Deletion of Pax1 scoliosis-associated regulatory elements leads to a female-biased tail abnormality.

Adolescent idiopathic scoliosis (AIS), a sideways curvature of the spine, is sexually dimorphic, with increased incidence in females. A genome-wide association study identified a female-specific AIS susceptibility locus near the PAX1 gene. Here, we use mouse enhancer assays, three mouse enhancer knockouts, and subsequent phenotypic analyses to characterize this region. Using mouse enhancer assays, we characterize a sequence, PEC7, which overlaps the AIS-associated variant, and find it to be active in the tail tip and intervertebral disc. Removal of PEC7 or Xe1, a known sclerotome enhancer nearby, or deletion of both sequences lead to a kinky tail phenotype only in the Xe1 and combined (Xe1+PEC7) knockouts, with only the latter showing a female sex dimorphic phenotype. Extensive phenotypic characterization of these mouse lines implicates several differentially expressed genes and estrogen signaling in the sex dimorphic bias. In summary, our work functionally characterizes an AIS-associated locus and dissects the mechanism for its sexual dimorphism.

A rare skeletal dysplasia in the etiology of severe scoliosis: Diaphanospondylodysostosis.

Diaphanospondylodysostosis is a rare genetic skeletal disorder caused by biallelic variants in the BMPER gene. The term, diaphanospondylodysostosis, includes ischiospinal dysotosis, which was previously known as a distinct entity with milder clinical features. The clinical phenotype of diaphanospondylodysostosis is quite variable with mortality in early postnatal life in some patients. Main clinical and radiographic features are narrow thorax, vertebral segmentation defects, rib anomalies, ossification defects of vertebrae, ischium and sacrum, and renal cysts. In this study, we report on a 14-year-old girl patient with diaphanospondylodysostosis harbouring a novel BMPER mutation. The patient presented with severe scoliosis and severely hypoplastic/aplastic distal phalanges of the fingers and toes, findings yet hitherto not described in this syndrome.

Deletion of a conserved genomic region associated with adolescent idiopathic scoliosis leads to vertebral rotation in mice.

Adolescent idiopathic scoliosis (AIS) is the most common form of scoliosis, in which spinal curvature develops in adolescence, and 90% of patients are female. Scoliosis is a debilitating disease that often requires bracing or surgery in severe cases. AIS affects 2%-5.2% of the population; however, the biological origin of the disease remains poorly understood. In this study, we aimed to determine the function of a highly conserved genomic region previously linked to AIS using a mouse model generated by CRISPR-CAS9 gene editing to knockout this area of the genome to understand better its contribution to AIS, which we named AIS_CRMΔ. We also investigated the upstream factors that regulate the activity of this enhancer in vivo, whether the spatial expression of the LBX1 protein would change with the loss of AIS-CRM function, and whether any phenotype would arise after deletion of this region. We found a significant increase in mRNA expression in the developing neural tube at E10.5, and E12.5, for not only Lbx1 but also other neighboring genes. Adult knockout mice showed vertebral rotation and proprioceptive deficits, also observed in human AIS patients. In conclusion, our study sheds light on the elusive biological origins of AIS, by targeting and investigating a highly conserved genomic region linked to AIS in humans. These findings provide valuable insights into the function of the investigated region and contribute to our understanding of the underlying causes of this debilitating disease.

Association of genetic variation in COL11A1 with adolescent idiopathic scoliosis.

Adolescent idiopathic scoliosis (AIS) is a common and progressive spinal deformity in children that exhibits striking sexual dimorphism, with girls at more than fivefold greater risk of severe disease compared to boys. Despite its medical impact, the molecular mechanisms that drive AIS are largely unknown. We previously defined a female-specific AIS genetic risk locus in an enhancer near the PAX1 gene. Here, we sought to define the roles of PAX1 and newly identified AIS-associated genes in the developmental mechanism of AIS. In a genetic study of 10,519 individuals with AIS and 93,238 unaffected controls, significant association was identified with a variant in COL11A1 encoding collagen (α1) XI (rs3753841; NM_080629.2_c.4004C>T; p.(Pro1335Leu); p=7.07E-11, OR = 1.118). Using CRISPR mutagenesis we generated Pax1 knockout mice (Pax1-/-). In postnatal spines we found that PAX1 and collagen (α1) XI protein both localize within the intervertebral disc-vertebral junction region encompassing the growth plate, with less collagen (α1) XI detected in Pax1-/- spines compared to wild-type. By genetic targeting we found that wild-type Col11a1 expression in costal chondrocytes suppresses expression of Pax1 and of Mmp3, encoding the matrix metalloproteinase 3 enzyme implicated in matrix remodeling. However, the latter suppression was abrogated in the presence of the AIS-associated COL11A1P1335L mutant. Further, we found that either knockdown of the estrogen receptor gene Esr2 or tamoxifen treatment significantly altered Col11a1 and Mmp3 expression in chondrocytes. We propose a new molecular model of AIS pathogenesis wherein genetic variation and estrogen signaling increase disease susceptibility by altering a PAX1-COL11a1-MMP3 signaling axis in spinal chondrocytes.

Adolescent idiopathic scoliosis (AIS) is a twisting deformity of the spine that occurs during periods of rapid growth in children worldwide. Children with severe cases of AIS require surgery to stop it from getting worse, presenting a significant financial burden to health systems and families. Although AIS is known to cluster in families, its genetic causes and its inheritance pattern have remained elusive. Additionally, AIS is known to be more prevalent in females, a bias that has not been explained. Advances in techniques to study the genetics underlying diseases have revealed that certain variations that increase the risk of AIS affect cartilage and connective tissue. In humans, one such variation is near a gene called Pax1, and it is female-specific. The extracellular matrix is a network of proteins and other molecules in the space between cells that help connect tissues together, and it is particularly important in cartilage and other connective tissues. One of the main components of the extracellular matrix is collagen. Yu, Kanshour, Ushiki et al. hypothesized that changes in the extracellular matrix could affect the cartilage and connective tissues of the spine, leading to AIS. To show this, the scientists screened over 100,000 individuals and found that AIS is associated with variants in two genes coding for extracellular matrix proteins. One of these variants was found in a gene called Col11a1, which codes for one of the proteins that makes up collagen. To understand the relationship between Pax1 and Col11a1, Yu, Kanshour, Ushiki et al. genetically modified mice so that they would lack the Pax1 gene. In these mice, the activation of Col11a1 was reduced in the mouse spine. They also found that the form of Col11a1 associated with AIS could not suppress the activation of a gene called Mmp3 in mouse cartilage cells as effectively as unmutated Col11a1. Going one step further, the researchers found that lowering the levels of an estrogen receptor altered the activation patterns of Pax1, Col11a1, and Mmp3 in mouse cartilage cells. These findings suggest a possible mechanism for AIS, particularly in females. The findings of Yu, Kanshour, Ushiki et al. highlight that cartilage cells in the spine are particularly relevant in AIS. The results also point to specific molecules within the extracellular matrix as important for maintaining proper alignment in the spine when children are growing rapidly. This information may guide future therapies aimed at maintaining healthy spinal cells in adolescent children, particularly girls.

Horizontal gaze palsy with progressive scoliosis.

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare autosomal recessive condition characterized by absence of abduction and adduction movements with intact vertical eye movements and progressive scoliosis. Patients usually present by mid-childhood with complaints of progressive scoliosis. The clinical diagnosis of HGPPS can be further confirmed by the ROBO3 gene mutation on chromosome number 11. We present 2 Indian siblings who were incidentally diagnosed with HGPPS with synergistic convergence on regular eye examination; diagnosis was confirmed by radiological and genetic testing.

Investigating the Differential Circulating microRNA Expression in Adolescent Females with Severe Idiopathic Scoliosis: A Proof-of-Concept Observational Clinical Study.

Adolescent Idiopathic Scoliosis (AIS) is the most common form of three-dimensional spinal disorder in adolescents between the ages of 10 and 18 years of age, most commonly diagnosed in young women when severe disease occurs. Patients with AIS are characterized by abnormal skeletal growth and reduced bone mineral density. The etiology of AIS is thought to be multifactorial, involving both environmental and genetic factors, but to date, it is still unknown. Therefore, it is crucial to further investigate the molecular pathogenesis of AIS and to identify biomarkers useful for predicting curve progression. In this perspective, the relative abundance of a panel of microRNAs (miRNAs) was analyzed in the plasma of 20 AIS patients and 10 healthy controls (HC). The data revealed a significant group of circulating miRNAs dysregulated in AIS patients compared to HC. Further bioinformatic analyses evidenced a more restricted expression of some miRNAs exclusively in severe AIS females. These include some members of the miR-30 family, which are considered promising regulators for treating bone diseases. We demonstrated circulating extracellular vesicles (EVs) from severe AIS females contained miR-30 family members and decreased the osteogenic differentiation of mesenchymal stem cells. Proteomic analysis of EVs highlighted the expression of proteins associated with orthopedic disease. This study provides preliminary evidence of a miRNAs signature potentially associated with severe female AIS and suggests the corresponding vesicular component may affect cellular mechanisms crucial in AIS, opening the scenario for in-depth studies on prognostic differences related to gender and grade.

SOX9 gene shows association with adolescent idiopathic scoliosis predisposition in Northwest Indians.

BACKGROUND: Adolescent idiopathic scoliosis (AIS) is a common structural deformity of the spine affecting adolescent individuals globally. The disorder is polygenic and is accompanied by the association of various genetic loci. Genetic studies in Chinese and Japanese populations have shown the association of genetic variants of SOX9 with AIS curve severity. However, no genetic study evaluating the association of SRY-Box Transcription Factor 9 (SOX9) variants with AIS predisposition has been conducted in any Indian population. Thus, we aimed to investigate the association of the genetic variants of the SOX9 along with 0.88 Mb upstream region with AIS susceptibility in the population of Northwest India. METHODS: In total, 113 AIS cases and 500 non-AIS controls were recruited from the population of Northwest India in the study and screened for 155 genetic variants across the SOX9 gene and 0.88 Mb upstream region of the gene using Global Screening Array-24 v3.0 chip (Illumina). The statistical significance of the Bonferroni threshold was set at 0.000322. RESULT: The results showed the association of 11 newly identified variants; rs9302936, rs7210997, rs77736349, rs12940821, rs9302937, rs77447012, rs8071904, rs74898711, rs9900249, rs2430514, and rs1042667 with the AIS susceptibility in the studied population. Only one variant, rs2430514, was inversely associated with AIS in the population, while the ten variants were associated with the AIS risk. Moreover, 47 variants clustered in the gene desert region of the SOX9 gene were associated at a p-value ≤ 0.05. CONCLUSION: The present study is the first to demonstrate the association of SOX9 enhancer locus variants with AIS in any South Asian Indian population. The results are interesting as rs1042667, a 3' untranslated region (UTR) variant in the exon 3 and upstream variants of the SOX9 gene, were associated with AIS susceptibility in the Northwest Indian population. This provides evidence that the variants in the enhancer region of SOX9 might regulate its gene expression, thus leading to AIS pathology and might act as an important gene for AIS susceptibility.

A Study of Polish Family with Scoliosis and Limb Contractures Expands the MYH3 Disease Spectrum.

A disease associated with malfunction of the MYH3 gene is characterised by scoliosis, contractures of the V fingers, knees and elbows, dysplasia of the calf muscles, foot deformity and limb length asymmetry. The aim of this study was to identify the cause of musculoskeletal deformities in a three-generation Polish family by exome sequencing. The segregation of the newly described c.866A>C variant of the MYH3 gene in the family indicates an autosomal dominant model of inheritance. The detected MYH3 variant segregates the disease within the family. The presented results expand the MYH3 disease spectrum and emphasize the clinical diagnostic challenge in syndromes harbouring congenital spine defects and joint contractures.

Impaired glycine neurotransmission causes adolescent idiopathic scoliosis.

Adolescent idiopathic scoliosis (AIS) is the most common form of spinal deformity, affecting millions of adolescents worldwide, but it lacks a defined theory of etiopathogenesis. Because of this, treatment of AIS is limited to bracing and/or invasive surgery after onset. Preonset diagnosis or preventive treatment remains unavailable. Here, we performed a genetic analysis of a large multicenter AIS cohort and identified disease-causing and predisposing variants of SLC6A9 in multigeneration families, trios, and sporadic patients. Variants of SLC6A9, which encodes glycine transporter 1 (GLYT1), reduced glycine-uptake activity in cells, leading to increased extracellular glycine levels and aberrant glycinergic neurotransmission. Slc6a9 mutant zebrafish exhibited discoordination of spinal neural activities and pronounced lateral spinal curvature, a phenotype resembling human patients. The penetrance and severity of curvature were sensitive to the dosage of functional glyt1. Administration of a glycine receptor antagonist or a clinically used glycine neutralizer (sodium benzoate) partially rescued the phenotype. Our results indicate a neuropathic origin for "idiopathic" scoliosis, involving the dysfunction of synaptic neurotransmission and central pattern generators (CPGs), potentially a common cause of AIS. Our work further suggests avenues for early diagnosis and intervention of AIS in preadolescents.

CATSHL syndrome, a new family and phenotypic expansion.

We report the case of a 12-year-old girl and her father who both had marked postnatal tall stature, camptodactyly and clinodactyly, scoliosis and juvenile-onset hearing loss. The CATSHL (CAmptodactyly - Tall stature - Scoliosis - Hearing Loss syndrome) syndrome was suspected, and molecular analysis revealed a hitherto unreported, monoallelic variant c.1861C>T (p.Arg621Cys) in FGFR3. This variant affects the same residue, but is different than, the variant p.Arg621His reported in the two families with dominant CATSHL described so far. Interestingly, peg-shaped incisors were observed in the proband, a feature never reported in CATSHL but typical of another FGFR3-related condition, LADD (Lacrimo - Auricolo - Dento - Digital) syndrome. The FGFR3 p.Arg621Cys variant seems to be a newly identified cause of CATSHL syndrome with some phenotypic overlap with the LADD syndrome.

Association between genetic polymorphisms and risk of adolescent idiopathic scoliosis in case-control studies: a systematic review.

BACKGROUND: Adolescent idiopathic scoliosis (AIS) is a structural lateral spinal curvature of ≥10° with rotation. Approximately 2%-3% of children across populations are affected with AIS, and this condition is responsible for ~$3 billion in costs within the USA. Although AIS is believed to have a strong genetic contribution, clinical translation of identified genetic variants has stalled. METHODS: The databases MEDLINE (via PubMed), Embase, Google Scholar and Ovid MEDLINE were searched and limited to articles in English. Title and abstract, full-text and data extraction screening was conducted through Covidence, followed by data transfer to a custom REDCap database. Studies containing variant-level data using genome-wide methodology as well as validation studies of genome-wide methods were considered. Quality assessment was conducted using Q-Genie. RESULTS: 33 studies were included, including 9 genome-wide association studies, 4 whole exome sequencing and 20 validation studies. Combined, these studies included data from >35,000 cases and >67,000 controls, not including validation cohorts. Additionally, results from six meta-analyses containing novel cohorts were also reported. All included study cohorts were from populations of primarily East Asian or Caucasian descent. Quality assessment found that overall study quality was high and control group selection was moderate. The highest number of reported associations were in single nucleotide polymorphisms (SNPs) in or near LBX1, LBX1-AS1, GPR126/ADGRG6 or BNC2. CONCLUSION: AIS risk may be influenced by specific SNPs, particularly those in/near LBX1 and GPR126. Translatability of study findings is unknown due to an underrepresentation of most ethnic groups as well as few identified genome-wide studies. Further studies may benefit from increased cohort diversity and thorough evaluation of control cohort groups.

Association of polymorphism in leptin receptor gene with susceptibility of adolescent idiopathic scoliosis.

PURPOSE: Abnormal leptin bioavailability has play key roles in the etiology of adolescent idiopathic scoliosis (AIS). Both leptin and its receptor levels may be modulated by the presence of genetic polymorphisms. This study aimed to evaluate the role of polymorphisms in the leptin (LEP) and its main receptor (LEPR) genes in the AIS susceptibility in girls. METHODS: A retrospective case-control study was conducted with 189 AIS and 240 controls. LEP rs2167270 and LEPR rs2767485 polymorphisms were genotyped using a TaqMan validated assay. Associations were evaluated by odds ratios (OR) and 95% confidence intervals (CI). RESULTS: The AIS group showed a predominance of girls under 18 years old (n = 140, 74.1%), 148 (78.3%) had low or normal BMI, 111 (58.7%) had Cobb ≥ 45º and 130 (68.7%) were skeletally mature. Minor allele frequencies of rs2167270 and rs2767485 were 35.7% and 18.3%, for AIS and 35.6% and 25.4% for controls, respectively. LEPR rs2767485 T and TC + TT were associated with higher risk of AIS (OR = 1.53; 95% CI = 1.09-2.13 and OR = 1.84; 95% CI = 1.69-2.01, respectively), since CC genotype was only present in the control group. In addition, the LEP rs2167270 GA + AA was more frequent in low weight group (BMI ≤ 24.9) of girls with AIS. There was no significant association between LEP rs2167270 and AIS susceptibility, and LEPR rs2767485 and BMI. CONCLUSION: The LEPR rs2767485 was associated with the genetic susceptibility of AIS and LEP rs2167270 with low BMI. These data can contribute to the identification of genetic biomarkers to improve the diagnosis and treatment.

Asymmetric expression of PIEZO2 in paraspinal muscles of adolescent idiopathic scoliosis.

BACKGROUND: Muscle imbalance has long been recognized as one of the possible pathogeneses for adolescent idiopathic scoliosis (AIS). PIEZO2, the susceptibility gene of AIS, has been identified to play an important role in neuromuscular activities. OBJECTIVE: This study aims to compare the mRNA expression of PIEZO2 between concave and convex paraspinal muscles of AIS patients and to identify the relationship between the ratio of PIEZO2 expression and curve magnitude. METHODS: Twenty female AIS patients (right thoracic curve) who underwent spinal correction surgery were divided into moderate (n= 12) and severe (⩾ 70 degrees) curve groups (n= 8). The morphology of the paraspinal muscles was assessed with spinal MRI. Multifidus specimens were collected during surgical operations from the concave and convex sides of the apical region, and mRNA expression of the PIEZO2 gene was compared between sides. The localization of PIEZO2 protein expression was confirmed with the markers PAX7 and PAX3, and the percentage of PIEZO2+ cells was also investigated. RESULTS: In the moderate curve group, fatty infiltration in the deep paraspinal muscle was significantly higher on the concave side than on the convex side. There were no differences in deep muscle area, superficial muscle area, or fatty infiltration of superficial paraspinal muscle. The mRNA expression of PIEZO2 was significantly increased on the concave side, and the asymmetric expression predominantly occurred in moderate curves rather than severe ones. PIEZO2 was expressed on satellite cells instead of fibers of the muscle spindle. The percent of PIEZO2+PAX7+ cells in myofibers was significantly higher on the concave side in the moderate curve group, but not in the severe curve group. CONCLUSIONS: Asymmetric morphological changes occur in the deep paraspinal muscles of AIS. The PIEZO2 is asymmetrically expressed in the multifidus muscle and is preferentially expressed in satellite cells.

Identification of key genes and regulatory mechanisms in adult degenerative scoliosis.

BACKGROUND: Adult degenerative scoliosis (ADS) is a spinal disorder, but its pathogenesis remain unclear. Therefore, in this study, we utilized data from the GEO database and explored the key genes and regulatory mechanisms involved in ADS. METHODS: We performed bioinformatics analysis on the GSE209825 dataset of GEO database. Weighted gene co-expression network analysis (WGCNA) was used to identify ADS-related gene modules, and we performed gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. We constructed a protein-protein interaction (PPI) network using the STRING database. We validated the specificity of hub genes in ADS using the GSE34095 dataset and plotted ROC curves for the identification of different degenerative spinal diseases based on the hub genes expression RESULTS: We identified 113 differentially expressed lncRNAs. WGCNA identified the MEblack module had the strongest correlation to ADS. GO and KEGG analyses of target genes in lncRNAs revealed their involvement in immune responses, inflammation, cellular processes, and metabolic pathways. Through PPI and ROC analysis, 10 hub genes linked to ADS diseases with certain specificity were found: ELANE, LTF, DEFA1B, SLC2A4, DEFA1, FAXDC2, LCN2, CTSB, FDFT1, and AURKA. CONCLUSIONS: We identified 10 potential hub genes associated with ADS and constructed a transcription factors (TFs)-lncRNAs-hub genes regulatory network. These findings provide a new direction and research basis for the targeted treatment and mechanism research of ADS.

Identification of novel homozygous nonsense SLC10A7 variant causing short stature, amelogenesis imperfecta, and skeletal dysplasia with scoliosis and surgical management of spine.

BACKGROUND: Short stature, amelogenesis imperfecta, and skeletal dysplasia with scoliosis is a rare, autosomal recessive, skeletal disorder first described in 2018. This syndrome starts with pre- and postnatal developmental delay, and gradually presents with variable facial dysmorphisms, a short stature, amelogenesis imperfecta, and progressive skeletal dysplasia affecting the limbs, joints, hands, feet, and spine. CASE PRESENTATION: We identified a homozygous novel nonsense mutation in exon 1 of SLC10A7 (NM_001300842.2: c.100G > T / p.Gly34*) segregating with the typical disease phenotype in a Han Chinese family. We reviewed the 12-year surgical treatment history with seven interventions on spine. CONCLUSION: To date, only 12 cases of the SLC10A7 mutation have been reported, mainly from consanguineous families. Our patient showed a relatively severe and broad clinical phenotype compared with previously reported cases. In this patient, annual check-ups and timely surgeries led to a good outcome.

A novel intronic variant in ROBO3 associated with horizontal gaze palsy with progressive scoliosis: case report and literature review.

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare, autosomal recessive inherited disorder caused by mutations in ROBO3 gene. The clinical features of HGPPS include horizontal gaze palsy, progressive scoliosis, other oculomotor abnormalities such as strabismus and nystagmus. Whole-exome sequencing (WES) is used to diagnose rare Mendelian disorders, when routine standard tests have failed to make a formal pathological diagnosis. However, WES may identify variants of uncertain significance (VUS) that may add further ambiguity to the diagnosis. We report the case of a 4-year-old boy with horizontal gaze palsy, progressive scoliosis, microcephaly, and mild developmental delay. WES identified an intronic VUS in ROBO3 gene. We performed minigene splicing functional analysis to confirm the pathogenicity of this VUS. This report illustrates that WES data analysis with supportive functional analysis provides an effective approach to improve the diagnostic yield for unsolved clinical cases. This case also highlights the phenotypic heterogeneity in patients with HGPPS.

A Stop-gain Variant c.220C>T (p.(Gln74*)) in FLNB Segregates with Spondylocarpotarsal Synostosis Syndrome in a Consanguineous Family.

Spondylocarpotarsal synostosis (SCT) syndrome is a very rare and severe form of skeletal dysplasia. The hallmark features of SCT are disproportionate short stature, scoliosis, fusion of carpal and tarsal bones, and clubfoot. Other common manifestations are cleft palate, conductive and sensorineural hearing loss, joint stiffness, and dental enamel hypoplasia. Homozygous variants in FLNB are known to cause SCT. This study was aimed to investigate the phenotypic and genetic basis of unique presentation of SCT syndrome segregating in a consanguineous Pakistani family. Three of the four affected siblings evaluated had severe short stature, short trunk, short neck, kyphoscoliosis, pectus carinatum, and winged scapula. The subjects had difficulty in walking and gait problems and complained of knee pain and backache. Roentgenographic examination of the eldest patient revealed gross anomalies in the axial skeleton including thoracolumbar and cervical fusion of ribs, severe kyphoscoliosis, thoracic and lumbar lordosis, coxa valga, fusion of certain carpals and tarsals, and clinodactyly. The patients had normal faces and lacked other typical features of SCT like cleft palate, conductive and sensorineural hearing loss, joint stiffness, and dental enamel hypoplasia. Whole exome sequencing (WES) of two affected siblings led to the discovery of a rare stop-gain variant c.220C>T (p.(Gln74*)) in exon 1 of the FLNB gene. The variant was homozygous and segregated with the malformation in this family. This study reports extensive phenotypic variability in SCT and expands the mutation spectrum of FLNB.

BMP6 participates in the pathogenesis of adolescent idiopathic scoliosis by regulating osteopenia.

Adolescent idiopathic scoliosis (AIS) is a complex disease characterized by three-dimensional structural deformities of the spine. Its pathogenesis is associated with osteopenia. Bone-marrow-derived mesenchymal stem cells (BMSCs) play an important role in bone metabolism. We detected 1919 differentially expressed mRNAs and 744 differentially expressed lncRNAs in BMSCs from seven patients with AIS and five patients without AIS via high-throughput sequencing. Multiple analyses identified bone morphogenetic protein-6 (BMP6) as a hub gene that regulates the abnormal osteogenic differentiation of BMSCs in AIS. BMP6 expression was found to be decreased in AIS and its knockdown in human BMSCs significantly altered the degree of osteogenic differentiation. Additionally, CAP1-217 has been shown to be a potential upstream regulatory molecule of BMP6. We showed that CAP1-217 knockdown downregulated the expression of BMP6 and the osteogenic differentiation of BMSCs. Simultaneously, knockout of BMP6 in zebrafish embryos significantly increased the deformity rate. The findings of this study suggest that BMP6 is a key gene that regulates the abnormal osteogenic differentiation of BMSCs in AIS via the CAP1-217/BMP6/RUNX2 axis.

Scoliosis in osteogenesis imperfecta: identifying the genetic and non-genetic factors affecting severity and progression from longitudinal data of 290 patients.

BACKGROUND: Scoliosis is widely prevalent among osteogenesis imperfecta (OI) patients, and is progressive with age. However, factors affecting scoliosis in OI are not well known. METHODS: We retrospectively retrieved longitudinal radiographic and clinical records of consecutive OI patients seeking treatments at our hospital from 2014 to 2022, graded their pre-operative spinal conditions into four outcome groups, estimated their progression rates, and descriptively and inferentially analyzed the genetic and non-genetic factors that may affect the outcomes and progression rates. RESULTS: In all, 290 OI patients met the inclusion criteria, where 221 had genetic records. Of these 221, about 2/3 had mutations in COL1A1 or COL1A2, followed by mutations in WNT1 (9.0%), IFITM5 (9.0%) and other OI risk genes. With an average age of 12.0 years (interquartile range [IQR] 6.9-16.1), 70.7% of the cohort had scoliosis (Cobb angle > 10°), including 106 (36.5%) mild (10°-25°), 40 (13.8%) moderate (25°-50°), and 59 (20.3%) severe (> 50°) scoliosis patients. Patients with either COL1A1 and COL1A2 were strongly biased toward having mild or no scoliosis, whereas patients with mutations in IFITM5, WNT1 and other recessive genes were more evenly distributed among the four outcome grades. Lower-limb discrepancy, bone mineral density (BMD) and age of first drug used were all significantly correlated with severity outcomes. Using multivariate logistic regression, we estimated that each year older adds an odds ratio of 1.13 (95% confidence interval [CI] 1.07-1.2) in progression into advanced stages of scoliosis. We estimated a cohort-wide progression rate of 2.7 degrees per year (95% CI 2.4-3.0). Early-onset patients experienced fast progressions during both infantile and adolescent stages. Twenty-five of the 59 (42.8%) patients with severe scoliosis underwent spinal surgeries, enjoying an average Cobb angle reduction of 33° (IQR 23-40) postoperatively. CONCLUSION: The severity and progression of scoliosis in osteogenesis imperfecta were affected by genetic factors including genotypes and mutation types, and non-genetic factors including age and BMD. As compared with COL1A1, mutations in COL1A2 were less damaging while those on IFITM5 and other recessive genes conferred damaging effects. Progression rates were the fastest in the adolescent adult age-group.

Differential Gene Expression Profiles and Pathways Highlight the Role of Osteoimmunology in Neurofibromatosis Type 1-Related Dystrophic Scoliosis With Osteopenia.

STUDY DESIGN: Microarray approach and integrated gene network analysis. OBJECTIVE: To explore the differential genetic expression profile, Gene Ontology terms, and Kyoto Encyclopedia of Genes and Genomes pathways in human trabecular bone (HTB)-derived cells of dystrophic scoliosis secondary to neurofibromatosis type 1 (DS-NF1) and compare these to normal controls. SUMMARY OF BACKGROUND DATA: The pathogenesis of DS-NF1 and the accompanying generalized osteopenia remain unclear. We hypothesized that HTBs may play a significant role in the etiology and pathogenesis of DS-NF1. MATERIALS AND METHODS: Microarray analysis was used to identify differentially expressed genes of HTBs from patients with DS-NF1 compared with those from healthy individuals. Functional and pathway enrichment analysis were implemented through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway database. Then, the "search tool for the retrieval of interacting genes/proteins" database, Cytoscape, and "Molecular Complex Detection" were applied to construct the protein-protein interaction (PPI) network and screen hub genes. Pathway enrichment analysis was further performed for hub genes and gene clusters identified through module analysis. Six potential crucial genes were selected for validation by reverse transcription polymerase chain reaction. RESULTS: Bioinformatic analysis revealed that there are 401 previously unrecognized differentially expressed genes (238 up and 163 downregulated genes) in HTBs from patients with DS-NF1, and they were mainly enriched in terms of immune response, type-I interferon (IFN) signaling, TNF signaling pathway and etinoic acid inducible gene I-like receptor signaling pathway. Five hub genes, including signal transducer and activator of transcription 1, 2'-5'-oligoadenylate synthetase-like, IFN induced with helicase C domain 1, IFN regulatory factor 7, and MX dynamin-like GTPase 1 were identified through PPI network, which were mainly enriched in terms of Jak-STAT and etinoic acid inducible gene I-like receptor signaling pathway. An independently dysregulated protein cluster containing CCL2, CXCL1, CXCL3, CX3CL1, TLR1 , and CXCL12 was also identified through the PPI network. This indicated that the upper abnormally expressed genes may play essential roles in DS-NF1 pathogenesis and accompanied osteopenia. CONCLUSION: Six key genes were identified in the progression of DS-NF1-related osteopenia. Immune response might play a key role in the progression of osteopenia, whereas a CXCL12 -mediated osteogenic effect might play a protective role.