Sequencing of the TBX6 Gene in Families with Familial Idiopathic Scoliosis

Differential Regulation of POC5 by ERα in Human Normal and Scoliotic Cells

Adolescent idiopathic scoliosis (AIS) is a complex three-dimensional spinal deformity. The incidence of AIS in females is 8.4 times higher than in males. Several hypotheses on the role of estrogen have been postulated for the progression of AIS. Recently, Centriolar protein gene POC5 (POC5) was identified as a causative gene of AIS. POC5 is a centriolar protein that is important for cell cycle progression and centriole elongation. However, the hormonal regulation of POC5 remains to be determined. Here, we identify POC5 as an estrogen-responsive gene under the regulation of estrogen receptor ERα in normal osteoblasts (NOBs) and other ERα-positive cells. Using promoter activity, gene, and protein expression assays, we found that the POC5 gene was upregulated by the treatment of osteoblasts with estradiol (E2) through direct genomic signaling. We observed different effects of E2 in NOBs and mutant POC5^A429V AIS osteoblasts. Using promoter assays, we identified an estrogen response element (ERE) in the proximal promoter of POC5, which conferred estrogen responsiveness through ERα. The recruitment of ERα to the ERE of the POC5 promoter was also potentiated by estrogen. Collectively, these findings suggest that estrogen is an etiological factor in scoliosis through the deregulation of POC5.

Case Report: DNAAF4 Variants Cause Primary Ciliary Dyskinesia and Infertility in Two Han Chinese Families

Background: Primary ciliary dyskinesia (PCD) is a rare genetic disorder, predominantly autosomal recessive. The dynein axonemal assembly factor 4 (DNAAF4) is mainly involved in the preassembly of multisubunit dynein protein, which is fundamental to the proper functioning of cilia and flagella. There are few reports of PCD-related pathogenic variants of DNAAF4, and almost no DNAAF4-related articles focused on sperm phenotype. Moreover, the association between DNAAF4 and scoliosis has never been reported, to the best of our knowledge.

Materials and Methods: We recruited two patients with a clinical diagnosis of PCD. One came from a consanguineous and another from a non-consanguineous family. Clinical data, laboratory test results, and imaging data were analyzed. Through whole exome sequencing, immunofluorescence, electron microscopy, high-speed video microscopy analysis, and hematoxylin–eosin (HE) staining, we identified the disease-associated variants and validated the pathogenicity.

Results: Proband 1 (P1, F1: II-1), a 19-year-old man, comes from a non-consanguineous family-I, and proband 2 (P2, F2: II-1), a 37-year-old woman, comes from a consanguineous family-II. Both had sinusitis, bronchiectasis, situs inversus, and scoliosis. P1 also had asthenoteratozoospermia, and P2 had an immature uterus. Two homozygous pathogenic variants in DNAAF4 (NM_130810.4), c.988C > T, p.(Arg330Trp), and DNAAF4 (NM_130810.4), c.733 C > T, p.(Arg245*), were identified through whole exome sequencing. High-speed microscopy analysis showed that most of the cilia were static in P1, with complete static of the respiratory cilia in P2. Immunofluorescence showed that the outer dynein arms (ODA) and inner dynein arms (IDA) were absent in the respiratory cilia of both probands, as well as in the sperm flagellum of P1. Transmission electron microscopy revealed the absence of ODA and IDA of respiratory cilia of P2, and HE staining showed irregular, short, absent, coiled, and bent flagella.

Conclusion: Our study identified a novel variant c.733C > T, which expanded the spectrum of DNAAF4 variants. Furthermore, we linked DNAAF4 to asthenoteratozoospermia and likely scoliosis in patients with PCD. This study will contribute to a better understanding of PCD.

Role of Primary Cilia in Skeletal Disorders

Primary cilia are highly conserved microtubule-based organelles that project from the cell surface into the extracellular environment and play important roles in mechanosensation, mechanotransduction, polarity maintenance, and cell behaviors during organ development and pathological changes. Intraflagellar transport (IFT) proteins are essential for cilium formation and function. The skeletal system consists of bones and connective tissue, including cartilage, tendons, and ligaments, providing support, stability, and movement to the body. Great progress has been achieved in primary cilia and skeletal disorders in recent decades. Increasing evidence suggests that cells with cilium defects in the skeletal system can cause numerous human diseases. Moreover, specific deletion of ciliary proteins in skeletal tissues with different Cre mice resulted in diverse malformations, suggesting that primary cilia are involved in the development of skeletal diseases. In addition, the intact of primary cilium is essential to osteogenic/chondrogenic induction of mesenchymal stem cells, regarded as a promising target for clinical intervention for skeletal disorders. In this review, we summarized the role of primary cilia and ciliary proteins in the pathogenesis of skeletal diseases, including osteoporosis, bone/cartilage tumor, osteoarthritis, intervertebral disc degeneration, spine scoliosis, and other cilium-related skeletal diseases, and highlighted their promising treatment methods, including using mesenchymal stem cells. Our review tries to present evidence for primary cilium as a promising target for clinical intervention for skeletal diseases.

Towards clinical applications of in vitro-derived axial progenitors

The production of the tissues that make up the mammalian embryonic trunk takes place in a head-tail direction, via the differentiation of posteriorly-located axial progenitor populations. These include bipotent neuromesodermal progenitors (NMPs), which generate both spinal cord neurectoderm and presomitic mesoderm, the precursor of the musculoskeleton. Over the past few years, a number of studies have described the derivation of NMP-like cells from mouse and human pluripotent stem cells (PSCs). In turn, these have greatly facilitated the establishment of PSC differentiation protocols aiming to give rise efficiently to posterior mesodermal and neural cell types, which have been particularly challenging to produce using previous approaches. Moreover, the advent of 3-dimensional-based culture systems incorporating distinct axial progenitor-derived cell lineages has opened new avenues toward the functional dissection of early patterning events and cell vs non-cell autonomous effects. Here, we provide a brief overview of the applications of these cell types in disease modelling and cell therapy and speculate on their potential uses in the future.

Exploring the association between specific genes and the onset of idiopathic scoliosis: a systematic review

Background

Idiopathic Scoliosis (IS) is the most common spinal deformity in adolescents, accounting for 80% of all spinal deformities. However, the etiology remains uncertain in most cases, being identified as Adolescent Idiopathic Scoliosis (AIS). IS treatments range from observation and sport to bracing or surgery. Several risk factors including sex and familiarity, have been linked with IS. Although there are still many uncertainties regarding the cause of this pathology, several studies report a greater incidence of the defect in families in which at least one other first degree relative is affected. This study systematically reviews the available literature to identify the most significant genes or variants related to the development and onset of IS.

Methods

The research question was formulated using a PIOS approach on the following databases: Medline, Embase, Cinahl, Scopus, Web of Science and Google Scholar. The search was performed from July to August 2021, and articles from the inception of the database to August 2021 were searched.

Results

24 of the 919 initially identified studies were included in the present review. The 24 included studies observed a total of 16,316 cases and 81,567 controls. All the considered studies stated either the affected gene and/or specific SNPs. CHD7, SH2B1, ESR, CALM1, LBX1, MATN1, CHL1, FBN1 and FBN2 genes were associated with IS development.

Conclusions

Although association can be found in some candidate genes the field of research regarding genetic association with the onset of IS still requires more information.

Identification of Two Novel DNAAF2 Variants in Two Consanguineous Families with Primary Ciliary Dyskinesia

Background

Dynein axonemal assembly factor 2 (DNAAF2) is involved in the early preassembly of dynein in the cytoplasm, which is essential for motile cilia function. Primary ciliary dyskinesia (PCD) associated with DNAAF2 variants has rarely been reported in females with infertility. Moreover, there is no report linking DNAAF2 to scoliosis in human.

Materials and Methods

We recruited patients from two consanguineous families with a clinical diagnosis of PCD and collected their clinical history, laboratory tests, and radiographic data. Sequencing and bioinformatics analysis were then performed. Immunofluorescence and high-speed microscope analysis were used to support the pathogenicity of the variant.

Results

Proband 1, a 26-year-old female from family I, exhibited scoliosis, bronchiectasis, sinusitis, situs inversus, and infertility. We found a novel homozygous missense variant in DNAAF2, c.491T>C, p.(Leu164Pro) in this patient. Subsequent immunofluorescence indicated the absence of outer dynein arm and inner dynein arm of cilia, and high-speed microscopy analysis showed that the most of the cilia are static, which support the pathogenicity of this variant. Proband 2, a 53-year-old female, presented with bronchiectasis, sinusitis, and infertility. In this patient, a new homozygous frameshift variant DNAAF2, c.822del, p.(Ala275Profs*10) was identified. The disease-causing variants mentioned above are not included in the current authorized genetic databases.

Conclusion

Our findings expand the spectrum of DNAAF2 variants and link DNAAF2 to female infertility and likely scoliosis in patients with PCD.

Genetic variant of TTLL11 gene and subsequent ciliary defects are associated with idiopathic scoliosis in a 5-generation UK family

Idiopathic scoliosis (IS) is a complex 3D deformation of the spine with a strong genetic component, most commonly found in adolescent girls. Adolescent idiopathic scoliosis (AIS) affects around 3% of the general population. In a 5-generation UK family, linkage analysis identified the locus 9q31.2-q34.2 as a candidate region for AIS; however, the causative gene remained unidentified. Here, using exome sequencing we identified a rare insertion c.1569_1570insTT in the tubulin tyrosine ligase like gene, member 11 (TTLL11) within that locus, as the IS causative gene in this British family. Two other TTLL11 mutations were also identified in two additional AIS cases in the same cohort. Analyses of primary cells of individuals carrying the c.1569_1570insTT (NM_194252) mutation reveal a defect at the primary cilia level, which is less present, smaller and less polyglutamylated compared to control. Further, in a zebrafish, the knock down of ttll11, and the mutated ttll11 confirmed its role in spine development and ciliary function in the fish retina. These findings provide evidence that mutations in TTLL11, a ciliary gene, contribute to the pathogenesis of IS.

Clinical Observations and Treatment Approaches for Scoliosis in Prader-Willi Syndrome

Prader–Willi syndrome (PWS) is recognized as the first example of genomic imprinting, generally due to a de novo paternal 15q11-q13 deletion. PWS is considered the most common genetic cause of marked obesity in humans. Scoliosis, kyphosis, and kyphoscoliosis are commonly seen in children and adolescents with PWS with a prevalence of spinal deformities cited between 15% to 86%. Childhood risk is 70% or higher, until skeletal maturity, with a bimodal age distribution with one peak before 4 years of age and the other nearing adolescence. As few reports are available on treating scoliosis in PWS, we described clinical observations, risk factors, therapeutic approaches and opinions regarding orthopedic care based on 20 years of clinical experience. Treatments include diligent radiographic screening, starting once a child can sit independently, ongoing physical therapy, and options for spine casting, bracing and surgery, depending on the size of the curve, and the child’s age. Similarly, there are different surgical choices including a spinal fusion at or near skeletal maturity, versus a construct that allows continued growth while controlling the curve for younger patients. A clear understanding of the risks involved in surgically treating children with PWS is important and will be discussed.

Distal chromosome 16p11.2 duplications containing SH2B1 in patients with scoliosis

INTRODUCTION

Adolescent idiopathic scoliosis (AIS) is a common musculoskeletal disorder with strong evidence for a genetic contribution. CNVs play an important role in congenital scoliosis, but their role in idiopathic scoliosis has been largely unexplored.

METHODS

Exome sequence data from 1197 AIS cases and 1664 in-house controls was analysed using coverage data to identify rare CNVs. CNV calls were filtered to include only highly confident CNVs with >10 average reads per region and mean log-ratio of coverage consistent with single-copy duplication or deletion. The frequency of 55 common recurrent CNVs was determined and correlated with clinical characteristics.

RESULTS

Distal chromosome 16p11.2 microduplications containing the gene SH2B1 were found in 0.7% of AIS cases (8/1197). We replicated this finding in two additional AIS cohorts (8/1097 and 2/433), resulting in 0.7% (18/2727) of all AIS cases harbouring a chromosome 16p11.2 microduplication, compared with 0.06% of local controls (1/1664) and 0.04% of published controls (8/19584) (p=2.28×10^-11, OR=16.15). Furthermore, examination of electronic health records of 92 455 patients from the Geisinger health system showed scoliosis in 30% (20/66) patients with chromosome 16p11.2 microduplications containing SH2B1 compared with 7.6% (10/132) of controls (p=5.6×10^-4, OR=3.9).

CONCLUSIONS

Recurrent distal chromosome 16p11.2 duplications explain nearly 1% of AIS. Distal chromosome 16p11.2 duplications may contribute to scoliosis pathogenesis by directly impairing growth or by altering expression of nearby genes, such as TBX6. Individuals with distal chromosome 16p11.2 microduplications should be screened for scoliosis to facilitate early treatment.

Common Variant of POC5 Is Associated With the Susceptibility of Adolescent Idiopathic Scoliosis

STUDY DESIGN

A case-control study.

OBJECTIVE

To validate the relationship between POC5 and adolescent idiopathic scoliosis (AIS) in the Chinese patients and to further investigate the functional role of POC5.

SUMMARY OF BACKGROUND DATA

Three rare functional variants in the POC5 were recently reported to be strongly associated with the disease in a large family with multiple members affected with idiopathic scoliosis. To our knowledge, the association between the mutations of POC5 and AIS remains undetermined in the Chinese population.

METHODS

Single nucleotide variants c.1336G>A, c.1286C>T, and c.1363G>C of POC5 were genotyped in 2432 patients with AIS and 2292 healthy controls using multiple ligase detection reactions. Common variants covering POC5 gene were genotyped in 1446 patients and 2080 controls. The mRNA expression of POC5 was determined in the paraspinal muscles collected from 98 patients and 28 controls. The Student t test was used to compare mRNA expression level between the patients and the controls. In addition, the POC5 expression was compared among different genotypes of the remarkably associated single nucleotide polymorphism (SNP) with analysis of variance test.

RESULTS

There was no case of mutation for the three reported variants of POC5. SNP rs6892146 was observed to have significantly different distribution of minor allele frequency in the two group (0.485 vs. 0.446, P = 0.004). The mRNA expression of POC5 was 1.5-fold higher in patients than in the controls (0.00012 ± 0.00009 vs. 0.00008 ± 0.00006, P = 0.02). Patients with genotype GG have a significantly increased expression of POC5 than those with CC (0.00014 ± 0.00007 vs. 0.00009 ± 0.00007, P = 0.03).

CONCLUSION

Common variant rs6892146 of POC5 is associated with the development of AIS in the Chinese population. Targeted regional sequencing of POC5 may help identify novel mutations associated with AIS.

LEVEL OF EVIDENCE

4.

Lack of association between AKAP2 and the susceptibility of adolescent idiopathic scoliosis in the Chinese population

Background

Adolescent idiopathic scoliosis (AIS) is a well characterized spinal deformity that affects millions of children world-wide. The role of genetic factor in the development of AIS has been of great interest, since obvious hereditary trend has been observed in AIS families. In a recent study of Chinese population, a novel mutation of AKAP2 was observed in a family with AIS, which was believed to play a role in the aetiopathogenesis of AIS. The purpose of this study was to investigate whether genetic variants of AKAP2 are associated with the susceptibility of AIS in Chinese population.

Methods

SNV c.2645A > C of AKAP2 was genotyped in 1254 AIS patients and 1232 normal controls using allelic-specific multiple ligase detection reactions. SNPs located within 5′ untranslated regions (UTR) and 3′ UTR of AKAP2 gene were selected using Haploview (v2.6). The GWAS database composed of 961 AIS patients and 1499 controls was referred to for the genotyping information. Relative mRNA expression of AKAP2 in peripheral blood was analyzed for 33 patients and 18 age-matched controls. Comparison between the cases and controls were performed using the Student’s t test. PLINK (v1.90) was used to calculate the association of each SNP with the disease by Cochran-Armitage trend test.

Results

All the patients and the controls presented a genotype of AA in c.2645A > C of AKAP2, and there was no case of mutation in any subject. A total of 116 SNPs covering AKAP2 were analyzed, and none of these SNPs was found to have significantly different allele frequency between the cases and the controls. The mRNA expression of AKAP2 in patients was comparable with that in the controls (1.9 ± 0.8 vs. 1.8 ± 0.7, p = 0.66).

Conclusions

Our large-scale replication study of the variants in AKAP2 gene did not support its association with the susceptibility of AIS in the Chinese population. In future study, functional studies of the previously reported rare variant are warranted to clarify whether the variant can regulate the expression of AKAP2. The whole AKAP2 gene can be sequenced in larger AIS cohorts to identify potentially missing mutations.

New data and features for advanced data mining in Manteia

Manteia is an integrative database available online at http://manteia.igbmc.fr which provides a large array of OMICs data related to the development of the mouse, chicken, zebrafish and human. The system is designed to use different types of data together in order to perform advanced datamining, test hypotheses or provide candidate genes involved in biological processes or responsible for human diseases. In this new version of the database, Manteia has been enhanced with new expression data originating from microarray and next generation sequencing experiments. In addition, the system includes new statistics tools to analyze lists of genes in order to compare their functions and highlight their specific features. One of the main novelties of this release is the integration of a machine learning tool called Lookalike that we have developed to analyze the different datasets present in the system in order to identify new disease genes. This tool identifies the key features of known disease genes to provide and rank new candidates with similar properties from the genome. It is also designed to highlight and take into account the specificities of a disease in order to increase the accuracy of its predictions.