Association between genetic determinants of peak height velocity during puberty and predisposition 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.

Advances in epigenetic research of adolescent idiopathic scoliosis and congenital scoliosis

Scoliosis is a three-dimensional structural deformity of the spine; more than 80% of scoliosis has no specific pathogenesis but is understood to be closely related to genetic, hormonal, and environmental factors. In recent years, the epigenetic alterations observed in scoliosis have been analyzed in numerous studies to determine the pathogenesis and progression of this condition, however, there is currently no comprehensive review of the epigenetic factors to date. We searched PubMed, Embase, and Web of Science databases for relative studies without language and date restrictions in March 2023. Twenty-five studies were included in this review and analyzed from the four main aspects of epigenetic alteration: DNA methylation, non-coding RNAs, histone modifications, and chromatin remodeling. The relationship between DNA methylation, non-coding RNAs, and scoliosis was considerably reported in the literature, and the corresponding related signaling pathways and novel biomarkers observed in scoliosis provide insights into innovative prevention and treatment strategies. However, the role of histone modifications is rarely reported in scoliosis, and few studies have investigated the relationship between scoliosis and chromatin remodeling. Therefore, these related fields need to be further explored to elucidate the overall effects of epigenetics in scoliosis.

Mesenchyme-specific loss of Dot1L histone methyltransferase leads to skeletal dysplasia phenotype in mice

Chromatin modifying enzymes play essential roles in skeletal development and bone maintenance, and deregulation of epigenetic mechanisms can lead to skeletal growth and malformation disorders. Here, we report a novel skeletal dysplasia phenotype in mice with conditional loss of Disruptor of telomeric silencing 1-like (Dot1L) histone methyltransferase in limb mesenchymal progenitors and downstream descendants. Phenotypic characterizations of mice with Dot1L inactivation by Prrx1-Cre (Dot1L-cKO^Prrx1) revealed limb shortening, abnormal bone morphologies, and forelimb dislocations. Our in vivo and in vitro data support a crucial role for Dot1L in regulating growth plate chondrocyte proliferation and differentiation, extracellular matrix production, and secondary ossification center formation. Micro-computed tomography analysis of femurs revealed that partial loss of Dot1L expression is sufficient to impair trabecular bone formation and microarchitecture in young mice. Moreover, RNAseq analysis of Dot1L deficient chondrocytes implicated Dot1L in the regulation of key genes and pathways necessary to promote cell cycle regulation and skeletal growth. Collectively, our data show that early expression of Dot1L in limb mesenchyme provides essential regulatory control of endochondral bone morphology, growth, and stability.

The Effectiveness of Progressive and Traditional Coaching Strategies to Improve Sprint and Jump Performance Across Varying Levels of Maturation within a General Youth Population

Literature pertaining to youth development has identified the importance of understanding the physical, intellectual and emotional needs of adolescents prior to, during, and after their peak height velocity (PHV) period. The purpose of this study was to compare the use of a ‘traditional’ and ‘progressive’ coaching style to train a general male youth population to improve sprint and jump performances whilst assessing enjoyment to comment on long-term application. Maximal sprint times, sprint kinematics, unilateral jump distances and repetitive tuck jump scores were measured alongside anthropometric variables to characterise performance. The results revealed significant (p < 0.05) pre/post differences in anthropometric variables across all maturation groups, and each of the maturational levels displayed a tendency to favor a particular coaching or control condition. Pre-PHV groups responded most effectively to the progressive style of coaching, displaying improvements in horizontal jump performances, and −0.7% to −2.7% improvements in all sprint times, despite also showing the largest increase in tuck jump scores (25.8%). The circa-PHV group produced their greatest improvements in the traditional intervention, as displayed through significant improvements (p < 0.05) in 20-m sprint times and dominant-leg horizontal jump performance, whilst also revealing the greatest deterioration in tuck jump scores (14.2%). Post-PHV displayed the greatest improvements in the control setting, suggesting that the natural benefits gained through adolescent development were greater than the influence of the training interventions. In conclusion, the results suggest that matching coaching strategies and delivery techniques to the period of biological maturation may have implications for both performance and athlete safety.

Suv39h1 promotes facet joint chondrocyte proliferation by targeting miR-15a/Bcl2 in idiopathic scoliosis patients

Background

Idiopathic scoliosis (IS) is a complex disease with an unclear etiology, and the worldwide prevalence is approximately 2–3%. As an important link between environmental factors and phenotypic differences, epigenetic changes, such as lncRNA, miRNA, and DNA methylation, have recently been reported to be associated with the development of IS. However, the correlation between histone methylation, another classical epigenetic mechanism, and IS has not been determined. In this study, we investigated the morphological changes, alterations in the levels of histone methylation, and cell proliferation-related pathway in inferior facet joint cartilage in 11 IS patients and 10 comparable controls.

Results

Compared with the control group, narrowed facet joint cartilage but increased proliferative chondrocytes and upregulated collagen type II (COL2A1) and B-cell lymphoma-2 (Bcl2) were observed in IS patients. Additionally, tri-methylation levels of H3K9 (H3K9me3) rather than other lysine sites were significantly increased in IS patients, coinciding with the upregulation of its specific enzyme, suppressor of variegation 3-9, drosophila homolog of 1 (SUV39H1). In addition, Bcl2-targeted miR-15a was downregulated in IS patients, and the level of H3K9me3 in the promoter region of the miR-15a host gene was remarkably increased in IS patients compared with the control group. Moreover, overexpressing SUV39H1 in ATDC5 cells with increased H3K9me3 levels led to similar changes, with increased expression of COL2A1 and Bcl2, decreased expression of miR-15a, and increased cell proliferation.

Conclusions

Thus, our study suggests that increased chondrocyte proliferation occurs in the facet joint cartilage of IS patients compared with the control group and may be promoted by the elevated levels of H3K9me3 and SUV39H1, which regulate the miR-15a/Bcl2 pathway. This dysregulation of chondrocyte proliferation could result in abnormal spinal growth and may additionally participate in the development and progression of IS.

Electronic supplementary material

The online version of this article (10.1186/s13148-019-0706-1) contains supplementary material, which is available to authorized users.

Rare variant of HSPG2 is not involved in the development of adolescent idiopathic scoliosis: evidence from a large-scale replication study

BACKGROUND

Rare variants of HSPG2 have recently been reported to function as a potential contributor to the susceptibility of adolescent idiopathic scoliosis (AIS) in the Caucasians. A replication study in the different population is warranted to validate the role of HSPG2 in AIS. The aim of this study was to determine the association between HSPG2 and AIS in the Chinese patients and to further investigate its influence on the phenotype of the patients.

METHODS

SNVs p.Asn786Ser of HSPG2 was genotyped in 1752 patients and 1584 normal controls using multiple ligase detection reactions. The mRNA expression of HSPG2 in the paraspinal muscles was quantified for 90 patients and 26 controls. The The Student's t test was used to analyze the inter-group comparison of the HSPG2 expression. The relationship between the HSPG2 expression and the curve magnitude of the patients was analyzed by the Pearson correlation analysis.

RESULTS

No case of mutation in the reported SNV p.Asn786Ser of HSPG2 was found in our cohort. The mRNA expression of HSPG2 in patients was comparable with that in the controls (0.0016 ± 0.0013 vs. 0.0019 ± 0.0012, p = 0.29). 42 patients with curve magnitude > 60 degrees were assigned to the severe curve group. The other 58 patients were assigned to the moderate curve group. These two groups were found to have comparable HSPG2 expression (0.0015 ± 0.0011 vs. 0.0017 ± 0.0014, p = 0.57). And there was no remarkable correlation between the expression level of HSPG2 and the curve severity (r = 0.131, p = 0.71).

CONCLUSIONS

HSPG2 gene was not associated with the susceptibility or the phenotypes of AIS in the Chinese population. The whole HSPG2 gene can be sequenced in more AIS patients to identify potentially causative mutations.

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.

Modelling height in adolescence: a comparison of methods for estimating the age at peak height velocity

BACKGROUND

Controlling for maturational status and timing is crucial in lifecourse epidemiology. One popular non-invasive measure of maturity is the age at peak height velocity (PHV). There are several ways to estimate age at PHV, but it is unclear which of these to use in practice.

AIM

To find the optimal approach for estimating age at PHV.

SUBJECTS AND METHODS

Methods included the Preece & Baines non-linear growth model, multi-level models with fractional polynomials, SuperImposition by Translation And Rotation (SITAR) and functional data analysis. These were compared through a simulation study and using data from a large cohort of adolescent boys from the Christ's Hospital School.

RESULTS

The SITAR model gave close to unbiased estimates of age at PHV, but convergence issues arose when measurement error was large. Preece & Baines achieved close to unbiased estimates, but shares similarity with the data generation model for our simulation study and was also computationally inefficient, taking 24 hours to fit the data from Christ's Hospital School. Functional data analysis consistently converged, but had higher mean bias than SITAR. Almost all methods demonstrated strong correlations (r > 0.9) between true and estimated age at PHV.

CONCLUSIONS

Both SITAR or the PBGM are useful models for adolescent growth and provide unbiased estimates of age at peak height velocity. Care should be taken as substantial bias and variance can occur with large measurement error.

Genome-wide association study identifies novel susceptible loci and highlights Wnt/beta-catenin pathway in the development of adolescent idiopathic scoliosis

The genetic architecture of adolescent idiopathic scoliosis (AIS) remains poorly understood. Here we present the result of a 4-stage genome-wide association study composed of 5,953 AIS patients and 8,137 controls. Overall, we identified three novel susceptible loci including rs7593846 at 2p14 near MEIS1 (Pcombined = 1.19 × 10-13, OR = 1.21, 95% CI = 1.10-1.32), rs7633294 at 3p14.1 near MAGI1 (Pcombined = 1.85 × 10-12, OR = 1.20, 95% CI = 1.09-1.32), and rs9810566 at 3q26.2 near TNIK (Pcombined = 1.14 × 10-11, OR = 1.19, 95% CI = 1.08-1.32). We also confirmed a recently reported region associated with AIS at 20p11.22 (Pcombined = 1.61 × 10-15, OR = 1.22, 95% CI = 1.12-1.34). Furthermore, we observed significantly asymmetric expression of Wnt/beta-catenin pathway in the bilateral paraspinal muscle of AIS patients, including beta-catenin, TNIK, and LBX1. This is the first study that unveils the potential role of Wnt/beta-catenin pathway in the development of AIS, and our findings may shed new light on the etiopathogenesis of AIS.

Genetics and pathogenesis of idiopathic scoliosis

Idiopathic scoliosis (IS), the most common spinal deformity, affects otherwise healthy children and adolescents during growth. The aetiology is still unknown, although genetic factors are believed to be important. The present review corroborates the understanding of IS as a complex disease with a polygenic background. Presumably IS can be due to a spectrum of genetic risk variants, ranging from very rare or even private to very common. The most promising candidate genes are highlighted.

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.

Association between single nucleotide polymorphisms of DOT1L gene and risk of knee osteoarthritis in a Chinese Han population

To investigate associations between single nucleotide polymorphisms rs12982744 and rs12459350 in the DOT1L gene and knee osteoarthritis (OA) susceptibility in a Chinese Han population. DOT1L rs12982744 and rs12459350 polymorphisms were genotyped in patients with knee OA and age- and sex-matched OA-free controls from a Chinese Han population. A total of 605 patients with knee OA and 615 controls were enrolled in the study. GC and CC genotypes of rs12982744, and variant C, were associated with a significantly increased risk of knee OA. On stratification analysis, the association between the risk of OA and rs12982744 GC heterozygotes compared with GG homozygotes was stronger in females and those aged >65 years. In contrast, the GA and AA genotypes of rs12459350 were not significantly associated with the risk of knee OA, even after further stratification analysis according to age or sex. Our results showed that DOT1L rs12982744 G to C change and variant C genotype may contribute to knee OA risk in a Chinese Han population.

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 of GPR126 gene polymorphism with adolescent idiopathic scoliosis in Chinese populations

Idiopathic scoliosis is the most common pediatric spinal deformity affecting 1% to 3% of the population, and adolescent idiopathic scoliosis (AIS) accounts for approximately 80% of these cases; however, the etiology and pathogenesis of AIS are still uncertain. The current study aims to identify the relationship between G protein-coupled receptor 126 (GPR126) gene and AIS predisposition, to identify the relationship between the genotypes of the GPR126 SNPs and the clinical phenotypes of AIS. We conducted a case-control study and genotyped twenty SNPs of GPR126 gene including ten exonic SNPs and ten intronic polymorphisms in 352 Chinese sporadic AIS patients and 149 healthy controls. We provided evidence for strong association of three intronic SNPs of the GPR126 gene with AIS susceptibility: rs6570507 A > G (p =0 .0035, OR = 1.729), rs7774095 A > C (p = 0.0078, OR = 1.687), and rs7755109 A > G (p = 0.0078, OR = 1.687). However, we did not identify any significant association between ten exonic SNPs of GPR126 and AIS. Linkage disequilibrium analysis indicated that rs7774095 A > C and rs7755109 A > G could be parsed into one block. The association between the intronic haplotype and AIS was further confirmed in an independent population with 110 AIS individuals and 130 healthy controls (p = 0.046, OR = 1.680). Furthermore, molecular mechanisms underlying intronic SNP regulation of GPR126 gene were studied. Although intronic SNPs associated with AIS didn't influence GPR126 mRNA alternative splicing, there was a strong association of rs7755109 A > G with decreased GPR126 mRNA level and protein levels. Our findings indicate that genetic variants of GPR126 gene are associated with AIS susceptibility in Chinese populations. The genetic association of GPR126 gene and AIS might provide valuable insights into the pathogenesis of adolescent idiopathic scoliosis.

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.