Replication study of the association between adolescent idiopathic scoliosis and two estrogen receptor genes

The Whole-Exome Sequencing of a Cohort of 19 Families with Adolescent Idiopathic Scoliosis (AIS): Candidate Pathways

A significant genetic involvement has been known for decades to exist in adolescent idiopathic scoliosis (AIS), a spine deformity affecting 1-3% of the world population. However, though biomechanical and endocrinological theories have emerged, no clear pathophysiological explanation has been found. Data from the whole-exome sequencing performed on 113 individuals in 19 multi-generational families with AIS have been filtered and analyzed via interaction pathways and functional category analysis (Varaft, Bingo and Panther). The subsequent list of 2566 variants has been compared to the variants already described in the literature, with an 18% match rate. The familial analysis in two families reveals mutations in the BICD2 gene, supporting the involvement of the muscular system in AIS etiology. The cellular component analysis revealed significant enrichment in myosin-related and neuronal activity-related categories. All together, these results reinforce the suspected role of the neuronal and muscular systems, highlighting the calmodulin pathway and suggesting a role of DNA-binding activities in AIS physiopathology.

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.

Single Nucleotide Polymorphisms and Adolescent Idiopathic Scoliosis: A Systematic Review and Meta-Analysis of the Literature

STUDY DESIGN

Meta-analysis.

OBJECTIVE

To determine the single nucleotide polymorphisms (SNPs) that are related to adult idiopathic scoliosis.

SUMMARY AND BACKGROUND DATA

Adolescent idiopathic scoliosis (AIS) is considered one of the most prevalent spinal diseases. Even though the cause of AIS is yet to be determined, family history and sex have shown conclusive associations. Multiple studies have indicated that AIS is more prevalent in families where at least one other first-degree relative is similarly affected, indicating a possible genetic etiology to AIS.

MATERIALS AND METHODS

Articles were collected from 3 different search engines and then processed in 2 stages for final article selection for quantitative analysis. Five different genetic models were represented to show the association between the different SNPs and AIS. The Hardy-Weinberg equilibrium was examined using Fisher exact test, with significance set at P <0.05. The final analysis paper's quality was evaluated using the Newcastle Ottawa Scale. Kappa interrater agreement was calculated to evaluate the agreement between authors.

RESULTS

The final analysis comprised 43 publications, 19412 cases, 22005 controls, and 25 distinct genes. LBX1 rs11190870 T>C and MATN-1 SNPs were associated with an increased risk of AIS in one or all of the 5 genetic models. IGF-1 , estrogen receptor alfa, and MTNR1B , SNPs were not associated with AIS in all 5 genetic models. Newcastle Ottawa Scale showed good quality for the selected articles. Cohen k = 0.741 and Kappa interrater agreement of 84% showed that the writers were in strong agreement.

CONCLUSIONS

There seem to be associations between AIS and genetic SNP. Further larger studies should be conducted to validate the results.

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.

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.

Methylation of Estrogen Receptor 1 Gene in the Paraspinal Muscles of Girls with Idiopathic Scoliosis and Its Association with Disease Severity

Idiopathic scoliosis (IS) is a multifactorial disease with epigenetic modifications. Tissue dependent and differentially methylated regions (T-DMRs) may regulate tissue-specific expression of the estrogen receptor 1 gene (ESR1). This study aimed to analyze methylation levels within T-DMR1 and T-DMR2 and its concatenation with ESR1 expression of IS patients. The study involved 87 tissue samples (deep paravertebral muscles, both on the convex and the concave side of the curve, and from back superficial muscles) from 29 girls who underwent an operation due to IS. Patient subgroups were analyzed according to Cobb angle ≤70° vs. >70°. Methylation was significantly higher in the superficial muscles than in deep paravertebral muscles in half of the T-DMR1 CpGs and all T-DMR2 CpGs. The methylation level correlated with ESR1 expression level on the concave, but not convex, side of the curvature in a majority of the T-DMR2 CpGs. The T-DMR2 methylation level in the deep paravertebral muscles on the curvature's concave side was significantly lower in patients with a Cobb angle ≤70° in four CpGs. DNA methylation of the T-DMRs is specific to muscle tissue location and may be related to ESR1 expression regulation. Additionally, the difference in T-DMR2 methylation may be associated with IS severity.

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.

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.

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.

Investigating Role of IRX Family in Development of Female Adolescent Idiopathic Scoliosis: Which One Is Real Cause?

BACKGROUND

Previous studies showed that several variants located around the IRX family may have functional roles in the development of adolescent idiopathic scoliosis (AIS). However, there was lack of knowledge concerning the target gene of the region on 5p13.3 and the role of IRX genes in the etiology of AIS. This study aimed to validate the relationship between the IRX family and AIS in a large-scale general population and to further investigate the target gene of the region, which was associated with AIS.

METHODS

SNP rs12517904 and rs117273909 were genotyped in 1323 patients and 1670 age-matched healthy controls. Paraspinal muscle was collected from 70 AIS patients and 20 congenital scoliosis patients. Student's t-test was used to compare the IRX1 expression between AIS patients and controls. The 1-way analysis of variance test was used to compare the expression of the IRX genes among different genotypes.

RESULTS

For rs12517904, patients were found to have a significantly higher frequency of allele T than the controls (37.6% vs. 34.7%, P = 0.02). Allele T can significantly add to the risk of AIS with an odds ratio of 1.14. AIS patients were found to have significantly lower IRX1 expression than the controls. Patients with genotype TT were found to have significantly lower IRX1 expression than those with genotype GG.

CONCLUSIONS

Our large-scale case control study validated that the IRX1 gene could be the disease-associated gene of AIS. The variant rs12517904 of the IRX1 gene is functionally associated with the development of AIS in the Chinese population. The role of IRX1 in the onset of AIS is worthy of further investigation.

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.

VANGL1 Is Not Associated With the Susceptibility of Adolescent Idiopathic Scoliosis in the Chinese Population

STUDY DESIGN

A case-control study.

OBJECTIVE

To replicate the association between the VANGL1 gene and the susceptibility of AIS in the Chinese population.

SUMMARY OF BACKGROUND DATA

The mutations of VANGL1 gene were recently reported to be associated with AIS in the Danish population. However, there is a lack of replication in other populations. Further analysis of the functional role of VANGL1 in AIS was warranted.

METHODS

A total of 1481 female AIS patients and 1372 age-matched healthy controls were included in this study. single nucleotide variant (SNV)s c.407T > A and c.1318T > G were genotyped using allelic-specific multiple ligase detection reactions. single nucleotide polymorphism (SNP)s covering VANGL1 gene were selected using Haploview (v2.6). The associations between theses SNPs and AIS were investigated through Cochran-Armitage trend test by PLINK (v1.90). Relative mRNA expression of VANGL1 in the paraspinal muscles was analyzed for 30 patients and 24 age-matched controls. The difference of mRNA expression level between the two groups was analyzed with the Student t test.

RESULTS

There was no case of mutation for all the subjects. A total of 22 SNPs covering VANGL1 were analyzed. All the SNPs were found to have comparable distribution of genotype and allele frequency in the cases and the controls. Moreover, there was no significant difference regarding the mRNA expression of VANGL1 in the two groups.

CONCLUSION

VANGL1 gene is not associated with AIS in the Chinese population. Replication studies in other ethnic groups are warranted to further clarify the role of the VANGL1 gene in AIS.

LEVEL OF EVIDENCE

4.

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.

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.

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.

Genome-wide association study identifies new susceptibility loci for adolescent idiopathic scoliosis in Chinese girls

Adolescent idiopathic scoliosis (AIS) is a structural deformity of the spine affecting millions of children. As a complex disease, the genetic aetiology of AIS remains obscure. Here we report the results of a four-stage genome-wide association study (GWAS) conducted in a sample of 4,317 AIS patients and 6,016 controls. Overall, we identify three new susceptibility loci at 1p36.32 near AJAP1 (rs241215, P_combined=2.95 × 10⁻⁹), 2q36.1 between PAX3 and EPHA4 (rs13398147, P_combined=7.59 × 10⁻¹³) and 18q21.33 near BCL-2 (rs4940576, P_combined=2.22 × 10⁻¹²). In addition, we refine a previously reported region associated with AIS at 10q24.32 (rs678741, P_combined=9.68 × 10⁻³⁷), which suggests LBX1AS1, encoding an antisense transcript of LBX1, might be a functional variant of AIS. This is the first GWAS investigating genetic variants associated with AIS in Chinese population, and the findings provide new insight into the multiple aetiological mechanisms of AIS.

The authors perform a genome-wide association study of adolescent idiopathic scoliosis patients of Han Chinese descent, and identify 3 new loci for disease susceptibility.

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.

Estrogen receptor 2 gene polymorphism in idiopathic scoliosis

STUDY DESIGN

A genetic association study of estrogen receptor 2 gene (ESR2) polymorphisms in idiopathic scoliosis (IS).

OBJECTIVE

To investigate association of the ESR2 polymorphisms with either predisposition to or progression of IS in Central European population.

SUMMARY OF BACKGROUND DATA

In ESR2 the rs1256120 polymorphism was described to be associated with predisposition to and severity of IS in Chinese population. This observation has not been confirmed in Japanese population. The ESR2 rs4986938 and rs1256049 polymorphisms were described to present association with breast cancer, rheumatoid arthritis, and bone mineral density, however the association with IS has not been evaluated.

METHODS

Case-control study of 248 females with IS and 243 healthy females was performed. Three single-nucleotide polymorphisms were studied using polymerase chain reaction-restriction fragments length polymorphism technique with the restriction enzymes: AlwNI (C/T rs1256120), AluI (A/G rs4986938), and RsaI (A/G rs1256049). The patients' medical history was evaluated, Cobb angle was measured and surgery rate established. The patients were analyzed in 3 subgroups according to curve progression velocity.

RESULTS

Neither the genotypes nor alleles distribution showed significant differences between patients with IS and healthy controls. There was no significant difference in genotype or allele frequency. In the AluI site polymorphism a significant difference in mean Cobb angle between genotypes was found: (AA, 31.9° ± 14.2°; AG, 43.2° ± 17.8°; and GG, 38.9° ± 19.0°), P = 0.002. There was significant difference in genotype distribution between patients with moderate (<40°) versus severe (≥40°) scoliosis, P = 0.0011; the minor allele frequency (AA) in recessive model of penetration was over-represented in patients with Cobb angle below 40°, P = 0.0075, odds ratio = 3.65.

CONCLUSION

No association between ESR2 polymorphism and predisposition to IS was found in Caucasian females. None of the previously reported associations of AlwNI site polymorphism could be confirmed. ESR2 AluI site polymorphism may be associated with curve severity.

LEVEL OF EVIDENCE

N/A.

Estrogen receptors genes polymorphisms and age at menarche in idiopathic scoliosis

Background

The age at menarche (AAM) is commonly in use in patients with IS as one of the maturity indicator suggesting deceleration of the growth velocity. The AAM was suggested to be related to predisposition and curve progression potential of IS. The late age at menarche was reported to be associated with higher prevalence of adolescent idiopathic scoliosis. The age at menarche is determined by both genetic and environmental factors as well as their interactions. Estrogen receptors 1 and 2 polymorphism were reported to be associated with AAM: in ESR1 XbaI and PvuII site polymorphism and in ESR2 AluI site polymorphism.

The purpose of the study was to investigate associations of the ESR1 and ESR2 polymorphisms with AAM in IS patients and to evaluate association of AAM with IS severity.

Methods

208 females with IS Caucasian females from Central Europe underwent clinical, radiological and genetic examinations. Four SNPs were selected XbaI (A/Grs9340799) and PvuII (C/T rs2234693) in ESR1 and AluI (A/G rs4986938) and RasI (A/G rs1256049) in ESR2. Samples were analyzed with polymerase chain reaction followed by restriction fragments length polymorphism analysis (PCR-RFLP). The age of a menarche was established during personal interview with the patients and in case of children with their parents. The Cobb angle was measured.

Results

All genotypes followed HWE. Mean AAM for patients was 154.8 ± 14.7 months (12.9 ± 1.2 years). The earliest AAM was 121 and latest 192 months. There was no statistically significant difference between AAM mean values in each genotype, for the XbaI, PvuII, AluI and RsaI site polymorphisms the p values were p = 0.7141, p = 0.9774, p = 0.7973 and p = 0.2282, respectively. Patients divided according to Cobb into mild (<30°), moderate (30°-49°) or severe (≥50°) IS revealed tendency to delay AAM: 151.9 ± 14.7; 155.2 ± 14.8 and 157.9 ± 14.0 months, respectively. There was statistical significant difference between patients with mild <30° and severe ≥50° IS, p = 0.0267.

Conclusions

In IS patients estrogen receptors polymorphisms did not show association with the AAM. Patients with severe IS form revealed delayed AAM than patients with mild IS form.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-383) contains supplementary material, which is available to authorized users.

The estrogen receptor α gene (XbaI, PvuII) polymorphisms and susceptibility to idiopathic scoliosis: a meta-analysis

STUDY DESIGN

A genetic association meta-analysis of estrogen receptor α gene (ERα) polymorphisms with idiopathic scoliosis.

OBJECTIVE

To determine whether the ERα gene polymorphisms correlate with idiopathic scoliosis. Idiopathic scoliosis represents a complex genetic trait under the influence of multiple predisposition genes. Several studies showed that single nucleotide polymorphism (SNP) in ERα was associated with idiopathic scoliosis, but the results from some studies were conflicting.

METHODS

We searched PubMed, EMBASE, and Cochrane CENTRAL databases from January 1994 to January 2014. All the case-control studies included should mainly study the relationship between XbaI A/G, PvuII T/C polymorphisms and the susceptibility of idiopathic scoliosis.

RESULTS

A total of 299 articles were found, six of which fulfilled the inclusion criteria after being assessed by two reviewers. A pooled odds ratio (OR) with 95% confidence interval (95% CI) was calculated to assess the associations. Subgroup meta-analyses were performed according to ethnicity. Overall, ERα Xbal A/G polymorphism was not associated with risk of idiopathic scoliosis (G versus A, OR 1.07, 95% CI 0.88-1.30, P = 0.51; AG versus AA, OR 1.03, 95% CI 0.89-1.21, P = 0.67; GG versus AA, OR 1.12, 95% CI 0.72-1.73, P = 0.61; AG/GG versus AA, OR 1.05, 95% CI 0.91-1.22, P = 0.49; GG versus AG/AA, OR 1.10, 95% CI 0.75-1.63, P = 0.62). ERα PvuII T/C polymorphism was also not associated with risk of idiopathic scoliosis under five models (C versus T, OR 0.93, 95% CI 0.75-1.14, P = 0.48; TC versus TT, OR 0.99, 95% CI 0.80-1.23, P = 0.93; CC versus TT, OR 1.05, 95% CI 0.80-1.39, P = 0.72; TC/CC versus TT, OR 1.01, 95% CI 0.83-1.23, P = 0.93; CC versus TC/TT, OR 1.05, 95% CI 0.82-1.33, P = 0.72).

CONCLUSION

ERα Xbal and ERα PvuII polymorphisms are not obviously associated with risk of idiopathic scoliosis.

Association Between rs11190870 Polymorphism Near LBX1 and Susceptibility to Adolescent Idiopathic Scoliosis in East Asian Population: A Genetic Meta-Analysis

STUDY DESIGN

Meta-analysis to collect all the relevant studies to date to further investigate whether or not the rs11190870 polymorphism is associated with susceptibility to adolescent idiopathic scoliosis (AIS) in East Asian population.

OBJECTIVE

To investigate whether or not the rs11190870 polymorphism is associated with susceptibility to AIS in East Asian population.

SUMMARY OF BACKGROUND DATA

To date, the single nucleotide polymorphism rs11190870 was identified as the most significant common variant in Japanese females. Three association studies conducted in Chinese Han population from Hong Kong, Yangtze River region, and Southern region of mainland China replicated the association between AIS and rs1190870. However, there is limited published data about the association of rs11190870 with AIS in East Asian population.

METHODS

A systematic search of all relevant studies published through August 2013 was conducted using the MEDLINE, EMBASE, OVID, and ScienceDirect. Single nucleotide polymorphism of rs11190870 was evaluated. The included studies were assessed in the analysis of the following allele model: T allele versus C allele for the allele-level comparison; (b) TC + TT versus CC for dominant model of T allele; (c) TT versus TC + CC for recessive model of T allele, and (d) TT versus CC for extreme genotype.

RESULTS

Four studies with 8415 total participants (2889 patients with AIS and 5526 controls), who were all East Asian population, were eligible for inclusion. We searched for genotypes T allele versus C allele, TT versus TC + CC, TC + TT versus CC, and TT versus CC in a fixed/random-effects model. The effect summary odds ratios and 95 % confidence intervals were obtained, which shows significant association between rs11190870 and AIS in East Asian populations (all genetic models P < 0.001). Subgroup analyses were conducted according to sex. The results showed a significant association between rs11190870 and AIS in female (all genetic models, P < 0.001) but not in male (all genetic models, P > 0.05).

CONCLUSION

The present meta-analysis demonstrated that the T allele of single nucleotide polymorphism rs11190870 may be a major susceptibility locus in the East Asian population with AIS, especially in female.

LEVEL OF EVIDENCE

1.

Ultrastructure of Intervertebral Disc and Vertebra-Disc Junctions Zones as a Link in Etiopathogenesis of Idiopathic Scoliosis

Background Context. There is no general accepted theory on the etiology of idiopathic scoliosis (IS). An important role of the vertebrae endplate physes (VEPh) and intervertebral discs (IVD) in spinal curve progression is acknowledged, but ultrastructural mechanisms are not well understood. Purpose. To analyze the current literature on ultrastructural characteristics of VEPh and IVD in the context of IS etiology. Study Design/Setting. A literature review. Results. There is strong evidence for multifactorial etiology of IS. Early wedging of vertebra bodies is likely due to laterally directed appositional bone growth at the concave side, caused by a combination of increased cell proliferation at the vertebrae endplate and altered mechanical properties of the outer annulus fibrosus of the adjacent IVD. Genetic defects in bending proteins necessary for IVD lamellar organization underlie altered mechanical properties. Asymmetrical ligaments, muscular stretch, and spine instability may also play roles in curve formation. Conclusions. Development of a reliable, cost effective method for identifying patients at high risk for curve progression is needed and could lead to a paradigm shift in treatment options. Unnecessary anxiety, bracing, and radiation could potentially be minimized and high risk patient could receive surgery earlier, rendering better outcomes with fewer fused segments needed to mitigate curve progression.

Lack of association between the CHL1 gene and adolescent idiopathic scoliosis susceptibility in Han Chinese: a case-control study

Background

A previous genome-wide association study (GWAS) suggested a strong association between the single nucleotide polymorphism (SNP) rs10510181 in the proximity of the gene encoding a cell adhesion molecule with homology to L1CAM (CHL1) and adolescent idiopathic scoliosis (AIS) in Caucasians. To clarify the role of CHL1 in the etiopathogenesis of AIS, we performed a case-control replication study in a Han Chinese population.

Methods

Five hundred female AIS patients between 10 and 18 years of age, as well as 500 age- and sex-matched controls were included. This study was conducted as a 2-stage case-control analysis: initial screening for the association between AIS and SNPs in and around the CHL1 gene (186 cases and 169 controls) followed by a confirmation test (314 cases and 331 controls). rs10510181 and 4 SNPs (rs2055314, rs331894, rs2272522, and rs2272524) in the CHL1 gene were selected for genotyping.

Results

Putative associations were shown between AIS and rs10510181, rs2055314, and rs2272522 in stage I. However, the associations were not confirmed in stage II. For rs10510181, the genotype frequencies were GG 28.8%, GA 46.2%, and AA 25.0% in AIS patients and GG 29.8%, GA 48.8%, and AA 21.4% in controls. No significant difference was found in genotype distribution between cases and controls (P = 0.39). Similarly, the genotype and allele distribution were comparable between case and control for rs2055314 and rs2272522.

Conclusions

There was no statistical association between polymorphisms of the CHL1 gene and idiopathic scoliosis in a Chinese population.

Understanding the Basis of Genetic Studies: Adolescent Idiopathic Scoliosis as an Example

STUDY DESIGN

A review of the general concepts of genetics studies with specific reference to adolescent idiopathic scoliosis (AIS).

OBJECTIVES

To equip the average spine surgeon with the vocabulary and understanding needed to understand the genetics of scoliosis and the approaches used to identify risk genes.

SUMMARY OF BACKGROUND DATA

Adolescent idiopathic scoliosis is a multifactorial disease. Increasing evidence from families and monozygotic twins suggests the involvement of genetic factors. An estimation of heritability also indicates a strong influence of genetics on the disease. Increasing focus has been placed on identifying genes and genetic variants associated with AIS.

REVIEW

This is a review of genes and genetic variations, the phenotype definition of AIS in genetics studies, concepts and approaches to identifying associated genes, and the evaluation of results. Different types of genetic variations are present in the genome. These variations may modulate the expression or function of protein products, which in turn alter individuals' susceptibility to disease. Identifying the variants related to AIS requires an objective and clearly defined phenotype, among which the Cobb angle is commonly used. The phenotype helps classify subjects into cases and controls. By selecting candidate genes of growth factors and hormonal receptors, which are speculated to be involved in the mechanism of disease, the variants within these genes were compared between cases and controls to identify any differences. Another approach was to use large families and inspect the co-segregation of variants and phenotypes. Recently, arrays covering the variants of the whole genome were developed and assist in high-throughput screening for associated genes.

CONCLUSIONS

Genetic factors have an important role in AIS. Deciphering the genes and genetic variants associated with AIS can improve our understanding of the mechanisms of the disease, as well as assist in designing treatment methods and preventive measures.

XbaI and PvuII polymorphisms of estrogen receptor 1 gene in females with idiopathic scoliosis: no association with occurrence or clinical form

INTRODUCTION

XbaI single nucleotide polymorphism (SNP) (A/G rs934099) in estrogen receptor 1 gene (ESR1) was described to be associated with curve severity in Japanese idiopathic scoliosis (IS) patients and in Chinese patients with both curve severity and predisposition to IS. PvuII SNP (C/T rs2234693) of ESR1 was described to be associated with the occurrence of IS in the Chinese population; however, two replication studies did not confirm the findings. The ESR1 SNPs have never been studied in Caucasian IS patients.

METHODS

Case-control study. 287 females with IS underwent clinical, radiological and genetic examinations. The patients were divided into three groups according to curve progression velocity: non-progressive IS, slowly progressive IS (progression <1° per month), and rapidly progressive IS (progression ≥1° per month). The radiological maximum Cobb angle was measured and surgery rate established. A control group consisted of 182 healthy females.

RESULTS

All results followed Hardy-Weinberg equilibrium. In the case-control study, genotype frequency in the patients did not differ for the XbaI (AA = 33.5%, AG = 49.1%, GG = 17.4%), nor for the PvuII (TT = 26.8%, TC = 50.2%, CC = 23.0%) comparing to controls (AA = 33.5%, AG = 50.5%, GG = 15.9%) and (TT = 23.1%, TC = 51.1%, CC = 25.8%), respectively, p = 0.3685, p = 0.6046. The haplotype frequency for the patients (AT = 47.1%, GC = 39.2%, AC = 8.9%, GT = 2.8%) did not differ from the controls (AT = 44.8%, GC = 37.4%, AC = 14.0%, GT = 3.8%), p = 0.0645. No difference was found either in XbaI (p = 0.8671) or PvuII (p = 0.3601) allele distribution between the patients and the controls. In the case study, there was no significant difference in genotype frequency for the non-progressive, slowly progressive, and rapidly progressive scoliosis. No difference was found in genotype or haplotype distribution for the mean maximum Cobb angle or the surgery rate.

CONCLUSIONS

No association was found between ESR1 XbaI or ESR1 PvuII SNP and idiopathic scoliosis in Caucasian females. None of the previously reported associations could be confirmed, regarding curve severity, progression or operation rate.

Indications of clinical and genetic predictors for aromatase inhibitors related musculoskeletal adverse events in Chinese Han women with breast cancer

Background

Women with breast cancer treated with aromatase inhibitors (AIs) may experience musculoskeletal symptoms that lead to discontinuation of effective therapy. The purpose of the current study is to evaluate the clinical and genetic predictors for AIs-related musculoskeletal adverse events(MS-AEs).

Methodology and Principal Findings

We recruited 436 postmenopausal Chinese Han women receiving adjuvant AIs therapy for early-stage hormone-sensitive breast cancer. Patients completed a self-administered questionnaire assessing the presence of musculoskeletal symptoms that started or worsened after initiating AIs. 27 single nucleotide polymorphisms (SNP) of ESR1, ESR2 and PGR were analyzed by Sequenom MassARRAY assays and /or PCR-based TaqMan assays.Of the 436 enrolled women, 206 cases experienced musculoskeletal symptoms.Patients who received taxane chemotherapy were more than two times more likely than other patients to have AIs-related MS-AEs. Genetic assay had showed that only two ESR1 SNPs, rs2234693 and rs9340799 were associated with AIs-related MS-AEs.TT genotype and the T allele in rs2234693 was statistically significantly lower in AIs-Related MS-AEs group than controls (P = 0.001; P = 9.49E-7). The frequency of AA genotype and the A allele in rs9340799 was higher (P = 2.20E-5; P = 3.09E-4).

Conclusions and Significance

Our results suggested that prior taxane-based chemotherapy was the clinical predictor, while rs2234693 and rs9340799 were the genetic predictors for AIs-related MS-AEs.

A replication study for association of 5 single nucleotide polymorphisms with curve progression of adolescent idiopathic scoliosis in Japanese patients

STUDY DESIGN

A genetic association study of single nucleotide polymorphisms (SNPs) previously reported to be associated with curve progression of adolescent idiopathic scoliosis (AIS).

OBJECTIVE

To determine whether the association of 5 SNPs with curve progression reported in Chinese with AIS are replicated in Japanese patients with AIS.

SUMMARY OF BACKGROUND DATA

AIS is a common spinal deformity and has a strong genetic predisposition. Predicting curve progression is important in clinical practice. The progression of AIS is reported to be associated with a number of genes. Associations with neurotrophin 3, G protein-coupled estrogen receptor, and tissue inhibitor of metalloproteinase 2 have been reported in Han Chinese with AIS; however, there has been no replication study for them.

METHODS

We recruited 2117 patients with AIS with a Cobb angle of 10° or greater of scoliosis curves. They were grouped into progression and nonprogression groups according to their scoliosis curves. Patients whose scoliotic curves were 40° or greater were included in the progression group, and those whose scoliotic curves were less than 30° and had reached skeletal maturation in the nonprogression group. We evaluated the association of 5 SNPs (rs11063714 in neurotrophin 3, rs3808351, rs10269151, and rs4266553 in G protein-coupled estrogen receptor, and rs8179090 in tissue inhibitor of metalloproteinase 2 with curve progression by comparing risk allele frequencies between the 2 groups and the mean Cobb angle for each genotype.

RESULTS

We evaluated the progression (N = 880) and nonprogression (N = 492) subjects, and their risk allele frequencies were not significantly different. The mean Cobb angle for each genotype also did not have statistical difference. We found no replication of the association on AIS curve progression in any of the SNPs.

CONCLUSION

The associations of the 5 SNPs with progression of AIS curve are not definite. Large-scale association studies based on appropriate criteria for progression would be necessary to identify SNPs associated with the curve progression.

Association between common variants near LBX1 and adolescent idiopathic scoliosis replicated in the Chinese Han population

Background

Adolescent idiopathic scoliosis (AIS) is one of the most common spinal deformities found in adolescent populations. Recently, a genome-wide association study (GWAS) in a Japanese population indicated that three single nucleotide polymorphisms (SNPs), rs11190870, rs625039 and rs11598564, all located near the LBX1 gene, may be associated with AIS susceptibility [1]. This study suggests a novel AIS predisposition candidate gene and supports the hypothesis that somatosensory functional disorders could contribute to the pathogenesis of AIS. These findings warrant replication in other populations.

Methodology/Principal Findings

First, we conducted a case-control study consisting of 953 Chinese Han individuals from southern China (513 patients and 440 healthy controls), and the three SNPs were all found to be associated with AIS predisposition. The ORs were observed as 1.49 (95% CI 1.23–1.80, P = 5.09E-5), 1.70 (95% CI 1.42–2.04, P = 1.17E-8) and 1.52 (95% CI 1.27–1.83, P = 5.54E-6) for rs625039, rs11190870 and rs11598564, respectively. Second, a case-only study including a subgroup of AIS patients (N = 234) was performed to determine the effects of these variants on the severity of the condition. However, we did not find any association between these variants and the severity of curvature.

Conclusion

This study shows that the genetic variants near the LBX1 gene are associated with AIS susceptibility in Chinese Han population. It successfully replicates the results of the GWAS, which was performed in a Japanese population.

A single-nucleotide polymorphism rs708567 in the IL-17RC gene is associated with a susceptibility to and the curve severity of adolescent idiopathic scoliosis in a Chinese Han population: a case-control study

Background

Although the pathogenesis of adolescent idiopathic scoliosis (AIS) remains controversial, genetic factors are thought to play key roles in the development of AIS. In a recent genome-wide association study, a polymorphism in the interleukin-17 receptor C (IL-17RC) gene was reported to be associated with the susceptibility to AIS, implicating IL-17RC as a novel predisposing gene for AIS. However, as this association has not been replicated in other populations, its global applicability remains unclear.

Methods

A total of 529 Chinese girls with AIS and 512 healthy age-matched controls were recruited in this case–control study from June 2007 to December 2009. Polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis was performed to detect the genotype of the single-nucleotide polymorphism (SNP) rs708567 in the IL-17RC gene. Case–control and case-only studies were performed to determine the association between the IL-17RC gene polymorphism and the susceptibility to and curve severity of AIS.

Results

The GG genotype and G allele frequencies were significantly higher in the AIS patients than in the controls (χ² test: P = 0.023 and 0.028, respectively). The risk for the GG genotype is 1.550-fold (95% CI: 1.062 - 2.261) higher than the AG genotype, and the risk for the G allele is 1.507-fold (95% CI: 1.046 - 2.172) higher than the A allele. Additionally, a subgroup of skeletally mature AIS patients (n = 241) who carried the GG genotype showed a significantly higher mean maximum Cobb angle than those carrying the AG genotype (36.01 ± 13.12° vs. 28.92 ± 7.43°, P = 0.007).

Conclusions

This study confirms the significant association between the IL-17RC gene polymorphism and the susceptibility to and curve severity of AIS in a Chinese Han population, suggesting that the IL-17RC gene is an AIS-predisposing gene in Chinese Han population.

Genetic epidemiology and heritability of AIS: A study of 415 Chinese female patients

Recent familial segregation studies supported a multifactorial genetic model for the etiology of adolescent idiopathic scoliosis (AIS). However, the extent of quantitative genetic effects, such as heritability, have not been fully evaluated. This genetic epidemiology study examined the sibling recurrent risk and heritability of AIS in first-degree relatives of 415 Chinese female patients, which is up to now the largest cohort. They were first diagnosed by community screening program and compared to 203 age-matched normal controls. Out of the total 531 sibs of AIS cases, 94 sibs had scoliosis (sibling recurrence risk = 17.7%). The prevalence of AIS among male and female sibs of an index case were 11.5% (95% CI = 7.5-15.5) and 23.0% (95% CI = 18.1-27.9), respectively. Female sibs of an index case had an increased risk of 8.9-fold (95% CI = 3.2-34.4) for developing AIS. These recurrent risks were significantly higher than the risk in the control group (p < 0.0001). Overall, heritability was estimated to be 87.5 ± 11.1%. The results confirmed the prevailing impression of strong genetic influence on the risk of AIS. Here we provided a large-scale study for the genetic aggregation estimates in an Asian population for the first time. The finding also positioned AIS among other common disease or complex traits with a high heritability.

Polygenic threshold model with sex dimorphism in adolescent idiopathic scoliosis: the Carter effect

BACKGROUND

Adolescent idiopathic scoliosis occurs between two and ten times more frequently in females than in males. The exact cause of this sex discrepancy is unknown, but it may represent a difference in susceptibility to the deformity. If this difference is attributable to genetic factors, then males with adolescent idiopathic scoliosis would need to inherit a greater number of susceptibility genes compared with females to develop the deformity. Males would also be more likely to transmit the disease to their children and to have siblings with adolescent idiopathic scoliosis. Such a phenomenon is known as the Carter effect, and the presence of such an effect would support a multifactorial threshold model of inheritance.

METHODS

One hundred and forty multiplex families in which more than one individual was affected with adolescent idiopathic scoliosis were studied. These families contained 1616 individuals, including 474 individuals with adolescent idiopathic scoliosis and 1142 unaffected relatives. The rates of transmission from the 122 affected mothers and from the twenty-eight affected fathers were calculated, and the prevalence among siblings was determined in the nuclear families of affected individuals.

RESULTS

The prevalence of adolescent idiopathic scoliosis in these multiplex families was lowest in sons of affected mothers (36%, thirty-eight of 105) and highest in daughters of affected fathers (85%, twenty-two of twenty-six). Affected fathers transmitted adolescent idiopathic scoliosis to 80% (thirty-seven) of forty-six children, whereas affected mothers transmitted it to 56% (133) of 239 children (p < 0.001). Siblings of affected males also had a significantly higher prevalence of adolescent idiopathic scoliosis (55%, sixty-one of 110) compared with siblings of affected females (45%, 206 of 462) (p = 0.04).

CONCLUSIONS

This study demonstrates the presence of the Carter effect in adolescent idiopathic scoliosis. This pattern can be explained by polygenic inheritance of adolescent idiopathic scoliosis, with a greater genetic load required for males to be affected.

The genetic epidemiology of idiopathic scoliosis

Purpose

Idiopathic scoliosis is a complex developmental syndrome defined by an abnormal structural curvature of the spine. High treatment costs, chronic pain/discomfort, and the need for monitoring at-risk individuals contribute to the global healthcare burden of this musculoskeletal disease. Although many studies have endeavored to identify underlying genes, little progress has been made in understanding the etiopathogenesis. The objective of this comprehensive review was to summarize genetic associations/linkages with idiopathic scoliosis, as well as explore the strengths and weaknesses of each study, such that it may serve as a guide for the design and interpretation of future genetic studies in scoliosis.

Methods

We searched PubMed and Human Genome Epidemiology (HuGE) Navigator using the search terms “gene and scoliosis”. Linkage or association studies published in English and available full-text were further analyzed as regards results, experimental design, and statistical approach.

Results

We identified and analyzed 50 studies matching our criteria. These consisted of 34 candidate gene studies (6 linkage, 28 association) and 16 genome-wide studies [14 pedigree-based linkage, 2 genome-wide association studies (GWAS)]. Findings involved genes related to connective tissue structure, bone formation/metabolism, melatonin signaling pathways, puberty and growth, and axon guidance pathways. Variability in results between studies suggested ethnic and/or genetic heterogeneity.

Conclusions

The major difficulty in idiopathic scoliosis research is phenotypic and genetic heterogeneity. Genetic research was overrepresented by underpowered studies. The use of biological endophenotypes, as well as restricted clinical definitions, may help to partition variation and increase the power of studies to detect or confirm an effect.

SNP rs11190870 near LBX1 is associated with adolescent idiopathic scoliosis in southern Chinese

A study was conducted to validate the most significant single nucleotide polymorphism (SNP) from a genome-wide association study of Japanese adolescent idiopathic scoliosis (AIS) patients in an independent southern Chinese population. In total, 300 AIS patients fulfilled the clinical criteria and 788 controls with MRI scans of the spine were included in the replication study. We employed case-control analysis to study the association of SNP rs11190870 near LBX1 (ladybird homeobox 1) with AIS in a southern Chinese population. The results suggest that SNP rs11190870 is significantly associated with AIS (P=9.1 × 10(-10); odds ratio=1.85; 95% confidence interval=1.52-2.25). The results of this study confirm that SNP rs11190870 is associated with AIS.

Lack of association between adolescent idiopathic scoliosis and previously reported single nucleotide polymorphisms in MATN1, MTNR1B, TPH1, and IGF1 in a Japanese population

Adolescent idiopathic scoliosis (AIS) is a spinal deformity most commonly arising in apparently healthy girls around puberty. AIS has a strong genetic predisposition. Several genetic associations between AIS and single nucleotide polymorphisms (SNPs) have been reported; common SNPs in the genes for matrilin 1 (MATN1), melatonin receptor 1B (MTNR1B), tryptophan hydroxylase 1 (TPH1), and insulin-like growth factor 1 (IGF1) are reported to be associated with AIS in Chinese. However, these associations have not been replicated so far. To confirm the associations, we compared these SNPs with AIS predisposition and curve severity in a population of Japanese females consisting of 798 AIS patients and 1,239 controls. All the subjects were genotyped using the PCR-based Invader assay. We found no association of any of the SNPs with AIS predisposition or curve severity. Considering the statistical power and sample size of the present study, we concluded that these SNPs are not associated with either AIS predisposition or curve severity in Japanese.