Polymorphism in interleukin-6 gene is associated with bone mineral density in patients with adolescent idiopathic scoliosis

Association of IL‑6 and MMP‑3 gene polymorphisms with adolescent idiopathic scoliosis: A systematic review and meta‑analysis

The pathogenesis of adolescent idiopathic scoliosis (AIS) remains unclear. It has been found that interleukin-6 (IL-6) rs1800795 locus and matrix metalloproteinase-3 (MMP-3) rs3025058 locus gene polymorphisms may be associated with AIS susceptibility, which has been controversial and needs to be further confirmed by updated meta-analysis. The aim of the present study was to investigate the association of MMP-3 rs3025058 and IL-6 rs1800795 single nucleotide polymorphisms (SNPs) with susceptibility to AIS. All relevant articles that met the criteria were retrieved and included, and the publication dates were limited from January 2005 to December 2023. The allele frequencies and different genotype frequencies of IL-6 rs1800795 and MMP-3 rs3025058 loci in each study were extracted and statistically analyzed by ReviewManager 5.4 software, and the odds ratio (OR) and 95% confidence interval (95% CI) of different genetic models were calculated. The results of the meta-analysis showed that there was no significant association between the gene polymorphism of IL-6 rs1800795 locus and the pathogenesis of AIS. The allele 5A and genotype 5A5A of MMP-3 rs3025058 SNP were associated with AIS susceptibility (5A vs. 6A, OR=1.18; 95% CI, 1.04-1.33; 5A5A vs. 6A6A, OR=1.65; 95% CI, 1.23-2.21; and 5A5A vs. 5A6A + 6A6A, OR=1.54; 95% CI, 1.19-1.99). Results of subgroup analysis revealed that the allele 5A and genotype 5A5A of MMP-3 rs3025058 SNP were associated with AIS susceptibility in the Caucasian population, and the susceptibility of AIS was associated with the genotype 5A5A of MMP-3 rs3025058 SNP in an Asian population. There was no significant association between the gene polymorphism of IL-6 rs1800795 locus and the pathogenesis of AIS, while the allele 5A of MMP-3 rs3025058 locus was associated with the susceptibility to AIS, especially in the Caucasian population.

Potential Interaction between WNT16 and Vitamin D on Bone Qualities in Adolescent Idiopathic Scoliosis Patients and Healthy Controls

Adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal deformity that is associated with low bone mineral density (BMD). Vitamin D (Vit-D) supplementation has been suggested to improve BMD in AIS, and its outcomes may be related to genetic factors. The present study aimed to (a) investigate the synergistic effect between a low BMD-related gene (wingless-related integration site 16, WNT16) and two important Vit-D pathway genes (Vit-D receptor, VDR, and Vit-D binding protein, VDBP) on serum Vit-D and bone qualities in Chinese AIS patients and healthy adolescents, and (b) to further investigate the effect of ablating Wnt16 on the cortical bone quality and whether diets with different dosages of Vit-D would further influence bone quality during the rapid growth phase in mice in the absence of Wnt16. A total of 519 girls (318 AIS vs. 201 controls) were recruited, and three selected single-nucleotide polymorphisms (SNPs) (WNT16 rs3801387, VDBP rs2282679, and VDR rs2228570) were genotyped. The serum 25(OH)Vit-D level was significantly associated with VDBP rs2282679 alleles (OR = -4.844; 95% CI, -7.521 to -2.167, p < 0.001). Significant multi-locus models were identified by generalized multifactor dimensionality reduction (GMDR) analyses on the serum 25(OH)Vit-D level (p = 0.006) and trabecular area (p = 0.044). In the gene-edited animal study, Wnt16 global knockout (KO) and wildtype (WT) male mice were provided with different Vit-D diets (control chow (1000 IU/Kg) vs. Vit-D-deficient chow (Nil in Vit-D) vs. high-dose Vit-D chow (20,000 IU/Kg)) from 4 weeks to 10 weeks old. Wnt16 global KO mice had significantly lower serum 25(OH)Vit-D levels and higher liver Vdbp mRNA expression levels than WT mice. In addition, Wnt16 global KO mice showed a decrease in bone density, cortical thickness and cortical area compared with WT mice. Interestingly, high-dose Vit-D chow led to lower bone density, cortical thickness, and cortical area in WT mice, which were less obvious in Wnt16 global KO mice. In conclusion, WNT16 may regulate the serum 25(OH)Vit-D level and bone qualities, which might be associated with VDBP expression. Further investigations with a larger sample size and wider spectrum of scoliosis severity are required to validate our findings regarding the interaction between WNT16 and Vit-D status in patients with AIS.

Risk factors associated with low bone mineral density in children with idiopathic scoliosis: a scoping review

BACKGROUND

Children with idiopathic scoliosis (IS) have a high risk of osteoporosis and IS with low bone mineral density (BMD) are susceptible to curve progression. This review aims to explore the risk factors of low BMD in children with IS.

METHODS

Studies were retrieved from 5 databases that were published up to January 2022. Search terms are keywords in titles or abstracts, including subject headings related to "Scoliosis", "Bone Mineral Density", and "Risk Factors". Observational studies on risk factors of low BMD in children with IS were enrolled in this review. The number of studies, sample size, outcome measures, research type, endocrine, and lifestyle-related factors, gene/signal pathway, and other contents were extracted for qualitative analysis.

RESULTS

A total of 56 studies were included in this scoping review. Thirty studies involved genetic factors that may affect BMD, including the Vitamin-D receptor gene, RANK/RANKL signal pathway, the function of mesenchymal stem cells, Runx2, Interleukin-6 (IL-6), and miR-145/β-catenin pathway. Eight studies mentioned the influence of endocrine factors on BMD, and the results showed that serum levels of IL-6, leptin and its metabolites, and ghrelin in children with IS were different from the age-matched controls. In addition, there were 18 articles on lifestyle-related factors related to low BMD in children with IS, consisting of physical activity, calcium intake, Vitamin D level, and body composition.

CONCLUSIONS

Genetic, endocrine, and lifestyle-related factors might relate to low BMD and even osteoporosis in IS. To prevent osteoporosis, the effectiveness of regular screening for low BMD risk factors in children with IS needs to be investigated. Additionally, clear risk factors suggest strategies for bone intervention. Future studies should consider the effectiveness of calcium and vitamin D supplements and physical activity in BMD improvement.

Bone mineral density in children and young adults with idiopathic scoliosis: a systematic review and meta-analysis

PURPOSE

Osteoporosis is a risk factor for idiopathic scoliosis (IS) progression, but it is still unclear whether IS patients have bone mineral density (BMD) loss and a higher risk of osteoporosis than asymptomatic people. This systematic review aims to explore the differences in BMD and prevalence of osteoporosis between the IS group and the control group.

METHODS

We searched 5 health science-related databases. Studies that were published up to February 2022 and written in English and Chinese languages were included. The primary outcome measures consisted of BMD z score, the prevalence of osteoporosis and osteopenia, and areal and volumetric BMD. Bone morphometry, trabecular microarchitecture, and quantitative ultrasound measures were included in the secondary outcome measures. The odds ratio (OR) and the weighted mean difference (WMD) with a 95% confidence interval (CI) were used to pool the data.

RESULTS

A total of 32 case-control studies were included. The pooled analysis revealed significant differences between the IS group and the control group in BMD z score (WMD -1.191; 95% CI  - 1.651 to -0.732, p  <  0.001). Subgroup analysis showed significance in both female (WMD -1.031; 95% CI -1.496 to -0.566, p  <  0.001) and male participants (WMD -1.516; 95% CI -2.401 to -0.632, p  =  0.001). The prevalence of osteoporosis and osteopenia in the group with IS was significantly higher than in the control group (OR  =  6.813, 95% CI 2.815-16.489, p  <  0.001; OR 1.879; 95% CI 1.548-2.281, p  <  0.000). BMD measures by dual-energy X-ray absorptiometry and peripheral quantitative computed tomography showed a significant decrease in the IS group (all p  <  0.05), but no significant difference was found in the speed of sound measured by quantitative ultrasound between the two groups (p > 0.05).

CONCLUSION

Both the male and female IS patients had a generalized lower BMD and an increased prevalence of osteopenia and osteoporosis than the control group. Future research should focus on the validity of quantitative ultrasound in BMD screening. To control the risk of progression in IS patients, regular BMD scans and targeted intervention are necessary for IS patients during clinical practice.

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.

No Interaction Effect between Interleukin-6 Polymorphisms and Acid Ash Diet with Bone Resorption Marker in Postmenopausal Women

Background: Evidence is growing that a high-acid diet might accelerate the rate of bone loss, and gene polymorphisms such as Interleukin 6 (IL6) -174G/C and -572G/C are related to bone deterioration. However, no study of the interaction between diet and IL6 polymorphisms has been conducted among Asians. Thus, the objective of this study was to determine whether IL6 gene polymorphisms modified the association between dietary acidity and the rate of bone resorption. Methods: This cross-sectional study recruited 203 postmenopausal women (age ranged from 51 to 85 years old) in community settings. The dietary intakes of the participants were assessed using a validated interviewer-administered semi-quantitative food frequency questionnaire (FFQ), while dietary acid load (DAL) was estimated using net endogenous acid production (NEAP). Agena^® MassARRAY genotyping analysis and serum collagen type 1 cross-linked C-telopeptide (CTX1) were used to identify the IL6 genotype and as a bone resorption marker, respectively. The interactions between diet and single-nucleotide polymorphisms (SNPs) were assessed using linear regressions. Results: A total of 203 healthy postmenopausal women aged between 51 and 85 years participated in this study. The mean BMI of the participants was 24.3 kg/m². In IL6 -174 G/C, all the participants carried the GG genotype, while the C allele was absent. Approximately 40% of the participants had a high dietary acid load. Dietary acid load (B = 0.15, p = 0.031) and the IL6 -572 CC genotype group (B = 0.14, p = 0.044) were positively associated with a higher bone resorption. However, there was no moderating effect of the IL6 genetic polymorphism on the relationship between and acid ash diet and bone resorption markers among the postmenopausal women (p = 0.79). Conclusion: High consumption of an acid ash diet and the IL6 -572 C allele seem to attribute to high bone resorption among postmenopausal women. However, our finding does not support the interaction effect of dietary acidity and IL6 (-174G/C and -572G/C) polymorphisms on the rate of bone resorption. Taken together, these results have given scientific research other candidate genes to focus on which may interact with DAL on bone resorption, to enhance planning for preventing or delaying the onset of osteoporosis among postmenopausal women.

Association of IL-6 174G/C (rs1800795) and 572C/G (rs1800796) polymorphisms with risk of osteoporosis: a meta-analysis

Background

Several studies have been performed to investigate association between IL-6 174G/C (rs1800795) and 572C/G (rs1800796) gene polymorphisms and osteoporosis predisposition. However, the results were conflicting. So, we performed a meta-analysis designed to provide more reliable results for the association between IL-6 gene polymorphisms and osteoporosis.

Methods

Studies were searched using PubMed, EMBASE, the Cochrane Library and Wanfang electronic databases. The odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the association between IL-6 174G/C (rs1800795) and 572C/G (rs1800796) gene polymorphisms and osteoporosis risk. The false-positive report probabilities (FPRP) test and the venice criteria were used to assess the credibility of statistically significant associations.

Results

A total of 9 studies with 1891 osteoporosis patients and 2027 healthy controls were included in current meta-analysis. Overall, The IL-6 174G/C (rs1800795) gene polymorphism was insignificantly associated with osteoporosis vulnerability. For IL-6 572C/G (rs1800796), statistically significant elevated osteoporosis vulnerability was found in IL-6 572C/G additive model (OR = 2.25, 95% CI: 1.55–3.26), dominant model (OR = 1.42, 95% CI: 0.78–2.56) and recessive model (OR = 1.96, 95% CI: 1.36–2.83). However, the IL-6 572C/G C allele was found to be associated with reduced susceptibility to osteoporosis (OR = 0.76, 95% CI: 0.56–1.04). When excluding studies that did not conform to HWE, the results did not change significantly. Further, when we evaluated the credibility of the positive results of the current meta-analysis, we identified less credible positive results in IL-6 572C/G recessive and additive model.

Conclusion

In conclusion, IL-6 572C/G GG genotype may be associated with increased risk of osteoporosis.

Association of the IL-6 -174G > C (rs1800795) Polymorphism with Adolescent Idiopathic Scoliosis: Evidence from a Case-Control Study and Meta-Analysis

Recent epidemiological studies have identified that the -174G > C (rs1800795) polymorphism in the promoter region of the interleukin-6 ( IL-6 ) gene is associated with the risk of developing adolescent idiopathic scoliosis (AIS), but they presented inconsistent and controversial results. Thus, we performed a case-control study and meta-analysis to derive a more precise estimation of the relationship between the IL-6 -174G > C polymorphism and the risk of developing AIS. A total of 80 patients with AIS and 80 matched healthy control subjects were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. In addition, all eligible studies published up to June 2018 were identified through a search in the PubMed, EMBASE, Google Scholar, and China National Knowledge Infrastructure (CNKI) databases. We calculated the odds ratios (ORs) and 95% confidence intervals (95%CIs) to assess the association. A total of 10 eligible studies comprising 1,695 AIS cases and 2,097 healthy controls were included in the meta-analysis. The pooled data suggested a significant association between the IL-6 -174G > C polymorphism and the susceptibility to develop AIS, which was demonstrated under 4 genetic models, that is, the allelic (C versus G; OR = 0.671; 95%CI: 0.457–0.985; p  = 0.042), heterozygous (CG versus GG; OR = 0.734; 95%CI: 0.554–0.973; p  = 0.032), dominant (CC + CG versus GG; OR = 0.660; 95%CI: 0.440–0.990; p  = 0.044) and recessive models (CC versus CG + GG; OR = 0.506; 95%CI: 0.264–0.970; p  = 0.040). The stratification analysis by ethnicity revealed an increased risk of developing AIS in Caucasians, but not in Asians. The present meta-analysis, which is inconsistent with the previous meta-analysis, suggests that the IL-6 -174G > C polymorphism may increase the individual susceptibility to develop AIS, especially in Caucasians, and it could serve as a biomarker to predict the population at high risk of developing AIS.

Development of Novel Animal Model for Studying Scoliosis Using a Noninvasive Method and Its Validation through Gene-Expression Analysis

STUDY DESIGN

To induce scoliosis in young female Wistar rats using a noninvasive method and to validate this model.

PURPOSE

To induce scoliosis in a rat model noninvasively by bracing and to study the corresponding gene-expression profile in the spine and different organs.

OVERVIEW OF LITERATURE

Scoliosis involves abnormal lateral curvature of the spine, the causes of which remain unclear. In the literature, it is suggested that scoliosis is genetically heterogeneous, as there are multiple factors involved directly or indirectly in its pathogenesis. Clinical and experimental studies were conducted to understand the etiology of anatomical alterations in the spine and internal organs, as the findings could help clinicians to establish new treatment approaches.

METHODS

Twelve female Wistar rats aged 21 days were chosen for this study. Customized braces and real-time polymerase chain reaction (RT-PCR) primers for rats were designed using Primer 3 software. Radiological analysis (X-rays), histopathological studies, SYBR green, and RT-PCR analysis were performed.

RESULTS

The spines of six rats were braced in a deformed position, which resulted in a permanent structural deformity as confirmed by X-ray studies. The remaining rats were used as controls. Quantitative studies of the expression of various genes (osteocalcin, pleiotrophins, matrix metalloproteinase-2 [MMP2] and MMP9, TIMP, interleukins 1 and 6, tumor necrosis factor-α) showed their differential expression and significant upregulation (p<0.05) in different organs of scoliotic rats in comparison to those in control rats. Histopathological findings showed tissue necrosis and fibrosis in the brain, retina, pancreas, kidney, liver, and disc of scoliotic rats.

CONCLUSIONS

Bracing is a noninvasive method for inducing scoliosis in an animal model with 100% reliability and with corresponding changes in gene expression. Scoliosis does not just involve a spine deformity, but can be referred to as a systemic disease on the basis of the pathological changes observed in various internal organs.

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.

The association between interleukin 6 -174 G/C gene polymorphism and the risk of osteoporosis: A meta-analysis

Objectives

This study aimed to investigate the association between the IL6 −174 G/C gene polymorphism and the risk of osteoporosis by performing a meta-analysis.

Methods

Published literature from PubMed and Embase databases was searched for eligible publications. The following information was extracted from each study: Name of first author, year of publication, country of origin, sample size of cases and controls, and size of each allele. The combined odds ratio (ORs) and 95% confidence intervals (95%CIs) for the association between the IL6 −174 G/C gene polymorphism and the risk of osteoporosis were assessed using a random or fixed effects model. A comprehensive meta-analysis (CMA) 2.0 was used to analyse the data.

Results

Twelve studies (4923 cases/3431 controls) were included in this meta-analysis. The results indicated that IL6 −174 G/C gene polymorphism was associated with an increased (G vs C, OR 95%CI = 1.29 [1.03–1.62], p = 0.029) and decreased risk of osteoporosis (C vs G, OR 95%CI = 0.77 [0.62–0.97], p = 0.029; CC vs GG + GC, OR 95%CI = 0.58 [0.39–0.88], p = 0.010).

Conclusion

The IL6 −174 G/C gene polymorphism was shown to be positively correlated with osteoporosis risk.

Estrogen receptor gene polymorphism in patients with degenerative lumbar scoliosis

OBJECTIVE

To examine the association between development of degenerative lumbar scoliosis (DLS) and sex hormones.

METHODS

We investigated the association between DLS and estrogen receptor alpha (ERα) gene polymorphisms in 184 patients with a diagnosis of DLS, by determining the presences of the Pvu II and Xba I polymorphisms, measuring bone mineral densities at the lumbar spine (LSBMD) and femoral neck (FNBMD), and by investigating biochemical markers of bone turnover and comparing these results with those of 220 healthy normal controls.

RESULTS

Genotype frequencies in DLS patients and controls revealed a significant difference for the Pvu II polymorphism only (p = 0.0287). No significant difference was found between the DLS and control groups with respect to the Xba I polymorphism, bone mineral density (BMD), or biochemical markers. Furthermore, no significant association was observed between the Pvu II polymorphism and BMD, lumbar scoliosis, lateral listhesis, or biochemical markers in patients with DLS.

CONCLUSION

These results suggest that the ERα Pvu II polymorphism influences the prevalence of DLS.

Role of the IL-6 gene in the etiopathogenesis of idiopathic scoliosis

Scoliotic human nuclei pulposi can respond to exogenous proinflammatory stimuli by secreting increased amounts of interleukin-6 (IL-6). The G/C polymorphism of the promoter region of IL-6 gene influences levels and functional activity of the IL-6 protein. We conducted a case-control study of eighty patients with idiopathic scoliosis (IS) and one hundred sixty healthy unrelated gender-matched controls trying to investigate the association between IS and the IL-6 promoter polymorphism at -174 position (rs1800795 G/C) in Bulgarian population. Molecular detection of the IL-6 genotypes was performed by amplification followed by restriction technology. The statistical analysis was performed by Pearson's chi-squared test. Our case-control study revealed a statistically significant association between the IL-6 (-174 G/C) functional polymorphism and susceptibility to IS. In addition, a significant association between the IL-6 (-174 G/C) polymorphism and curve severity was detected. IL-6 gene could be considered as susceptibility and modifying factor of idiopathic scoliosis. 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.

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.

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.

The interleukin-6-572G/C gene polymorphism and the risk of intracranial aneurysms in a Chinese population

Interleukin-6 (IL-6) is an important proinflammatory cytokine that plays an important role in the pathogenesis of intracranial aneurysms (IAs). The aim of this study was to investigate the association between the IL-6-572G/C polymorphism and the risk of IAs in a Chinese population. The IL-6-572G/C gene polymorphisms in 220 IA cases and 220 controls were analyzed using the polymerase chain reaction-restriction fragment length polymorphism method. The IL-6-572GG (odds ratio [OR]=3.35, 95% confidence intervals [CIs]=1.65, 6.82; p=0.001) and G allele frequencies (OR=1.48, 95% CIs=1.09, 2.00; p=0.01) in the IA group were higher than those in the control group. The C allele frequencies (OR=0.68, 95% CIs=0.50, 0.92; p=0.01) were significantly lower in patients than in controls. When stratified by the site, shape, size, and the Fisher Grade of IAs, no statistically significant result was observed. This study suggested that the IL-6-572GG genotype was associated with a higher risk of IA in a Chinese population.