=30.323, df=2, p<0.0001). The A allele frequency of rs1569198 has a significant association to increased risk of DDH development (odds ratio [OR]=3.032, 95% confidence interval [95% CI]: 2.034-4.519).

CONCLUSION

In conclusion, the association between two tag SNPs of the DKK1 gene and DDH development reached statistical significance in our study population; the results of our genetic association analysis indicated that DKK1 may be a good candidate responsible for DDH development in the Chinese Han female population.

A replication study for the association of rs726252 in PAPPA2 with developmental dysplasia of the hip in Chinese Han population

Developmental dysplasia of the hip (DDH) is a common developmental hip disorder, which ranges from mild acetabulum malformation to irreducible hip dislocation. A previous study suggested a significant association of pregnancy-associated plasma protein-A2 (PAPPA2) with DDH susceptibility in Chinese Han population. But with the consideration of the sample size, the association was still debatable. To confirm the association of the reported single nucleotide polymorphism (SNP) in PAPPA2, rs726252 with DDH, we conducted a case-control study in a larger number of subjects. We genotyped rs726252 in 697 DDH subjects and 707 control subjects by TaqMan assay. The association between this SNP and DDH was evaluated statistically. No significant difference was found in any comparison of genotype distribution nor allele frequency between cases and controls. Our replication study indicated that the association between rs726252 and DDH in Chinese Han population was debatable. The association between PAPPA2 and DDH should be evaluated by additional studies.

Association of a single nucleotide polymorphism in HOXB9 with developmental dysplasia of the hip: a case-control study

Developmental dysplasia of the hip (DDH) is one of the most common skeletal disorders. It comprises a spectrum of abnormalities, including shallow acetabulum and decreased coverage of the femoral head. Genetic component plays a considerable role in the aetiology of DDH. HOXB9 may be involved in the aetiology and pathogenesis of DDH, as it plays an important role in the development of the limbs. Our objective was to evaluate whether single nucleotide polymorphisms (SNPs) of HOXB9 (rs2303486 and rs8844) were associated with DDH in Chinese population. The HOXB9 tag SNPs were genotyped in 460 DDH cases and 562 control subjects by Taqman assay, and their association was examined. rs8844 was not associated with DDH. rs2303486 was associated with DDH in the dominant genetic model (p = 0.037; odds ratio (OR) = 1.32; 95% confidence interval (CI) = 1.02–1.71). After stratification by sex, significant association of the dominant genetic model still existed in the female subjects (p = 0.015; OR = 1.46; 95% CI = 1.08–1.98),but not in the male subjects. After stratification by severity, we discovered an association with hip dislocation in the dominant model(p=0.042; OR = 1.35; 95% CI = 1.01–1.80), but not with subluxation or instability. HOXB9 is associated with DDH in Chinese.

Genome wide analysis indicates genes for basement membrane and cartilage matrix proteins as candidates for hip dysplasia in Labrador Retrievers

Hip dysplasia, an abnormal laxity of the hip joint, is seen in humans as well as dogs and is one of the most common skeletal disorders in dogs. Canine hip dysplasia is considered multifactorial and polygenic, and a variety of chromosomal regions have been associated with the disorder. We performed a genome-wide association study in Dutch Labrador Retrievers, comparing data of nearly 18,000 single nucleotide polymorphisms (SNPs) in 48 cases and 30 controls using two different statistical methods. An individual SNP analysis based on comparison of allele frequencies with a χ(2) statistic was used, as well as a simultaneous SNP analysis based on Bayesian variable selection. Significant association with canine hip dysplasia was observed on chromosome 8, as well as suggestive association on chromosomes 1, 5, 15, 20, 25 and 32. Next-generation DNA sequencing of the exons of genes of seven regions identified multiple associated alleles on chromosome 1, 5, 8, 20, 25 and 32 (p<0.001). Candidate genes located in the associated regions on chromosomes 1, 8 and 25 included LAMA2, LRR1 and COL6A3, respectively. The associated region on CFA20 contained candidate genes GDF15, COMP and CILP2. In conclusion, our study identified candidate genes that might affect susceptibility to canine hip dysplasia. These genes are involved in hypertrophic differentiation of chondrocytes and extracellular matrix integrity of basement membrane and cartilage. The functions of the genes are in agreement with the notion that disruptions in endochondral bone formation in combination with soft tissue defects are involved in the etiology of hip dysplasia.

Pregnancy associated plasma protein A2 (PAPP-A2) affects bone size and shape and contributes to natural variation in postnatal growth in mice

Pregnancy associated plasma protein A2 (PAPP-A2) is a protease of insulin-like growth factor binding protein 5 and is receiving increasing attention for its roles in pregnancy and postnatal growth. The goals of the present study were to characterize the effects of PAPP-A2 deletion on bone size and shape in mice at 10 weeks of age, and to determine whether Pappa2 is the gene responsible for a previously-identified quantitative trait locus (QTL) contributing to natural variation in postnatal growth in mice. Mice homozygous for constitutive PAPP-A2 deletion were lighter than wild-type littermates, and had smaller mandible dimensions and shorter skull, humerus, femur, tibia, pelvic girdle, and tail bone. Furthermore, PAPP-A2 deletion reduced mandible dimensions and the lengths of the skull, femur, pelvic girdle, and tail bone more than would be expected due to the effect on body mass. In addition to its effects on bone size, PAPP-A2 deficiency also altered the shape of the mandible and pelvic girdle, as assessed by geometric morphometrics. Mice homozygous for the PAPP-A2 deletion had less deep mandibles, and pelvic girdles with a more feminine shape. Using a quantitative complementation test, we confirmed that Pappa2 is responsible for the effects of the previously-identified QTL, demonstrating that natural variation in the Pappa2 gene contributes to variation in postnatal growth in mice. If similar functional variation in the Pappa2 gene exists in other species, effects of this variation on the shape of the pelvic girdle might explain the previously-reported associations between Pappa2 SNPs and developmental dysplasia of the hip in humans, and birthing in cattle.

Genetic study on developmental dysplasia of the hip

BACKGROUND

Developmental dysplasia of the hip (DDH) is a developmental disorder of the hip joint that results in an abnormal socket of the femoral head, ranging from instability, subluxation and complete dislocation of the hip joint. DDH has a considerable genetic component.

DESIGN

We reviewed the recent progress on genetic study of DDH.

RESULTS

By linkage and case-control association studies, DDH loci have been identified with several susceptibility genes that involve in bone and joint biology; however, no unequivocal genes with global significance have been detected. The current problem of the association study in DDH is discussed.

CONCLUSIONS

By advanced technologies and international collaboration, we need to find more susceptibility genes and bridge the gap between genetic evidence and molecular mechanisms.