Validation of DNA-based prognostic testing to predict spinal curve progression in adolescent idiopathic scoliosis

Towards a comprehensive diagnostic assay for scoliosis

Adolescent idiopathic scoliosis (AIS) is one of the most common childhood deformities worldwide, characterized by a 3D spinal deformity with unknown cause, and represents both an immediate medical challenge and a chronic condition affecting individuals throughout their lives. The standard of care for scoliosis has not changed in any significant manner in decades. Patients today are treated in a substantially similar manner to those 20 or 30 years ago: observation, bracing and spinal surgery as last resort. Recent progress allow the identification of potential candidate genes, but the function of these still remains elusive and further efforts should be made to connect the predisposing genetic background to the physiopathology. To overcome that situation, we developed functional and biochemical assays that represent promising alternatives. They can help to understand the physiopathology of AIS and direct genetic studies, but more importantly they will contribute to an improved stratification of AIS patients, and thus lead to accurate personalized diagnoses, prognoses and treatment strategies.

Genetic aspects of congenital and idiopathic scoliosis

Congenital and idiopathic scoliosis represent disabling conditions of the spine. While congenital scoliosis (CS) is caused by morphogenic abnormalities in vertebral development, the cause(s) for idiopathic scoliosis is (are) likely to be varied, representing alterations in skeletal growth, neuromuscular imbalances, disturbances involving communication between the brain and spine, and others. Both conditions are characterized by phenotypic and genetic heterogeneities, which contribute to the difficulties in understanding their genetic basis that investigators face. Despite the differences between these two conditions there is observational and experimental evidence supporting common genetic mechanisms. This paper focuses on the clinical features of both CS and IS and highlights genetic and environmental factors which contribute to their occurrence. It is anticipated that emerging genetic technologies and improvements in phenotypic stratification of both conditions will facilitate improved understanding of the genetic basis for these conditions and enable targeted prevention and treatment strategies.

Does ScoliScore provide more information than traditional clinical estimates of curve progression?

STUDY DESIGN

Retrospective study comparing ScoliScore and clinical risk estimates.

OBJECTIVE

The purpose of this study was to compare risk stratification between ScoliScore and traditional clinical estimates to determine whether ScoliScore provides unique information.

SUMMARY OF BACKGROUND DATA

ScoliScore is a genetic prognostic test designed to evaluate the risk of curve progression in skeletally immature patients with adolescent idiopathic scoliosis with Cobb angles of 10° to 25°. Clinicians are currently trying to better understand the role this test may play in guiding clinical decision making because current standards of curve progression are largely based on radiographical markers, such as curve magnitude and bone age.

METHODS

Ninety-one patients who received ScoliScore testing at our center and met study inclusion criteria were identified. Patients were given a "clinical risk" level using their Risser sign and Cobb angle. Assigned clinical risk levels were compared with the ScoliScore risk levels reported by the manufacturer's scoring algorithm.

RESULTS

ScoliScore risk distribution in our population was 36% low risk, 55% intermediate risk, and 9% high risk. This compares with 2%, 51%, and 47%, respectively, for comparable clinical risk groupings. Only 25% of patients were in the same risk category for both systems. There were no significant correlations between ScoliScore and age, race, menarcheal status, Risser sign, or sex. There was a positive correlation between the Cobb angle and the ScoliScore (r = 0.581, P < 0.001). Cobb angle remained significant in the multivariate regression model (P < 0.001), and Cobb angle was found to account for 33.3% of ScoliScore's variance.

CONCLUSION

Only Cobb angle showed significant correlation with ScoliScore among the socioclinical variables studied. The risk distribution of the 2 risk estimation systems examined differed markedly: ScoliScore predicted nearly 16 times more low-risk patients and more than 5 times fewer high-risk patients. This demonstrates that ScoliScore provides unique information to traditional predictors of curve progression, advancing our understanding of the role of ScoliScore in the clinical setting.

A new risk classification rule for curve progression in adolescent idiopathic scoliosis

BACKGROUND CONTEXT

Prognostic factors for curve progression of adolescent idiopathic scoliosis (AIS) have been reported previously. There is only one existing rule that classifies AIS patients into two groups by a curvature of 25°.

PURPOSE

This study aimed to develop a more refined risk classification rule for AIS.

STUDY DESIGN

This was a retrospective cohort study.

PATIENT SAMPLE

We examined 2,308 untreated AIS patients, aged 10 years and older, who had a Risser sign of 2 and lesser and a curvature less than 30° at presentation.

OUTCOME MEASURES

Outcome was taken as the time to progression to 30°.

METHODS

Patients' clinical parameters were analyzed by Classification and Regression Tree analysis.

RESULTS

The new classification rule identified four risk groups of curve progression. Patients with a curvature of 26° and more and less than 18° constituted the highest and lowest risk groups, respectively. The two intermediate groups were identified by the age (11.3 years), menarcheal status, and body height (154 cm).

CONCLUSIONS

The risk classification rule only uses information at the first presentation and can aid physicians in deriving an efficient management.

Orthogenomics: an update

The study of genomics in orthopaedics has considerably lagged behind such study in other medical disciplines. Seminal work from other lines of medical research demonstrates the importance of genomic information in the evolution of personalized medicine. Common techniques for studying genome-phenotype associations include single nucleotide polymorphism, haplotype, and quantitative trait loci analysis. The few genome-based studies in major orthopaedic and related conditions have focused on osteoporosis, osteoarthritis, neuropathy and nerve compression, spinal deformity, trauma and inflammatory response, and pain and analgesia. The nascent field of orthogenomics, newly defined here as the application of genomic study to orthopaedic practice, has produced findings that could affect the practice of orthopaedics. However, more work is required, and the findings must be distilled and harnessed into applicable and achievable steps to improve clinical orthopaedic practice.

2011 SOSORT guidelines: Orthopaedic and Rehabilitation treatment of idiopathic scoliosis during growth

BACKGROUND

The International Scientific Society on Scoliosis Orthopaedic and Rehabilitation Treatment (SOSORT), that produced its first Guidelines in 2005, felt the need to revise them and increase their scientific quality. The aim is to offer to all professionals and their patients an evidence-based updated review of the actual evidence on conservative treatment of idiopathic scoliosis (CTIS).

METHODS

All types of professionals (specialty physicians, and allied health professionals) engaged in CTIS have been involved together with a methodologist and a patient representative. A review of all the relevant literature and of the existing Guidelines have been performed. Documents, recommendations, and practical approach flow charts have been developed according to a Delphi procedure. A methodological and practical review has been made, and a final Consensus Session was held during the 2011 Barcelona SOSORT Meeting.

RESULTS

The contents of the document are: methodology; generalities on idiopathic scoliosis; approach to CTIS in different patients, with practical flow-charts; literature review and recommendations on assessment, bracing, physiotherapy, Physiotherapeutic Specific Exercises (PSE) and other CTIS. Sixty-five recommendations have been given, divided in the following topics: Bracing (20 recommendations), PSE to prevent scoliosis progression during growth (8), PSE during brace treatment and surgical therapy (5), Other conservative treatments (3), Respiratory function and exercises (3), Sports activities (6), Assessment (20). No recommendations reached a Strength of Evidence level I; 2 were level II; 7 level III; and 20 level IV; through the Consensus procedure 26 reached level V and 10 level VI. The Strength of Recommendations was Grade A for 13, B for 49 and C for 3; none had grade D.

CONCLUSION

These Guidelines have been a big effort of SOSORT to paint the actual situation of CTIS, starting from the evidence, and filling all the gray areas using a scientific method. According to results, it is possible to understand the lack of research in general on CTIS. SOSORT invites researchers to join, and clinicians to develop good research strategies to allow in the future to support or refute these recommendations according to new and stronger evidence.

Adolescent idiopathic scoliosis (AIS), environment, exposome and epigenetics: a molecular perspective of postnatal normal spinal growth and the etiopathogenesis of AIS with consideration of a network approach and possible implications for medical therapy

Genetic factors are believed to play an important role in the etiology of adolescent idiopathic scoliosis (AIS). Discordant findings for monozygotic (MZ) twins with AIS show that environmental factors including different intrauterine environments are important in etiology, but what these environmental factors may be is unknown. Recent evidence for common chronic non-communicable diseases suggests epigenetic differences may underlie MZ twin discordance, and be the link between environmental factors and phenotypic differences. DNA methylation is one important epigenetic mechanism operating at the interface between genome and environment to regulate phenotypic plasticity with a complex regulation across the genome during the first decade of life. The word exposome refers to the totality of environmental exposures from conception onwards, comprising factors in external and internal environments. The word exposome is used here also in relation to physiologic and etiopathogenetic factors that affect normal spinal growth and may induce the deformity of AIS. In normal postnatal spinal growth we propose a new term and concept, physiologic growth-plate exposome for the normal processes particularly of the internal environments that may have epigenetic effects on growth plates of vertebrae. In AIS, we propose a new term and concept pathophysiologic scoliogenic exposome for the abnormal processes in molecular pathways particularly of the internal environment currently expressed as etiopathogenetic hypotheses; these are suggested to have deforming effects on the growth plates of vertebrae at cell, tissue, structure and/or organ levels that are considered to be epigenetic. New research is required for chromatin modifications including DNA methylation in AIS subjects and vertebral growth plates excised at surgery. In addition, consideration is needed for a possible network approach to etiopathogenesis by constructing AIS diseasomes. These approaches may lead through screening, genetic, epigenetic, biochemical, metabolic phenotypes and pharmacogenomic research to identify susceptible individuals at risk and modulate abnormal molecular pathways of AIS. The potential of epigenetic-based medical therapy for AIS cannot be assessed at present, and must await new research derived from the evaluation of epigenetic concepts of spinal growth in health and deformity. The tenets outlined here for AIS are applicable to other musculoskeletal growth disorders including infantile and juvenile idiopathic scoliosis.

Heritability of scoliosis

PURPOSE

To estimate the heritability of scoliosis in the Swedish Twin Registry.

METHODS

Self-reported data on scoliosis from 64,578 twins in the Swedish Twin Registry were analysed. Prevalence, pair- and probandwise concordances and tetrachoric correlations in mono- and dizygotic same-sex twins were calculated. The relative importance of genetic variance, i.e. the heritability, and unique and shared environmental variance was estimated using structural equation modelling in Mx software. In addition, all twins in the twin registry were matched against the Swedish Inpatient Register on the primary diagnosis idiopathic scoliosis.

RESULTS

The prevalence of scoliosis was 4%. Pair- and probandwise concordance was 0.11/0.17 for mono- and 0.04/0.08 for same-sex dizygotic twins. The tetrachoric correlation (95% CI) was 0.41 (0.33-0.49) in mono- and 0.18 (0.09-0.29) in dizygotic twins. The most favourable model in the Mx analyses estimated the additive genetic effects (95% CI) to 0.38 (0.18-0.46) and the unique environmental effects to 0.62 (0.54-0.70). Shared environmental effects were not significant. The pairwise/probandwise concordance for idiopathic scoliosis in the Swedish Inpatient Register was 0.08/0.15 for monozygotic and zero/zero for same-sex dizygotic twins.

CONCLUSION

Using self-reported data on scoliosis from the Swedish Twin Registry, we estimate that 38% of the variance in the liability to develop scoliosis is due to additive genetic effects and 62% to unique environmental effects. This is the first study of sufficient size to make heritability estimates of scoliosis.

Pediatric scoliosis

Pediatric scoliosis is a relatively uncommon condition typically first noticed due to altered stature or by routine spine screenings by a school nurse or pediatrician. The formal diagnosis is made with spine radiographs, with coronal curvature measurement of 10° or greater. Treatment may consist of serial observation, bracing until skeletal maturity, or surgery for correction and fusion/stabilization of severe or progressive deformity. Overall success for non-operative management of scoliosis is affected by the etiology for the deformity, close follow up and monitoring for evolution of the deformity, and patient compliance with their treatment regimen. The most common surgical technique is a posterior approach spine fusion with implanted instrumentation, and patients are typically back to their activities of daily living by 6 months postoperatively. Continued intermittent monitoring of the scoliosis throughout adulthood is recommended, to detect late deformity progression, development of arthritis symptoms, or other associated issues.

Potential genetic markers predicting the outcome of brace treatment in patients with adolescent idiopathic scoliosis

PURPOSE

To investigate whether the predisposition genes previously reported to be associated with the occurrence or curve severity of adolescent idiopathic scoliosis (AIS) play a role in the effectiveness of brace treatment.

METHOD

A total of 312 AIS patients treated with bracing were enrolled in this study. The Cobb angle of the main curve was recorded at the beginning of brace treatment as well as at each follow-up. The patients were divided into two groups according to the outcome of brace treatment (success/failure). The failure of brace treatment was defined as a curve progression of more than 5° compared to the initial Cobb angle or surgical intervention because of curve progression. Single nucleotide polymorphism (SNP) sites in the genes for estrogen receptor α (ERα), estrogen receptor β (ERβ), tryptophan hydroxylase 1 (TPH-1), melatonin receptor 1B (MTNR1B) and matrillin-1 (MATN1), which were previously identified to be predisposition genes for AIS, were selected for genotyping by the PCR-RFLP method. Differences of genotype and allele distribution between the two groups were compared by the χ(2) test. A logistic regression analysis was used to figure out the independent predictors of the outcome of brace treatment.

RESULTS

There were 90 cases (28.8%) in the failure group and 222 cases (71.2%) in the success group. Patients in the failure group were associated with the genotype GA (50.9 vs. 17.9% p < 0.001) and the G allele (27.1 vs. 12.0%, p < 0.001) at SNP rs9340799 of the ERα gene. Similarly, they were also associated with the genotype AT (33.3 vs. 13.0%, p = 0.002) and the A allele (16.7 vs. 9.6%, p = 0.033) at SNP rs10488682 of the TPH-1 gene. For MTNR1B, the difference of genotype distribution between the two groups was found to be statistically significant, while the difference of allele distribution between the two groups was found to be marginally statistically significant; for the MATN1 and ERβ genes, we found no significant differences of the genotype or allele distribution between the two groups. In the logistic regression analysis, ERα and TPH-1 were demonstrated to be independent factors predictive of bracing effectiveness.

CONCLUSIONS

ERα and TPH-1 might be potential genetic markers that could predict the outcome of brace treatment. Patients with the G allele at the rs9340799 site of the ERα gene and the A allele at the rs10488682 site of the TPH-1 gene are prone to be resistant to brace treatment.

Management of degenerative disk disease and chronic low back pain

Degenerative disk disease is a strong etiologic risk factor of chronic low back pain (LBP). A multidisciplinary approach to treatment is often warranted. Patient education, medication, and cognitive behavioral therapies are essential in the treatment of chronic LBP sufferers. Surgical intervention with a rehabilitation regime is sometimes advocated. Prognostic factors related to the outcome of different treatments include maladaptive pain coping and genetics. The identification of pain genes may assist in determining individuals susceptible to pain and in patient selection for appropriate therapy. Biologic therapies show promise, but clinical trials are needed before advocating their use in humans.