Association of estrogen receptor gene polymorphisms with susceptibility to adolescent idiopathic scoliosis

Genetics and pathogenesis of scoliosis

Background

Scoliosis is defined as a lateral spine curvature of at least 10° with vertebral rotation, as seen on a posterior-anterior radiograph, often accompanied by reduced thoracic kyphosis. Scoliosis affects all age groups: idiopathic scoliosis is the most common spinal disorder in children and adolescents, while adult degenerative scoliosis typically affects individuals over fifty. In the United States, approximately 3 million new cases of scoliosis are diagnosed annually, with a predicted increase in part due to global aging. Despite its prevalence, the etiopathogenesis of scoliosis remains unclear.

Methods

This comprehensive review analyzes the literature on the etiopathogenetic evidence for both idiopathic and adult degenerative scoliosis. PubMed and Google Scholar databases were searched for studies on the genetic factors and etiopathogenetic mechanisms of scoliosis development and progression, with the search limited to articles in English.

Results

For idiopathic scoliosis, genetic factors are categorized into three groups: genes associated with susceptibility, disease progression, and both. We identify gene groups related to different biological processes and explore multifaceted pathogenesis of idiopathic scoliosis, including evolutionary adaptations to bipedalism and developmental and homeostatic spinal aberrations. For adult degenerative scoliosis, we segregate genetic and pathogenic evidence into categories of angiogenesis and inflammation, extracellular matrix degradation, neural associations, and hormonal influences. Finally, we compare findings in idiopathic scoliosis and adult degenerative scoliosis, discuss current limitations in scoliosis research, propose a new model for scoliosis etiopathogenesis, and highlight promising areas for future studies.

Conclusions

Scoliosis is a complex, multifaceted disease with largely enigmatic origins and mechanisms of progression, keeping it under continuous scientific scrutiny.

Single nucleotide polymorphisms of estrogen receptors are risk factors for the progression of adolescent idiopathic scoliosis: a systematic review and meta-analyses

BACKGROUND

There have been some studies on the occurrence of ESR1 and 2 polymorphisms and AIS, but some data extraction is wrong, and there are no studies on the progress of AIS.

METHODS

Computer searches were conducted on PubMed, EMBASE, ScienceDirect and Scopus from the establishment of the database to April 2024. Cross-sectional and case-control studies on estrogen receptor ESR1, two single nucleotide polymorphisms, and the occurrence and development of AIS were collected, and statistical analysis was performed using the Revman 5.3 software.

RESULTS

In the comparison of the association between single nucleotide polymorphisms of estrogen receptors ESR1 and 2 and the occurrence and development of AIS, eight studies were included, including 2706 cases and 1736 controls.The results showed that the AA genotype [OR = 0.50,95%Cl(0.34,0.72),P = 0.0003] at the XbaI locus of ESR1,CC genotype [OR = 1.67,95%Cl(1.16,2.42), P = 0.006], C allele [OR = 1.28,95%Cl(1.03,1.59),P = 0.03], and T allele [OR = 0.78,95%] Cl(0.63,0.97),P = 0.03] at the PvuII locus of ESR1 and TT genotype [OR = 0.50,95%Cl(0.26,0.93),P = 0.03] at the AlwNI locus of ESR2 showed statistically significant differences between the progressive and stable AIS patients.

CONCLUSION

Single nucleotide polymorphisms of ESR1 and ESR2 were not related to the occurrence of AIS; however, some of them were related to the progression of AIS.

Comparative analysis of paraspinal muscle imbalance between idiopathic scoliosis and congenital scoliosis from the transcriptome aspect

Background

Previous studies have analyzed paraspinal muscle imbalance in idiopathic scoliosis (IS) with methods including imaging, histology and electromyography. However, whether paraspinal muscle imbalance is the cause or the consequence of spinal deformities in IS remains unclear. Comparison of paraspinal muscle imbalance between IS and congenital scoliosis (CS) may shed some light on the causality of paraspinal muscle imbalance and IS. This study aimed to elucidate the generality and individuality of paraspinal muscle imbalance between IS and CS from gene expression.

Methods

Five pairs of surgical-treated IS and CS patients were matched. Bilateral paraspinal muscles at the apex were collected for transcriptome sequencing. Differentially expressed genes (DEGs) between the convexity and concavity in both IS and CS were identified. Comparison of DEGs between IS and CS was conducted to discriminate IS-specific DEGs from DEGs shared by both IS and CS. Bioinformatics analysis was performed. The top 10 hub genes in the protein-protein interaction (PPI) network of IS-specific DEGs were validated by quantitative PCR (qPCR) in 10 pairs of IS and CS patients.

Results

A total of 370 DEGs were identified in IS, whereas 380 DEGs were identified in CS. Comparison of DEGs between IS and CS identified 59 DEGs shared by IS and CS, along with 311 DEGs specific for IS. These IS-specific DEGs were enriched in response to external stimulus and signaling receptor binding in GO terms and calcium signaling pathway in KEGG pathways. The top 10 hub genes in the PPI network of IS-specific DEGs include BDKRB1, PRH1-TAS2R14, CNR2, NPY4R, HTR1E, CXCL3, ICAM1, ALB, ADIPOQ, and GCGR. Among these hub genes, the asymmetrical expression of PRH1-TAS2R14 and ADIPOQ in IS but not CS were validated by qPCR.

Conclusions

Transcriptomic differences in bilateral paraspinal muscles between the convexity and concavity in IS share few similarities with those in CS.

Structure, ligands, and roles of GPR126/ADGRG6 in the development and diseases

Adhesion G protein-coupled receptors (aGPCRs) are the second largest diverse group within the GPCR superfamily, which play critical roles in many physiological and pathological processes through cell-cell and cell-extracellular matrix interactions. The adhesion GPCR Adgrg6, also known as GPR126, is one of the better-characterized aGPCRs. GPR126 was previously found to have critical developmental roles in Schwann cell maturation and its mediated myelination in the peripheral nervous system in both zebrafish and mammals. Current studies have extended our understanding of GPR126-mediated roles during development and in human diseases. In this review, we highlighted these recent advances in GPR126 in expression profile, molecular structure, ligand-receptor interactions, and associated physiological and pathological functions in development and diseases.

Knowledge mapping of idiopathic scoliosis genes and research hotspots (2002-2022): a bibliometric analysis

Background

The etiology of idiopathic scoliosis (IS) remains unclear. Gene-based studies on genetic etiology and molecular mechanisms have improved our understanding of IS and guided treatment and diagnosis. Therefore, it is imperative to explicate and demarcate the preponderant areas of inquiry, key scholars, and their aggregate scholarly output, in addition to the collaborative associations amongst publications or researchers.

Methods

Documents were retrieved from the Web of Science Core Collection (WoSCC) with the following criteria: TS = ("idiopathic scoliosis" AND gene) refined by search operators (genomic OR "hereditary substance" OR "germ plasm" OR Cistrons OR genetics OR genetic OR genes OR Polygenic OR genotype OR genome OR allele OR polygenes OR Polygene) AND DOCUMENT TYPES (ARTICLE OR REVIEW), and the timespan of 2002-01-01 to 2022-11-26. The online bibliometric analysis platform (bibliometric), bibliographic item co-occurrence matrix builder (BICOMB), CiteSpace 6.1. R6 and VOS viewer were used to evaluate articles for publications, nations, institutions, journals, references, knowledge bases, keywords, and research hotspots.

Results

A total of 479 documents were retrieved from WoSCC. Fourty-four countries published relevant articles. The country with the most significant number of articles was China, and the institution with the most significant number of articles was Nanjing University. Citation analysis formed eight meaningful clusters and 16 high-frequency keywords. (2) The citation knowledge map included single nucleotide polymorphisms, whole exome sequencing, axonal dynamin, drug development, mesenchymal stem cells, dietary intake, curve progression, zebrafish development model, extracellular matrix, and rare variants were the current research hotspots and frontiers.

Conclusions

Recent research has focused on IS-related genes, whereas the extracellular matrix and unusual variants are research frontiers and hotspots. Functional analysis of susceptibility genes will prove to be valuable for identifying this disease.

Differential Regulation of POC5 by ERα in Human Normal and Scoliotic Cells

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional spinal deformity. The incidence of AIS in females is 8.4 times higher than in males. Several hypotheses on the role of estrogen have been postulated for the progression of AIS. Recently, Centriolar protein gene POC5 (POC5) was identified as a causative gene of AIS. POC5 is a centriolar protein that is important for cell cycle progression and centriole elongation. However, the hormonal regulation of POC5 remains to be determined. Here, we identify POC5 as an estrogen-responsive gene under the regulation of estrogen receptor ERα in normal osteoblasts (NOBs) and other ERα-positive cells. Using promoter activity, gene, and protein expression assays, we found that the POC5 gene was upregulated by the treatment of osteoblasts with estradiol (E2) through direct genomic signaling. We observed different effects of E2 in NOBs and mutant POC5^A429V AIS osteoblasts. Using promoter assays, we identified an estrogen response element (ERE) in the proximal promoter of POC5, which conferred estrogen responsiveness through ERα. The recruitment of ERα to the ERE of the POC5 promoter was also potentiated by estrogen. Collectively, these findings suggest that estrogen is an etiological factor in scoliosis through the deregulation of POC5.

The asymmetrical ESR1 signaling in muscle progenitor cells determines the progression of adolescent idiopathic scoliosis

Adolescent Idiopathic Scoliosis (AIS) is a common pediatric skeletal disease highly occurred in females. The pathogenesis of AIS has not been fully elucidated. Here, we reveal that ESR1 (Estrogen Receptor 1) expression declines in muscle stem/progenitor cells at the concave side of AIS patients. Furthermore, ESR1 is required for muscle stem/progenitor cell differentiation and disrupted ESR1 signaling leads to differentiation defects. The imbalance of ESR1 signaling in the para-spinal muscles induces scoliosis in mice, while reactivation of ESR1 signaling at the concave side by an FDA approved drug Raloxifene alleviates the curve progression. This work reveals that the asymmetric inactivation of ESR1 signaling is one of the causes of AIS. Reactivation of ESR1 signaling in para-spinal muscle by Raloxifene at the concave side could be a new strategy to treat AIS.

Upregulated estrogen receptors impairs myogenesis and elevates adipogenesis related factor levels in the paravertebral muscles of patients with idiopathic scoliosis

The prevalence of idiopathic scoliosis (IS) is 2-3% worldwide and is more common in girls. Estrogen receptors (ERs) is supposed to be related to sex differences and development of IS. Meanwhile, paravertebral muscle (PVM) abnormalities play important roles in the pathogenesis of IS. But the changes of ERs between the PVMs from IS patients and controls, and the mechanism by which ERs may affect IS patients remain unclear. Thus, the expression levels of ERs, myogenesis regulator (MYOG) and adipogenesis related factors (CEBPA, PPARγ, FABP4), as well as morphological changes in the PVMs and primary skeletal muscle mesenchymal progenitor cells (hSM-MPCs) of IS patients and controls were investigated. Increased expression levels of ERs and CEBPA, PPARγ, FABP4, together with severe myofiber necrosis and fat infiltration, were found in the PVMs of IS patients. Meanwhile, upregulated ERs, FABP4 and CEBPA, downregulated MYOG and impaired myogenesis were also revealed in the hSM-MPCs of IS patients compared with those of controls. Upregulation of ERs inhibited myogenesis but increased expression of CEBPA and FABP4 in C2C12 myoblasts. Nevertheless, treatment of ER antagonist increased expression of MYOG, enhanced myogenesis and decreased expression of CEBPA and FABP4 in skeletal muscle cells of IS patients. Therefore, our study suggested that PVMs specific upregulation of ERs could impair myogenesis and increase the expression of adipogenesis related factors, further leading to PVMs abnormalities in IS patients.

Exploring the association between specific genes and the onset of idiopathic scoliosis: a systematic review

Background

Idiopathic Scoliosis (IS) is the most common spinal deformity in adolescents, accounting for 80% of all spinal deformities. However, the etiology remains uncertain in most cases, being identified as Adolescent Idiopathic Scoliosis (AIS). IS treatments range from observation and sport to bracing or surgery. Several risk factors including sex and familiarity, have been linked with IS. Although there are still many uncertainties regarding the cause of this pathology, several studies report a greater incidence of the defect in families in which at least one other first degree relative is affected. This study systematically reviews the available literature to identify the most significant genes or variants related to the development and onset of IS.

Methods

The research question was formulated using a PIOS approach on the following databases: Medline, Embase, Cinahl, Scopus, Web of Science and Google Scholar. The search was performed from July to August 2021, and articles from the inception of the database to August 2021 were searched.

Results

24 of the 919 initially identified studies were included in the present review. The 24 included studies observed a total of 16,316 cases and 81,567 controls. All the considered studies stated either the affected gene and/or specific SNPs. CHD7, SH2B1, ESR, CALM1, LBX1, MATN1, CHL1, FBN1 and FBN2 genes were associated with IS development.

Conclusions

Although association can be found in some candidate genes the field of research regarding genetic association with the onset of IS still requires more information.

Predictive value of single-nucleotide polymorphisms in curve progression of adolescent idiopathic scoliosis

PURPOSE

Genetic diagnosis is a promising approach because several single-nucleotide polymorphisms (SNPs) associated with adolescent idiopathic scoliosis (AIS) progression have been reported. We review the predictive value of SNPs in curve progression of adolescent idiopathic scoliosis.

METHODS

We reviewed DNA-based prognostic testing to predict curve progression. Then, the multiple polymorphisms in loci related to AIS progression were also reviewed, and we elucidated the predictive value of SNPs from four functional perspectives, including endocrine metabolism, neuromuscular system, cartilage and extracellular matrix, enzymes, and cytokines.

RESULTS

The ScoliScores were less successful predictors than expected, and the weak power of predictive SNPs might account for its failure. Susceptibility loci in ESR1, ESR2, GPER, and IGF1, which related to endocrine metabolism, have been reported to predict AIS progression. Neuromuscular imbalance might be a potential mechanism of scoliosis, and SNPs in LBX1, NTF3, and SOCS3 have been reported to predict the curve progression of AIS. Susceptibility loci in SOX9, MATN1, AJAP1, MMP9, and TIMP2, which are related to cartilage and extracellular matrix, are also potentially related to AIS progression. Enzymes and cytokines play essential roles in regulating bone metabolism and embryonic development. SNPs in BNC2, SLC39A8, TGFB1, IL-6, IL-17RC, and CHD7 were suggested as predictive loci for AIS curve progression.

CONCLUSIONS

Many promising SNPs have been identified to predict the curve progression of AIS. However, conflicting results from replication studies and different ethnic groups hamper their reliability. Convincing SNPs from multiethnic populations and functional verification are needed.

SURGICAL CORRECTION OF JUVENILE IDIOPATHIC SCOLIOSIS. OUR PATIENTS’ PERCEPTION OF THEIR QUALITY OF LIFE

ABSTRACT Objective: To report the results of our patients who underwent scoliosis correction surgery in relation to their quality of life. Introduction: Juvenile idiopathic scoliosis affects between 1 and 3% of the population during puberty. Treatment will be conservative in most cases. The goal of surgical treatment is to improve coronal and sagittal alignment. The SRS 22 questionnaire is a useful tool for assessing quality of life in these patients. Methods: A retrospective study of 22 patients submitted to corrective surgery for juvenile idiopathic scoliosis between October 2017 and January 2020 was conducted. All of them had curves greater than 45 degrees managed through instrumentation and arthrodesis. Post-surgical quality of life was assessed using the SRS 22 questionnaire. Results: The average age of our patients at the time of the intervention was 15.5 years with a predominance of female patients. The application of the SRS 22 questionnaire generated the following mean scores: pain 4.6, function 4.3, self-image 4.41, mental health 4.89, and satisfaction 5.0. Conclusions: The development of surgical techniques has allowed good results to be achieved in the treatment of scoliosis. The evaluation of our patients using the SRS 22 questionnaire reflects a good quality of life in the 5 parameters evaluated. The main limitations of this study were the small sample size and its retrospective nature. Level of Evidence III; Retrospective, longitudinal, descriptive, observational study.

The role of endocrine hormones in the pathogenesis of adolescent idiopathic scoliosis

Adolescent idiopathic scoliosis (AIS) is a common spinal deformity characterized by changes in the three-dimensional structure of the spine. It usually initiates during puberty, the peak period of human growth when the secretion of numerous hormones is changing, and it is more common in females than in males. Accumulating evidence shows that the abnormal levels of many hormones including estrogen, melatonin, growth hormone, leptin, adiponectin and ghrelin, may be related to the occurrence and development of AIS. The purpose of this review is to provide a summary and critique of the research published on each hormone over the past 20 years, and to highlight areas for future study. It is hoped that the presentation will help provide a better understanding of the role of endocrine hormones in the pathogenesis of AIS.

Idiopathic scoliosis: general characteristics and analysis of etiological theories (literature review)

Idiopathic scoliosis is a severe pathology of the musculoskeletal system that affects children and adolescents all over the world. The disease occurs in approximately 0.2-0.6% of the general population, and is the largest subgroup of spinal curvature in humans (70-90% of all known scoliosis cases). In idiopathic scoliosis, a threedimensional deformation of the vertebral column is formed, leading to the formation of a rib hump, curvature of the ribs and chest, asymmetry of the pelvis and impaired development of internal organs. The main feature of the disease is the spontaneous development of deformity during the growth of the child and the tendency to progress. Scoliosis is not only an orthopedic disease, but also a ignificant cosmetic, and, consequently, a psychological and social problem. The standard of treatment for scoliotic disease remains unchanged for a long time: observation, corset treatment and surgical correction. The prognosis for the development of pathology varies depending on the degree of deformation. The corset-therapy, hospitalization, surgery and treatment of chronic back pain have a negative impact on the psychoemotional state of children and adolescents. Despite significant advances in the methods of diagnosis of deformity, improvement of surgical treatment methods and in the study of pathogenesis, the etiological factor of pathology is still unknown. The search for the causes of idiopathic scoliosis covers almost all aspects of its possible origin: genetic, environmental, hormonal, metabolic, biochemical, neurological, and others. In recent decades, relevant theories of the development of scoliosis have been formulated, but none of the theories reveals the essence of the pathological process and has no clear justification. The greatest number of supporters is the genetic theory: genetic factors play a key role in the occurrence and development of idiopathic scoliosis. Understanding the underlying factors of the disease will enable prevention, early diagnosis, and identification of the risk groups of the patients in question.

Etiopathogenesis of adolescent idiopathic scoliosis: Review of the literature and new epigenetic hypothesis on altered neural crest cells migration in early embryogenesis as the key event

Adolescent idiopathic scoliosis (AIS) affects 2-3% of children. Numerous hypotheses on etiologic/causal factors of AIS were investigated, but all failed to identify therapeutic targets and hence failed to offer a cure. Therefore, currently there are only two options to minimize morbidity of the patients suffering AIS: bracing and spinal surgery. From the beginning of 1960th, spinal surgery, both fusion and rod placement, became the standard of management for progressive adolescent idiopathic spine deformity. However, spinal surgery is often associated with complications. These circumstances motivate AIS scientific community to continue the search for new etiologic and causal factors of AIS. While the role of the genetic factors in AIS pathogenesis was investigated intensively and universally recognized, these studies failed to nominate mutation of a particular gene or genes combination responsible for AIS development. More recently epigenetic factors were suggested to play causal role in AIS pathogenesis. Sharing this new approach, we investigated scoliotic vertebral growth plates removed during vertebral fusion (anterior surgery) for AIS correction. In recent publications we showed that cells from the convex side of human scoliotic deformities undergo normal chondrogenic/osteogenic differentiation, while cells from the concave side acquire a neuronal phenotype. Based on these facts we hypothesized that altered neural crest cell migration in early embryogenesis can be the etiological factor of AIS. In particular, we suggested that neural crest cells failed to migrate through the anterior half of somites and became deposited in sclerotome, which in turn produced chondrogenic/osteogenic-insufficient vertebral growth plates. To test this hypothesis we conducted experiments on chicken embryos with arrest neural crest cell migration by inhibiting expression of Paired-box 3 (Pax3) gene, a known enhancer and promoter of neural crest cells migration and differentiation. The results showed that chicken embryos treated with Pax3 siRNA (microinjection into the neural tube, 44 h post-fertilization) progressively developed scoliotic deformity during maturation. Therefore, this analysis suggests that although adolescent idiopathic scoliosis manifests in children around puberty, the real onset of the disease is of epigenetic nature and takes place in early embryogenesis and involves altered neural crest cells migration. If these results confirmed and further elaborated, the hypothesis may shed new light on the etiology and pathogenesis of AIS.

Genetic Variant of TBX1 Gene Is Functionally Associated With Adolescent Idiopathic Scoliosis in the Chinese Population

STUDY DESIGN

A genetic association study.

OBJECTIVE

The aim of this study was to investigate whether rs1978060 of TBX1 gene was a susceptible locus of adolescent idiopathic scoliosis (AIS) in the Chinese Han population and to better define the functional role of TBX1 in the development and progression of AIS.

SUMMARY OF BACKGROUND DATA

A recent genome-wide association study reported a novel susceptible locus in TBX1 gene, which was associated with the development of AIS in the Japanese population. However, there is a paucity of knowledge concerning the functional role of TBX1 in the Chinese AIS population.

METHODS

The SNP rs1978060 was genotyped in 1725 female AIS patients and 2600 healthy controls. Paraspinal muscle samples were collected from 30 AIS patients and 26 age-matched congenital scoliosis (CS) patients for the analysis of tissue expression. The differences of genotype and allele distributions between the patients and the controls were calculated using the χ test. The Pearson correlation analysis was carried out to investigate the relation between the expression of the PAX1 gene and the curve severity.

RESULTS

SNP rs1978060 was significantly associated with the susceptibility of AIS. Allele G of rs1978060 could significantly add to the risk of AIS with an odds ratio of 1.12. The tissue expression of TBX1 was obviously decreased in AIS patients. There was a remarkable correlation between the curve magnitude and the TBX1 expression (r = -0.519, P = 0.003).

CONCLUSION

The association between TBX1 and the susceptibility of AIS was successfully replicated in the Chinese population. Moreover, rs1978060 may be a functional variant regulating the expression of TBX1. More studies were warranted to explore the functional role of TBX1 in the onset and progression of AIS.

LEVEL OF EVIDENCE

3.

Methylation of estrogen receptor 2 (ESR2) in deep paravertebral muscles and its association with idiopathic scoliosis

Idiopathic scoliosis (IS) is one of the most common spinal disorders in adolescents. Despite many studies, the etiopathogenesis of IS is still poorly understood. In recent years, the role of epigenetic factors in the etiopathogenesis of IS has been increasingly investigated. It has also been postulated that the development and progression of the disease is related to gender and puberty, and could be associated with estrogen action. Estrogen hormones act via estrogen receptor 1 (ESR1) and estrogen receptor 2 (ESR2). It has been suggested that ESR2 expression is dependent on methylation within its gene promoter. So far, no studies have evaluated local, tissue-specific DNA methylation in patients with IS. Thus, our study aimed to analyze the methylation and expression level of ESR2 in the paraspinal muscles of the convex and concave side of the IS curvature. The methylation level within ESR2 promoter 0N, but not exon 0N, was significantly higher on the concave side of the curvature compared to the convex side. There was no significant correlation between ESR2 expression and methylation level in the promoter 0N on the convexity of thoracic scoliosis, whereas, on the concave side of the curvature, we observed a moderate negative correlation. There was no difference in the methylation levels of the ESR2 promoter and exon 0N between groups of patients with Cobb angle ≤ 70° and > 70° on the concave and convex side of the curvature. We also found no statistically significant correlation between the Cobb angle value and the mean methylation level in either the ESR2 promoter or exon 0N on the convex or concave side of the curvature. Our findings demonstrate that DNA methylation at the ESR2 promoter in deep paravertebral muscle tissue is associated with the occurrence but not with the severity of idiopathic scoliosis.

Quantitation Analysis of PCDH10 Methylation in Adolescent Idiopathic Scoliosis Using Pyrosequencing Study

STUDY DESIGN

A retrospective and comparative study.

OBJECTIVE

To evaluate the difference of DNA methylation in protocadherin10 (PCDH10) genes between adolescent idiopathic scoliosis (AIS) and normal controls, and to assess the association between DNA methylation and the etiology of AIS.

SUMMARY OF BACKGROUND DATA

The PCDH10 gene showed abnormal expression in AIS. However, the mechanism was still unclear. DNA methylation was an important epigenetic mechanism at the interface between genetics and environmental phenotype, seeming to be a suitable epigenetic mark for the abnormal expression of PCDH10 in AIS.

METHODS

There were 50 AIS patients and 50 healthy controls included in the study. The peripheral blood sample of each participant was taken. The pyrosequencing assay was used to assess the methylation status of PCDH10 promoter and real time PCR (RT-PCR) was used to detect the PCDH10 gene expression. The comparison analysis was performed using independent t test and 2-tailed Pearson coefficients was calculated for the correlation analysis.

RESULTS

The average methylation level was 4.32 ± 0.73 in AIS patients and 3.14 ± 0.97 in healthy controls (P < 0.001). The PCDH10 gene expression was 0.23 ± 0.04 in AIS patients and 0.36 ± 0.08 in normal controls (P < 0.0001). Statistically significant linear correlation was found between PCDH10 gene methylation level and Cobb angle of major curve (P < 0.001). Besides, a significant negative correlation between PCDH10 methylation and PCDH10 gene expression was found (P < 0.001).

CONCLUSION

AIS patients were associated with high DNA methylation level and low gene expression of PCDH10 gene rather than normal controls. The high methylation level indicated high Cobb angle of major curves in AIS. The abnormal DNA methylation may widely exist and serve as a potential mechanism for AIS.

LEVEL OF EVIDENCE

3.

Estrogen Receptors (ESRs) Mutations in Adolescent Idiopathic Scoliosis: A Cross-Sectional Study

BACKGROUND Adolescent idiopathic scoliosis (AIS) is the most common spinal deformity, but its etiology is unclear. Multiple genetic mutations have been reported to be associated with AIS. MATERIAL AND METHODS We enrolled a cohort of 113 surgically treated AIS patients with available parental subjects from the Peking Union Medical College Hospital. We performed whole-exome sequencing in 10 trio families and whole-genome sequencing in 103 singleton patients. Luciferase assay was used to detect the functional alterations of candidate ESR1 and ESR2 variants. RESULTS Using a de novo strategy, a missense variant in ESR1 (c.868A>G) was selected as a candidate gene for AIS. The main Cobb angle of this patient was 41° (T6-T10). Another potential pathogenic variant in ESR2 (c.236T>C) was identified. The main curve of the patient was 45° at T10-L3. The transactivation capacities of the mutated ESR1 and ESR2 protein were both significantly decreased (p=0.026 and 0.014, respectively). CONCLUSIONS Potential pathogenic variants in ESR1 and ESR2 were identified in 113 AIS patients, suggesting that genetic mutations in ESR1/2 were associated with the risk of AIS.

Association of ESRα XbaI A > G, ESRα PvuII T > C and ESRβ AlwNI T > C Polymorphisms with the Risk of Developing Adolescent Idiopathic Scoliosis: A Systematic Review and Genetic Meta-analysis

Several association studies of genes polymorphisms on estrogen receptors-α and β with respect to adolescent idiopathic scoliosis (AIS) have been published in the past two decades. However, the association with AIS, especially among different ethnic subgroups, still remains controversial. Thus, we investigated these inconclusive data by performing a meta-analysis to systematically evaluate the association.

A literature search was conducted in the PubMed, ISI Web of Science, EMBASE, SCOPUS, EBSCO, Cochrane Library, China National Knowledge Infrastructure (CNKI) and Wanfang databases until January 20, 2018. The strength of relationship was assessed using odds ratios (ORs) and 95% confidence intervals (95%CIs).

A total of 12 case–control studies with 4,304 cases of AIS and 3,123 controls met our criteria. The pooled ORs indicated that the ESRα XbaI A > G, ESRα PvuII T > C and ESRβ AlwNI T > C polymorphisms were not significantly associated with the risk of developing AIS in the overall analysis. However, we found a significant association between the ESRα XbaI A > G polymorphism and AIS under the homozygote model (GG versus AA; OR = 1.448, 95%CI: 1.052–1.993; p  = 0.023).

The present meta-analysis suggests that the ESRα XbaI A > G, ESRα PvuII T > C and ESRβ AlwNI T > C polymorphisms may not be associated with the risk of developing AIS in the overall analysis. However, ESRα XbaI A > G might have an influence on the susceptibility to develop AIS among Asians. Considering the limited sample size and ethnicity, further larger studies are needed to provide a more precise estimation of the associations.

Changes in circulating cell-free nuclear DNA and mitochondrial DNA of patients with adolescent idiopathic scoliosis

BACKGROUND

Adolescent idiopathic scoliosis (AIS) which characterized by complex three-dimensional deformity of spine has been difficult to cure because of the unknown etiopathology and uncertainty of progression. Nowadays, circulating cell-free (ccf) DNA was found to be a potential biomarker for several benign and malignant diseases. However, whether ccf DNA can be a biomarker for AIS has not been reported yet. In this study, we investigate the circulating cell-free nuclear DNA (ccf n-DNA) and mitochondrial DNA (ccf mt-DNA) concentrations in the plasma of patients with AIS and controls (CT), and the changed plasma ccf n-DNA and ccf mt-DNA levels and their association with clinical parameters were assessed.

METHODS

The plasma of peripheral blood from 69 AIS patients and 21 age-matched CT was collected for ccf DNA analysis. Quantitative PCR was used to detect ccf n-DNA and ccf mt-DNA levels, and correlation analyses between the ccf n-DNA and ccf mt-DNA levels and clinical characteristics were conducted. Receiver operator curves (ROC) were used to analyze the sensitivity and specificity of ccf n-DNA and ccf mt-DNA levels to different characteristics.

RESULTS

The plasma ccf n-DNA levels of both GAPDH and ACTB were significantly decreased in AIS patients compared with those in controls, while the plasma ccf mt-DNA levels did not changed. According to sex-related analyses, the ccf n-DNA levels in male CT-M was higher than that in female CT and male AIS, but the ccf n-DNA levels in female AIS was not significantly changed when compared with male AIS or female CT. However, the concentration of ccf mt-DNA in female AIS increased significantly when compared with male AIS. Surprisingly, Lenke type-related analyses suggested that Lenke type 1 patients had lower ccf n-DNA levels, whereas Lenke type 5 patients had higher ccf mt-DNA levels compared with those of controls. However, a lower sensitivity and specificity of AIS predicted by ccf n-DNA or ccf mt-DNA levels was observed, whether in total, by sex, or by Lenke type.

CONCLUSION

Although with no/little predictive accuracy of AIS/progressed AIS by ccf DNA levels, significantly changed plasma ccf DNA levels were observed in AIS patients compared with those in controls.

A Genetic Predictive Model Estimating the Risk of Developing Adolescent Idiopathic Scoliosis

Background:

Previous GWASs have revealed several susceptible variants associated with adolescent idiopathic scoliosis (AIS). Risk prediction based on these variants can potentially improve disease prognosis. We aimed to evaluate the combined effects of genetic factors on the development of AIS and to further develop a genetic predictive model.

Methods:

A total of 914 AIS patients and 1441 normal controls were included in the discovery stage, which was followed by the replication stage composed of 871 patients and 1239 controls. Genotyping assay was performed to analyze 10 previously reported susceptible variants, including rs678741 of LBX1, rs241215 of AJAP1, rs13398147 of PAX3, rs16934784 of BNC2, rs2050157 of GPR126, rs2180439 of PAX1, rs4940576 of BCL2, rs7593846 of MEIS1, rs7633294 of MAGI1 and rs9810566 of TNIK. Logistic regression analysis was performed to generate a risk predictive model. The predicted risk score was calculated for each participant in the replication stage.

Results:

The association of the 10 variants with AIS was successfully validated. The established model could explain approximately 7.9% of the overall variance. In the replication stage, patients were found to have a remarkably higher risk score as compared to the controls (44.2 ± 14.4 vs. 33.9 ± 12.5, p <0.001). There was a remarkably higher proportion of the risk score i.e. >40 in the patients than in the controls (59% vs. 28.9%, p <0.001).

Conclusion:

Risk predictive model based on the previously reported genetic variants has a remarkable discriminative power. More clinical and genetic factors need to be studied, to further improve the proba-bility to predict the onset of AIS.

Genetic Variants of ABO and SOX6 are Associated With Adolescent Idiopathic Scoliosis in Chinese Han Population

STUDY DESIGN

A genetic association study.

OBJECTIVE

The aim of this study was to determine whether variants of ABO, SOX6, and CDH13 are associated with the susceptibility of AIS in Chinese Han population.

SUMMARY OF BACKGROUND DATA

A recent large-scale genome-wide association study reported three novel loci in CDH13, ABO, and SOX6 genes associated with adolescent idiopathic scoliosis (AIS) in Japanese population. However, the association of these three genes with AIS in other populations remains obscure.

METHODS

The SNPs rs4513093, rs687621, and rs1455114 were genotyped in 1208 female patients and 2498 healthy controls. Samples for the expression analysis in paraspinal muscles were collected from 49 AIS and 33 congenital scoliosis (CS) patients during surgical interventions. Chi-square analysis was used to assess the difference regarding genotype and allele frequency between cases and controls. Tissue expressions of ABO, CDH13, and SOX6 were compared between AIS and CS patients by the Student t test.

RESULTS

SNPs rs4513093 of CDH13 and rs687621 of ABO were found to be significantly associated with AIS with an odds ratio of 0.8691 and 1.203, respectively. There was no significant association of rs1455114 with AIS. Moreover, AIS patients were found to have significantly increased expression of ABO. As for expression of CDH13 and SOX6, no remarkable difference was found between the two groups.

CONCLUSION

The association of CDH13 and ABO variants with AIS was successfully replicated in the Chinese Han population. More studies are warranted to explore the functional role of ABO in the development of AIS.

LEVEL OF EVIDENCE

N/A.

GENETIC ASPECTS OF IDIOPATHIC ESCOLIOSIS - A LITERATURE REVIEW

ABSTRACT The idiopathic scoliosis (IS) is the most common form of spinal deformity. The pathogenesis of IS is still poorly understood. Several studies show evidence that the genetic component is determinant to the development of IS. In this setting, a crescent focus has been placed on the identification of genes, associated genetic polymorphisms, and multiple susceptibility loci. This review highlights the genes and genetic polymorphisms currently studied, identified as influential in the genesis of IS, such as MMP-3, IL-6, type I collagen, and vitamin D and estrogen receptors. We concluded that IS remains a complex disease with a polygenic background and that genetic polymorphisms are intrinsically related to this condition. Level of evidence III; Narrative Review.

New Evidence Supporting the Role of FBN1 in the Development of Adolescent Idiopathic Scoliosis

STUDY DESIGN

A genetic association study.

OBJECTIVE

To determine whether common variants of fibrillin-1 (FBN1) and fibrillin-2 (FBN2) are associated with adolescent idiopathic scoliosis (AIS), and to further investigate to further investigate the functional role of FBN1 in the onset and progression of AIS.

SUMMARY OF BACKGROUND DATA

Previous studies have identified several rare variants in FBN1 and FBN2 that were associated with AIS. There is, however, a lack of knowledge concerning the association between common variants of FBN1 and FBN2 and AIS.

METHODS

Common variants covering FBN1 and FBN2 were genotyped in 952 patients with AIS and 1499 controls. Paraspinal muscles were collected from 66 patients with AIS and 18 patients with lumbar disc herniation (LDH) during surgical interventions. The differences of genotype and allele distributions between patients and controls were calculated using Chi-square test. The Student t test was used to compare the expression of FBN1 and FBN2 between patients with AIS and LDH. One-way analysis of variance test was used to compare the gene expression among different genotypes of the significantly associated variant. The Pearson correlation analysis was used to determine the relationship between FBN1 expression and the curve severity.

RESULTS

The common variant rs12916536 of FBN1 was significantly associated with AIS. Patients were found to have significantly lower frequency of allele A than the controls (0.397 vs. 0.450, P = 1.10 × 10) with an odds ratio of 0.81. Moreover, patients with AIS were found to have significantly lower FBN1 expression than patients with LDH (0.00033 ± 0.00015 vs. 0.00054 ± 0.00031, P = 1.70 × 10). The expression level of FBN1 was remarkably correlated with the curve severity (r = -0.352, P = 0.02). There was no significant difference of FBN1 expression among different genotypes of rs12916536.

CONCLUSION

Common variant of FBN1 is significantly associated with the susceptibility of AIS. Moreover, the decreased expression of FBN1 is significantly correlated with the curve severity of AIS. The functional role of FBN in AIS is worthy of further investigation.

LEVEL OF EVIDENCE

3.

A Genetic Variant in GPR126 Causing a Decreased Inclusion of Exon 6 Is Associated with Cartilage Development in Adolescent Idiopathic Scoliosis Population

Adolescent idiopathic scoliosis (AIS) is the most common spinal deformity disease in adolescents but its etiology and pathogenesis are still unclear. The current study aims to identify the relationship between single nucleotide polymorphisms (SNPs) of G protein-coupled receptor 126 (GPR126) gene and AIS predisposition. GPR126 contains 26 exons and alternative splicing of exon 6 and exon 25 produces 4 protein-coding transcripts. We genotyped SNPs of GPR126 gene around exon 6 and exon 25 in 131 Chinese AIS patients and 132 healthy controls and provided evidence that SNP rs41289839 G>A is strongly associated with AIS susceptibility. Linkage disequilibrium analysis suggests that rs41289839 and other AIS-related SNPs were in strong LD. Next, we demonstrated that rs41289839 G>A inhibits the inclusion of exon 6 during alternative splicing, resulting in a decreased expression level of exon 6-included transcript (GPR126-exon6ⁱⁿ) relative to the exon 6 excluded transcript (GPR126-exon6^ex) by minigene assay. Chondrogenic differentiation experiment showed that GPR126-exon6ⁱⁿ has a high expression level relative to GPR126-exon6^ex during chondrogenic differentiation of hMSCs. Our findings indicate that newly discovered SNP is related to cartilage development and may provide valuable insights into the etiology and pathogenesis of adolescent idiopathic scoliosis.

Common Variant of POC5 Is Associated With the Susceptibility of Adolescent Idiopathic Scoliosis

STUDY DESIGN

A case-control study.

OBJECTIVE

To validate the relationship between POC5 and adolescent idiopathic scoliosis (AIS) in the Chinese patients and to further investigate the functional role of POC5.

SUMMARY OF BACKGROUND DATA

Three rare functional variants in the POC5 were recently reported to be strongly associated with the disease in a large family with multiple members affected with idiopathic scoliosis. To our knowledge, the association between the mutations of POC5 and AIS remains undetermined in the Chinese population.

METHODS

Single nucleotide variants c.1336G>A, c.1286C>T, and c.1363G>C of POC5 were genotyped in 2432 patients with AIS and 2292 healthy controls using multiple ligase detection reactions. Common variants covering POC5 gene were genotyped in 1446 patients and 2080 controls. The mRNA expression of POC5 was determined in the paraspinal muscles collected from 98 patients and 28 controls. The Student t test was used to compare mRNA expression level between the patients and the controls. In addition, the POC5 expression was compared among different genotypes of the remarkably associated single nucleotide polymorphism (SNP) with analysis of variance test.

RESULTS

There was no case of mutation for the three reported variants of POC5. SNP rs6892146 was observed to have significantly different distribution of minor allele frequency in the two group (0.485 vs. 0.446, P = 0.004). The mRNA expression of POC5 was 1.5-fold higher in patients than in the controls (0.00012 ± 0.00009 vs. 0.00008 ± 0.00006, P = 0.02). Patients with genotype GG have a significantly increased expression of POC5 than those with CC (0.00014 ± 0.00007 vs. 0.00009 ± 0.00007, P = 0.03).

CONCLUSION

Common variant rs6892146 of POC5 is associated with the development of AIS in the Chinese population. Targeted regional sequencing of POC5 may help identify novel mutations associated with AIS.

LEVEL OF EVIDENCE

4.

A Replication Study for the Association of rs11190870 With Curve Severity in Adolescent Idiopathic Scoliosis in Japanese

STUDY DESIGN

Case-only study.

OBJECTIVE

The aim of this study was to confirm the association of rs11190870 with adolescent idiopathic scoliosis (AIS) severity in Japanese patients with AIS.

SUMMARY OF BACKGROUND DATA

Although the association of rs11190870 with AIS susceptibility is replicated in multiple ethnics, the association of rs11190870 with curve severity is controversial. Since the previous studies are of small, we performed a replication study using far larger number of patients than previous studies.

METHODS

A total of 1860 Japanese patients with AIS who had reached skeletal maturity or undergone surgical fusion were included in the study. We evaluated the association between rs11190870 and AIS progression for the entire group, and then for patients grouped according to a severe curve (a Cobb angle of ≥40°) or mild curve (a Cobb angle <30°). Because braces could affect the results of the present study, patients in the mild-curve group were divided according to whether or not they had worn a brace. We then evaluated associations between rs11190870 genotype and curve severity in these groups.

RESULTS

The mean Cobb angles were 54.8° ± 12.1° in the severe-curve group and 24.4° ± 4.0° in the mild-curve group. The difference in rs11190870 risk-allele frequency between the severe- and mild-curve groups was evaluated. No significant differences were observed. We then examined the association of rs11190870 risk-allele frequency between patients in the mild- and severe-curve groups using the χ test for three models, and found a marginal association between rs11190870 and curve severity in the dominant model (P = 0.035, odds ratio = 1.51).

CONCLUSION

We found no association between rs11190870 and curve severity using the criteria of previous study. However, we found a marginal association between rs11190870 and curve severity. Large-scale replication studies that consider skeletal maturity and brace history, including replication studies in other ethnic groups, would be helpful for clarifying the association.

LEVEL OF EVIDENCE

4.

Genetic Variant of PAX1 Gene Is Functionally Associated With Adolescent Idiopathic Scoliosis in the Chinese Population

STUDY DESIGN

A genetic association study.

OBJECTIVE

To investigate the association between PAX1 gene and the susceptibility of adolescent idiopathic scoliosis (AIS) in the Chinese population and to further determine the functional variant regulating PAX1 expression in patients with AIS.

SUMMARY OF BACKGROUND DATA

In a previous study an enhancer locus of PAX1 was reported to be associated with the development of AIS in the Caucasian and the Japanese population. However, there is a paucity of knowledge concerning the functional role of PAX1 in the Chinese AIS population.

METHODS

The single-nucleotide polymorphisms rs6137473 and rs169311 were genotyped in 2914 patients and 3924 controls. The differences of genotype and allele distributions between patients and controls were calculated using chi-square test. Paraspinal muscles were collected from 84 patients with AIS. The one-way analysis of variance test was used to compare the mRNA expression of PAX1 among different genotypes.

RESULTS

Both rs6137473 and rs169311 were significantly associated with the susceptibility of AIS. Allele G of rs6137473 and allele A of rs169311 can significantly add to the risk of AIS with an odds ratio of 1.17 and 1.22, respectively. Moreover, there was significant difference regarding the expression of the PAX1 between the concave side and convex side of the patients. Patients with genotype AA of rs169311 had significantly decreased expression of PAX1 than those with genotype CC. As for rs6137473, no remarkable difference of PAX1 expression was found among the three genotypes.

CONCLUSION

The association between PAX1 and the susceptibility of AIS was successfully replicated in the Chinese population. Moreover, rs169311 could be a functional variant regulating the expression of PAX1 in the paraspinal muscles of AIS. Further functional analysis is warranted for a comprehensive knowledge on the contribution of this variant to the development of AIS.

LEVEL OF EVIDENCE

3.

Fifty top-cited spine articles from mainland China: A citation analysis

Objective To identify the 50 top-cited spine articles from mainland China and to analyze their main characteristics. Methods Web of Science was used to identify the 50 top-cited spine articles from mainland China in 27 spine-related journals. The title, year of publication, number of citations, journal, anatomic focus, subspecialty, evidence level, city, institution and author were recorded. Results The top 50 articles had 29-122 citations and were published in 11 English-language journals; most (32) were published in the 2000s. The journal Spine had the largest number of articles and The Lancet had the highest impact factor. The lumber spine was the most discussed anatomic area (18). Degenerative spine disease was the most common subspecialty topic (22). Most articles were clinical studies (29); the others were basic research (21). Level IV was the most common evidence level (17). Conclusions This list indicates the most influential articles from mainland China in the global spine research community. Identification of these articles provides insights into the trends in spine care in mainland China and the historical contributions of researchers from mainland China to the international spine research field.

Polymorphisms in promoter regions of MMP-3 and IL-6 genes are not associated to adolescent idiopathic scoliosis (AIS) gender bias

STUDY DESIGN

A retrospective study in Chinese Han people.

PURPOSE

To explore whether promoter polymorphisms of matrix metalloproteinases-3 (MMP-3) (rs3025058) and interleukin-6(IL-6) (rs1800795) genes are associated to AIS gender bias.

METHODS

A total of 200 patients (100 boys and 100 girls) with AIS and 200 healthy age-matched adolescents were recruited from July 2008 to August 2013 in our scoliosis center. All AIS patients had Cobb angles larger than 20°, average 43 ± 3.6° (range 24-72°). A case-control study using genotypic technique was conducted to explore whether promoter polymorphisms of MMP-3 and IL-6 were associated to AIS gender bias. In addition, to confirm the association between gene variants of MMP-3 and IL-6 and AIS. Statistical analysis of genotype frequencies between AIS patients and normal controls was performed by X^2 test.

RESULTS

The frequency of 5A/5A genotype of MMP-3 gene in patients with AIS was higher than in controls (19% versus 9.5% p= 0.007), in the sub-divided groups depend on gender, no significant difference was found between AIS girls and boys in the frequency of 5A/5A genotype of MMP-3 (20% in girls versus 18% in boys p= 0.718). No significant difference was found between AIS and controls in the frequency of G/G genotype of IL-6 (97.5% versus 98%). In the sub-divided groups depend on gender, no significant difference was found between AIS girls and boys in the frequency of G/G genotype of the IL-6 gene (98% in girls versus 97% for boys).

CONCLUSIONS

The promoter polymorphism of the MMP-3 gene was confirmed to have an association with AIS and the promoter polymorphism of the IL-6 gene was lack of association with AIS. Besides, both gene variants of MMP-3 and IL-6 were not associated to AIS gender bias.

Etiological Theories of Adolescent Idiopathic Scoliosis: Past and Present

Adolescent idiopathic scoliosis is one of the most common spinal deformities, yet its cause is unknown. Various theories look to biomechanical, neuromuscular, genetic, and environmental origins, yet our understanding of scoliosis etiology is still limited. Determining the cause of a disease is crucial to developing the most effective treatment. Associations made with scoliosis do not necessarily point to causality, and it is difficult to determine whether said associations are primary (playing a role in development) or secondary (develop as a result of scoliosis). Scoliosis is a complex condition with highly variable expression, even among family members, and likely has many causes. These causes could be similar among homogenous groups of AIS patients, or they could be individual. Here, we review the most prevalent theories of scoliosis etiology and recent trends in research.

Genetic Polymorphism of NUCKS1 Is Associated With the Susceptibility of Adolescent Idiopathic Scoliosis

STUDY DESIGN

A genetic association study.

OBJECTIVE

The aim of this study was to investigate whether NUCKS1 is a susceptible gene of adolescent idiopathic scoliosis (AIS) in Chinese population and to further narrate its association with the clinical phenotypes.

SUMMARY OF BACKGROUND DATA

AIS is characterized by late onset of menarche and disturbed growth rhythm. Previous studies showed that NUCKS1 is associated with age at menarche and pubertal height growth.

METHODS

Single-nucleotide polymorphism rs951366 of NUCKS1 was genotyped in 972 patients and 1454 healthy controls. The differences of genotype and allele distributions between AIS patients and healthy controls were evaluated using the χ test. One-way analysis of variance test was used to compare the relationship between different genotypes and clinical features including tissue expression of NUCKS1, age at menarche, and curve magnitude.

RESULTS

Patients were found to have a significantly lower frequency of CC than the controls (5.9% vs. 10.6%, P < 0.001). Besides, the frequency of allele C was found to be remarkably lower in the patients than the controls (26.4% vs. 30.9%, P < 0.001), with an odds ratio of 0.80 (95% confidential interval = 0.71-0.91). Patients with genotype CC had a remarkably lower age at menarche than patients with genotype TT (12.1 ± 1.7 vs. 12.8 ± 2.4 years, P = 0.02). Patients with genotype TT had a remarkably lower expression level of NUCKS1 than patients with genotype CC (2.8 ± 1.9 vs. 4.3 ± 2.2, P = 0.03). As for curve magnitude, no significant difference was found among patients with different genotypes.

CONCLUSION

Patients with allele T of rs951366 can be more vulnerable to the incidence of AIS as well as a late onset of menarche. Further functional analysis is warranted for a comprehensive knowledge on the contribution of this variant to the development of AIS.

LEVEL OF EVIDENCE

4.

Lack of association between AKAP2 and the susceptibility of adolescent idiopathic scoliosis in the Chinese population

Background

Adolescent idiopathic scoliosis (AIS) is a well characterized spinal deformity that affects millions of children world-wide. The role of genetic factor in the development of AIS has been of great interest, since obvious hereditary trend has been observed in AIS families. In a recent study of Chinese population, a novel mutation of AKAP2 was observed in a family with AIS, which was believed to play a role in the aetiopathogenesis of AIS. The purpose of this study was to investigate whether genetic variants of AKAP2 are associated with the susceptibility of AIS in Chinese population.

Methods

SNV c.2645A > C of AKAP2 was genotyped in 1254 AIS patients and 1232 normal controls using allelic-specific multiple ligase detection reactions. SNPs located within 5′ untranslated regions (UTR) and 3′ UTR of AKAP2 gene were selected using Haploview (v2.6). The GWAS database composed of 961 AIS patients and 1499 controls was referred to for the genotyping information. Relative mRNA expression of AKAP2 in peripheral blood was analyzed for 33 patients and 18 age-matched controls. Comparison between the cases and controls were performed using the Student’s t test. PLINK (v1.90) was used to calculate the association of each SNP with the disease by Cochran-Armitage trend test.

Results

All the patients and the controls presented a genotype of AA in c.2645A > C of AKAP2, and there was no case of mutation in any subject. A total of 116 SNPs covering AKAP2 were analyzed, and none of these SNPs was found to have significantly different allele frequency between the cases and the controls. The mRNA expression of AKAP2 in patients was comparable with that in the controls (1.9 ± 0.8 vs. 1.8 ± 0.7, p = 0.66).

Conclusions

Our large-scale replication study of the variants in AKAP2 gene did not support its association with the susceptibility of AIS in the Chinese population. In future study, functional studies of the previously reported rare variant are warranted to clarify whether the variant can regulate the expression of AKAP2. The whole AKAP2 gene can be sequenced in larger AIS cohorts to identify potentially missing mutations.

Association Between the Estrogen Receptor Beta (ESR2) Rs1256120 Single Nucleotide Polymorphism and Adolescent Idiopathic Scoliosis: A Systematic Review and Meta-Analysis

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

The aim of this study was to assess and synthesize the current evidence on the association between the rs1256120 single nucleotide polymorphism (SNP) of the estrogen receptor beta gene (ESR2) and adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Hormonal disturbance has been postulated as a potential etiological factor in the development of AIS. As estrogen receptors are important mediators of estrogen response, mutations in these genes, including rs1256120 of ESR2, have been chosen as susceptibility candidates for AIS predisposition. The association of rs1256120 with AIS has been investigated in several recent studies, but showed conflicting evidence. We conducted a systematic review to evaluate the strength of this body of evidence and quantitative synthesis to examine sources of heterogeneity.

METHODS

This study conformed to PRISMA guidelines. Using a sensitive search strategy, PubMed (MEDLINE), EMBASE, and HuGE Literature Finder databases were searched to identify relevant studies for inclusion in the systematic review and meta-analysis. Risk of bias was assessed using a modified Newcastle-Ottawa Scale. The inverse variance model was used to calculate summary odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for the allelic (C vs. T) and genotypic comparisons. Planned subgroup and sensitivity analyses were performed.

RESULTS

Three studies were included for systematic review and meta-analysis (n = 1264 AIS cases and n=1020 controls). A null relationship was found between rs1256120 and AIS (allelic OR = 1.20, 95% CI: 0.81-1.78, P = 0.36, I = 84.9%), with the first reported association likely to be false-positive and contributing substantially to heterogeneity.

CONCLUSION

Findings from the systematic review and meta-analysis suggest that rs1256120 of ESR2 is unlikely to be a predisposing or disease-modifying genetic risk factor for AIS.

LEVEL OF EVIDENCE

2.

Association of IL-6 and MMP-3 gene polymorphisms with susceptibility to adolescent idiopathic scoliosis: a meta-analysis

Recently, several institutions have investigated the associations of MMP-3-1171 5A/6A and IL-6-174-G/C gene polymorphisms with adolescent idiopathic scoliosis (AIS), while reports from different institutions are not consistent. Therefore, we, comprehensively and systematically performed this meta-analysis to detect whether the two gene polymorphisms are correlated with AIS. From January 1994 to October 2015, all case-control studies focussed on the relationship between the two aforementioned gene polymorphisms and the susceptibility to AIS were retrieved from bibliographic databases. A total of 16 articles were found, of which five consisted of 944 cases and 1177 controls, were finally included after being assessed by two reviewers. We calculated the pooled odds ratio (OR) with 95% confidence interval (95% CI) to assess the associations. The pooled data analyses were based on allele contrast, homozygote, heterozygote, dominant and recessive models. Overall, there was no significant association of IL-6-174-G/C gene polymorphism with AIS risk. Significant association was observed in homozygote model of MMP-3-1171-5A/6A gene polymorphism (5A5A versus 6A6A: OR = 1.69, 95% CI = 1.11-2.58, P = 0.02). When stratified into Caucasian and Asian populations, positive association was found in Caucasian population (5A versus 6A: OR = 1.43, 95% CI = 1.11-1.84, P = 0.006; 5A5A versus 6A6A: OR = 1.90, 95% CI = 1.13-3.19, P = 0.015); however, there was no significant association in Asian population. The present study concluded that 5A5A genotype of MMP-3-1171 5A/6A gene polymorphism was associated with AIS, especially in Caucasian population. However, no significant association was detected between IL-6-174-G/C gene polymorphism and AIS.

Adolescent idiopathic scoliosis: current concepts on neurological and muscular etiologies

Adolescent idiopathic scoliosis (AIS) is a frequent disease but its etiology remains unknown. Gender prevalence in females is already known and there are many suggested hypotheses to explain its origin and manifestation, like associated neurologic, muscular and connective tissue disorders. Literature reports have tried to analyze disease prevalence in selected populations, possible ways of inheritance, related genes location and their polymorphisms, which may play a role in the development of the deformity. The purpose of this paper is to review and update concepts on the origin and genetic influence on AIS.

Genomic study of adolescent idiopathic scoliosis in Japan

Adolescent idiopathic scoliosis (AIS) is a common disease. It is a multi-factorial (polygenic) disease controlled by genetic and environmental factors. Studies searching for genetic factors of AIS using linkage and association analyses have been conducted and several susceptibility genes have been reported. This paper reviews the recent progress in the genome-wide association study of AIS in Japan and comments on its future task.

Estradiol via estrogen receptor beta inhibits chondrogenesis of mouse vertebral growth plate in vitro

PURPOSE

Abnormal growth of vertebral growth plate (VGP) was considered as one of the etiologic factors in adolescent idiopathic scoliosis (AIS). Previous studies described that estrogen played an important role in the pathogenesis of AIS. The present study was aimed to investigate the effect of estrogen/estrogen receptor axis on mouse VGP chondrocytes in vitro.

METHODS

Chondrocytes were isolated from mouse VGP and treated with or without 17β-estradiol (E2). Cell proliferation was measured by the cell growth rate assay. Gene expression of collagen type II and aggrecan were evaluated by real-time PCR. Expression of the proliferating cell nuclear antigen (PCNA), Sox9, and Smad4 were detected by Western blotting.

RESULTS

Estradiol inhibited the proliferation of VGP chondrocytes and the gene expression of collagen type II and aggrecan and downregulated the protein expression of PCNA, Sox9, and Smad4. In addition, the inhibitory effect of estradiol was reversed by ERβ small interfering RNA (siRNA) or PHTPP, an ERβ antagonist.

CONCLUSIONS

Estradiol via estrogen/estrogen receptor β axis inhibits the proliferation and differentiation of VGP chondrocytes, which might give some new insight into the regulatory mechanism of bone development.

Replication of Association Between 53 Single-Nucleotide Polymorphisms in a DNA-Based Diagnostic Test and AIS Progression in Chinese Han Population

STUDY DESIGN

A case-only study.

OBJECTIVE

The aim of this study was to evaluate the association of the 53 single-nucleotide polymorphisms (SNPs) in a prognostic test with curve progression in Chinese adolescent idiopathic scoliosis (AIS) patients.

SUMMARY OF BACKGROUND DATA

"ScoliScore" was the first diagnostic kit developed for curve progression of AIS in the white population. To date, there is still a paucity of validation of ScoliScore in Chinese Han population.

METHODS

A total of 670 AIS patients were included in the study, with 313 patients assigned to the nonprogression group and the other 357 patients assigned to the progression group. A panel of 53 SNPs encompassed in ScoliScore were genotyped using the PCR-based Invader assay. The allele frequencies were compared between AIS patients with progressive curve and those with nonprogressive curve.

RESULTS

SNP rs9945359 and rs17044552 are the only 2 SNPs that had significantly different allele frequencies between the 2 groups. Allele A of rs9945359 was significantly higher in the progression group than in the nonprogression group (25.7% vs 19.5%, P = 0.01), and allele A of rs17044552 was significantly lower in the progression group (11.5% vs 16.4%, P = 0.01). The odds ratio (OR) of these 2 SNPs were 1.42 [95% confidence interval (95% CI) 1.09-1.88] and 0.65 (95% CI 0.47-0.91), respectively. As for the allele frequencies of the other 51 SNPs, no significant difference was found between the 2 groups.

CONCLUSION

ScoliScore could not be able to predict the curve progression of AIS in Chinese Han population. However, the role of this test in other populations cannot be totally excluded, and additional replication studies in other ethnic groups are warranted to evaluate the significance of these SNPs.

LEVEL OF EVIDENCE

4.

The TGFB1 gene is associated with curve severity but not with the development of adolescent idiopathic scoliosis: a replication study in the Chinese population

Background

The transforming growth factor beta-1 (TGFB1) gene was recently reported to be a new susceptible gene of adolescent idiopathic scoliosis (AIS) in Russian population. This study aimed to replicate the relationship between the TGFB1 gene and the susceptibility of AIS in a Chinese population, and to further describe its association with the curve severity.

Methods

A total of 1251 female AIS patients and 994 age-matched healthy controls were included in this study. The rs1800469 of TGFB1 gene was genotyped for all participants using the PCR-based Invader assay. The differences of genotype and allele distributions between AIS patients and healthy controls were assessed using the Chi-square test. One-way ANOVA test was used to compare the mean Cobb angles among patients with different genotypes.

Results

There was no significant difference in terms of the genotype and the allele frequency between the patients and the controls. The mean Cobb angle was 34.7 ± 11.9° (range 25–61°). Case-only analysis showed that rs1800469 was significantly associated with the curve severity. Patients with genotype TT had remarkably higher curve magnitude (39.1 ± 12.8°) than those with genotype CT (34.8 ± 11.1°) or CC (32.1 ± 10.6°).

Conclusions

The TGFB1 gene may not be a predisposition gene of AIS in the Chinese population. However, it can play a role in the curve progression of AIS. Replication studies in other ethnic groups are warranted to understand the implication of TGFB1 gene in AIS.

Expression Signatures of Long Noncoding RNAs in Adolescent Idiopathic Scoliosis

Purpose. Adolescent idiopathic scoliosis (AIS), the most common pediatric spinal deformity, is considered a complex genetic disease. Causing genes and pathogenesis of AIS are still unclear. This study was designed to identify differentially expressed long noncoding RNAs (lncRNAs) involving the pathogenesis of AIS. Methods. We first performed comprehensive screening of lncRNA and mRNA in AIS patients and healthy children using Agilent human lncRNA + mRNA Array V3.0 microarray. LncRNAs expression in different AIS patients was further evaluated using quantitative PCR. Results. A total of 139 lncRNAs and 546 mRNAs were differentially expressed between AIS patients and healthy control. GO and Pathway analysis showed that these mRNAs might be involved in bone mineralization, neuromuscular junction, skeletal system morphogenesis, nucleotide and nucleic acid metabolism, and regulation of signal pathway. Four lncRNAs (ENST00000440778.1, ENST00000602322.1, ENST00000414894.1, and TCONS_00028768) were differentially expressed between different patients when grouped according to age, height, classification, severity of scoliosis, and Risser grade. Conclusions. This study demonstrates the abnormal expression of lncRNAs and mRNAs in AIS, and the expression of some lncRNAs was related to clinical features. This study is helpful for further understanding of lncRNAs in pathogenesis, treatment, and prognosis of AIS.

Investigation of the 53 Markers in a DNA-Based Prognostic Test Revealing New Predisposition Genes for Adolescent Idiopathic Scoliosis

STUDY DESIGN

A genetic association study of 53 single nucleotide polymorphisms (SNPs) with adolescent idiopathic scoliosis (AIS).

OBJECTIVE

To explore new predisposition genes of AIS in Chinese Han population SUMMARY OF BACKGROUND DATA.: A panel of 53 SNPs were reported to be associated with curve severity of AIS. However, there is still a lack of knowledge concerning the association of these SNPs with the susceptibility of AIS in the Chinese Han population.

METHODS

A gene-based association study was conducted by genotyping the 53 SNPs of a prognostic test. DNA samples of 990 female patients with AIS and 1188 age-matched healthy controls were analyzed using the polymerase chain reaction-based Invader assay. The χ test was carried out to compare the differences of genotype and allele distributions between patients with AIS and healthy controls.

RESULTS

A total of 4 SNPs were found to present significant differences in allele or genotype frequencies between the 2 groups. Compared with normal controls, patients were found to have significantly higher allele G of rs12618119 and allele A of rs9945359. Besides, patients were found to have significantly lower allele T of rs4661748 and allele C of rs4782809 than the normal controls. BIN1, CDH13, SETBP1, and SPATA21 genes could be associated with the susceptibility of AIS.

CONCLUSION

Four new predisposition genes of AIS were identified on the basis of a large-scale case-control study. Putting all these findings together, it suggests that AIS is a multifactorial disease possibly involving different pathways such as development of central neural system and bone formation. Further studies exploring more predisposition gene are essential to illustrate the etiology of AIS and to guide the prevention or prognosis of the disease.

LEVEL OF EVIDENCE

3.

Current progress in genetic research of adolescent idiopathic scoliosis

Previous genetic linkage analysis and candidate gene association analysis have unveiled dozens of variants associated with the development of adolescent idiopathic scoliosis (AIS), which however can seldom be replicated in different ethnics. Recently, two genome-wide association studies of AIS performed in Japan revealed that ladybird homeobox 1 (LBX1) gene and G protein-coupled receptor 126 (GPR126) gene could play a role in the etiopathogenesis of the disease. Since the association between these two genes and AIS were successfully validated in the Caucasian and the Chinese population, LBX1 gene and GPR126 gene were the most reliable genetic variants underling the development of AIS.

Association between Estrogen Receptor Alpha Gene Polymorphisms and Susceptibility to Idiopathic Scoliosis in Bulgarian Patients: A Case-Control Study

BACKGROUND:

The current consensus on idiopathic scoliosis maintains that it has a multifactorial etiology with genetic predisposing factors.

AIM:

Estrogen receptor alpha gene has been considered as candidate gene of idiopathic scoliosis.

MATERIAL AND METHODS:

We conducted a case-control study of Bulgarian population samples (eighty patients with idiopathic scoliosis and one hundred-sixty healthy unrelated gender-matched controls) trying to investigate the association between common genetic polymorphisms of estrogen receptor alpha and the susceptibility to idiopathic scoliosis. Molecular detection of the restriction polymorphisms XbaI and PvuII was performed by polymerase chain reaction following by restriction fragment length polymorphism. The statistical analysis was performed by Pearson’s chi-squared test.

RESULTS:

Our case-control study showed statistically significant association between the PvuII polymorphism and susceptibility to idiopathic scoliosis and curve progression. No genotype or allele of XbaI polymorphism was found to be correlated with the onset or severity of the disease.

CONCLUSIONS:

The identification of molecular markers with diagnostic and prognostic value could be useful for early detection of children at risk for the development of scoliosis and for prognosis of the risk for a rapid deformity progression. That would facilitate the therapy decisions and early stage treatment of the patient with the least invasive procedures.