Segregation analysis of Scheuermann disease in ninety families from Siberia

Clinical-genetic analysis of selected genes involved in the development of the human skeleton in 128 Czech patients with suspected congenital skeletal abnormalities

BACKGROUND

Congenital skeletal abnormalities are a heterogeneous group of diseases most commonly associated with small or disproportionate growth, cranial and facial dysmorphisms, delayed bone maturation, etc. Nonetheless, no detailed genotype-phenotype correlation in patients with specific genetic variants is readily available. Ergo, this study focuses on the analysis of patient phenotypes with candidate variants in genes involved in bone growth as detected by molecular genetic analysis.

METHODS

In this study we used molecular genetic methods to analyse the ACAN, COL2A1, FGFR3, IGFALS, IGF1, IGF1R, GHR, NPR2, STAT5B and SHOX genes in 128 Czech children with suspected congenital skeletal abnormalities. Pathogenic variants and variants of unclear clinical significance were identified and we compared their frequency in this study cohort to the European non-Finnish population. Furthermore, a prediction tool was utilised to determine their possible impact on the final protein. All clinical patient data was obtained during pre-test genetic counselling.

RESULTS

Pathogenic variants were identified in the FGFR3, GHR, COL2A1 and SHOX genes in a total of six patients. Furthermore, we identified 23 variants with unclear clinical significance and high allelic frequency in this cohort of patients with skeletal abnormalities. Five of them have not yet been reported in the scientific literature.

CONCLUSION

Congenital skeletal abnormalities may lead to a number of musculoskeletal, neurological, cardiovascular problems. Knowledge of specific pathogenic variants may help us in therapeutic procedures.

Association between spinal curvature disorders and injury: a nationwide population-based retrospective cohort study

OBJECTIVES

Injury is an important issue in public health. Spinal curvature disorders are deformities characterised by excessive curves of the spine. The prevalence of spinal curvature disorders is not low, but its relationship with injury has not been studied. The aim of this study is to investigate whether spinal curvature disorders increase the risk of injury.

DESIGN

Population-based retrospective cohort study.

SETTING

Using data from the Taiwan National Health Insurance Research Database from 2000 to 2010.

PARTICIPANTS AND EXPOSURE

Patients with spinal curvature disorders were selected using codes from the International Classification of Diseases, Ninth Revision, Clinical Modification. A cohort without spinal curvature was randomly frequency-matched to the spinal curvature disorders cohort at a ratio of 2:1 according to age, sex and index year.

PRIMARY OUTCOME MEASURES

The risk of injury was analysed using Cox's proportional hazards regression models adjusting for age, sex, comorbidities, urbanisation level and socioeconomic status.

RESULTS

A total of 20 566 patients with spinal curvature disorders and 41 132 controls were enrolled in this study. The risk of injury was 2.209 times higher (95% CI 2.118 to 2.303) in patients with spinal curvature disorders than in the control group. The spinal curvature disorders cohort exhibited higher risk of developing injury compared with the control group, regardless of age, sex, comorbidities, urbanisation level and subgroup of spinal curvature disorders. Based on the subgroup analysis, the spinal curvature disorders cohort had higher risks of unintentional injury and injury diagnoses such as fracture, dislocation, open wound, superficial injury/contusion, crushing and injury to nerves and spinal cord compared with the control cohort.

CONCLUSIONS

Patients with spinal curvature disorders have a significantly higher risk of developing injury than patients without spinal curvature disorders. Aggressive detection and management of spinal curvature disorders may be beneficial for injury prevention.

An N-Ethyl-N-Nitrosourea (ENU) Mutagenized Mouse Model for Autosomal Dominant Nonsyndromic Kyphoscoliosis Due to Vertebral Fusion

Kyphosis and scoliosis are common spinal disorders that occur as part of complex syndromes or as nonsyndromic, idiopathic diseases. Familial and twin studies implicate genetic involvement, although the causative genes for idiopathic kyphoscoliosis remain to be identified. To facilitate these studies, we investigated progeny of mice treated with the chemical mutagen N-ethyl-N-nitrosourea (ENU) and assessed them for morphological and radiographic abnormalities. This identified a mouse with kyphoscoliosis due to fused lumbar vertebrae, which was inherited as an autosomal dominant trait; the phenotype was designated as hereditary vertebral fusion (HVF) and the locus as Hvf. Micro-computed tomography (μCT) analysis confirmed the occurrence of nonsyndromic kyphoscoliosis due to fusion of lumbar vertebrae in HVF mice, consistent with a pattern of blocked vertebrae due to failure of segmentation. μCT scans also showed the lumbar vertebral column of HVF mice to have generalized disc narrowing, displacement with compression of the neural spine, and distorted transverse processes. Histology of lumbar vertebrae revealed HVF mice to have irregularly shaped vertebral bodies and displacement of intervertebral discs and ossification centers. Genetic mapping using a panel of single nucleotide polymorphic (SNP) loci arranged in chromosome sets and DNA samples from 23 HVF (eight males and 15 females) mice, localized Hvf to chromosome 4A3 and within a 5-megabase (Mb) region containing nine protein coding genes, two processed transcripts, three microRNAs, five small nuclear RNAs, three large intergenic noncoding RNAs, and 24 pseudogenes. However, genome sequence analysis in this interval did not identify any abnormalities in the coding exons, or exon-intron boundaries of any of these genes. Thus, our studies have established a mouse model for a monogenic form of nonsyndromic kyphoscoliosis due to fusion of lumbar vertebrae, and further identification of the underlying genetic defect will help elucidate the molecular mechanisms involved in kyphoscoliosis. © 2018 The Authors. JBMR Plus is published by Wiley Periodicals, Inc. on behalf of the American Society for Bone and Mineral Research.

Familial lumbar Scheuermann disease with idiopathic scoliosis in China: First case report

RATIONALE

Given that Scheuermann disease rarely occurs in the lumbar region and that the co-occurrence of Scheuermann disease and idiopathic scoliosis (IS) has not been reported-the etiology of Scheuermann disease and IS is not clear. In this case report, we present familaiar lumbar Scheuermann disease with IS, in a Chinese proband, who was successfully treated with surgery.

PATIENT CONCERNS

A 16-year-old boy presented at the Second XiangYa Hospital of Central South University with a chief complaint of kyphotic deformity in the lower back for 4 years and obvious lower back pain. In addition, he complained of limited lumbar activity. And The proband's family history was obtained by routine inquiring. In this Chinese family with 17 members over 3 generations. The 3 patients (proband, proband's sister and father) shared the characteristics of vertebral wedging from L1 to L3 and a kyphosis Cobb angle of 37°, 70°, or 73°, respectively. The main deformity of the proband's mother was at T7-L1 with a Cobb angle of 102° in the coronal plane at T7-L1, thoracic kyphosis of 73°, and lumbar lordosis of 62°.

DIAGNOSES

Scheuermann's disease.

INTERVENTIONS

Clinical history, physical examination, laboratory tests, and radiographs of those in the pedigree were recorded, and the related literature was reviewed. The proband accepted osteotomy and orthopedic surgery for treatment.

OUTCOMES

After 3 months of treatment, postoperative lateral radiographs showed a significantly improved sagittal vertical axis (SVA). The other patients were continued to be seen in follow-up visits.

LESSONS

This series of lumbar Scheuermann patients with IS in a pedigree support the genetic contribution to Scheuermann disease. Therefore, this study provides some insight into the genetic etiology of Scheuermann disease with IS.

Mice with an N-Ethyl-N-Nitrosourea (ENU) Induced Tyr209Asn Mutation in Natriuretic Peptide Receptor 3 (NPR3) Provide a Model for Kyphosis Associated with Activation of the MAPK Signaling Pathway

Non-syndromic kyphosis is a common disorder that is associated with significant morbidity and has a strong genetic involvement; however, the causative genes remain to be identified, as such studies are hampered by genetic heterogeneity, small families and various modes of inheritance. To overcome these limitations, we investigated 12 week old progeny of mice treated with the chemical mutagen N-ethyl-N-nitrosourea (ENU) using phenotypic assessments including dysmorphology, radiography, and dual-energy X-ray absorptiometry. This identified a mouse with autosomal recessive kyphosis (KYLB). KYLB mice, when compared to unaffected littermates, had: thoraco-lumbar kyphosis, larger vertebrae, and increased body length and increased bone area. In addition, female KYLB mice had increases in bone mineral content and plasma alkaline phosphatase activity. Recombination mapping localized the Kylb locus to a 5.5Mb region on chromosome 15A1, which contained 51 genes, including the natriuretic peptide receptor 3 (Npr3) gene. DNA sequence analysis of Npr3 identified a missense mutation, Tyr209Asn, which introduced an N-linked glycosylation consensus sequence. Expression of wild-type NPR3 and the KYLB-associated Tyr209Asn NPR3 mutant in COS-7 cells demonstrated the mutant to be associated with abnormal N-linked glycosylation and retention in the endoplasmic reticulum that resulted in its absence from the plasma membrane. NPR3 is a decoy receptor for C-type natriuretic peptide (CNP), which also binds to NPR2 and stimulates mitogen-activated protein kinase (MAPK) signaling, thereby increasing the number and size of hypertrophic chondrocytes. Histomorphometric analysis of KYLB vertebrae and tibiae showed delayed endochondral ossification and expansion of the hypertrophic zones of the growth plates, and immunohistochemistry revealed increased p38 MAPK phosphorylation throughout the growth plates of KYLB vertebrae. Thus, we established a model of kyphosis due to a novel NPR3 mutation, in which loss of plasma membrane NPR3 expression results in increased MAPK pathway activation, causing elongation of the vertebrae and resulting in kyphosis.

Vertebral Scheuermann's disease in Europe: prevalence, geographic variation and radiological correlates in men and women aged 50 and over

In 27 centres across Europe, the prevalence of deforming spinal Scheuermann's disease in age-stratified population-based samples of over 10,000 men and women aged 50+ averaged 8% in each sex, but was highly variable between centres. Low DXA BMD was un-associated with Scheuermann's, helping the differential diagnosis from osteoporosis.

INTRODUCTION

This study aims to assess the prevalence of Scheuermann's disease of the spine across Europe in men and women over 50 years of age, to quantitate its association with bone mineral density (BMD) and to assess its role as a confounder for the radiographic diagnosis of osteoporotic fracture.

METHODS

In 27 centres participating in the population-based European Vertebral Osteoporosis Study (EVOS), standardised lateral radiographs of the lumbar and of the thoracic spine from T4 to L4 were assessed in all those of adequate quality. The presence of Scheuermann's disease, a confounder for prevalent fracture in later life, was defined by the presence of at least one Schmorl's node or irregular endplate together with kyphosis (sagittal Cobb angle >40° between T4 and T12) or a wedged-shaped vertebral body. Alternatively, the (rare) Edgren-Vaino sign was taken as diagnostic. The 6-point-per-vertebral-body (13 vertebrae) method was used to assess osteoporotic vertebral shape and fracture caseness. DXA BMD of the L2-L4 and femoral neck regions was measured in subsets. We also assessed the presence of Scheuermann's by alternative published algorithms when these used the radiographic signs we assessed.

RESULTS

Vertebral radiographic images from 4486 men and 5655 women passed all quality checks. Prevalence of Scheuermann's varied considerably between centres, and based on random effect modelling, the overall European prevalence using our method was 8% with no significant difference between sexes. The highest prevalences were seen in Germany, Sweden, the UK and France and low prevalences were seen in Hungary, Poland and Slovakia. Centre-level prevalences in men and women were highly correlated. Scheuermann's was not associated with BMD of the spine or hip.

CONCLUSIONS

Since most of the variation in population impact of Scheuermann's was unaccounted for by the radiological and anthropometric data, the search for new genetic and environmental determinants of this disease is encouraged.

Genetic epidemiology of Scheuermann's disease

BACKGROUND AND PURPOSE

The genetic/environmental etiology of Scheuermann's disease is unclear. We estimated the heritability of the disease using an etiological model adjusted for sex and time of diagnosis, and examined whether the prevalence of Scheuermann's disease was constant over time.

METHODS

46,418 twins were sent a questionnaire about health and disease. Of these, 75% returned the questionnaire and 97% answered the question "Have you been diagnosed as having Scheuermann's disease by a doctor?"

RESULTS

Responders included 11,436 complete pairs of twins. Data were analysed using classical twin modeling methods. Tetrachoric correlations were used to decide which etiological model to fit. The best-fitting model was the AE model. Heritability was 0.74 (95% CI: 0.65-0.81), while variance explained by environmental factors was 0.26 (95% CI: 0.19-0.35). A threshold of 2.1 (95% CI: 1.9-2.2) was calculated, corresponding to a prevalence of 1.9% (95% CI: 1.3-2.8) for women. Regression coefficients for age and sex were 0.000 (95% CI: -0.003 to 0.002) and -0.32 (95% CI: -0.42 to -0.23).

INTERPRETATION

We found a heritability of 0.74 in Scheuermann's disease. The threshold in men was lower than in women, corresponding to a male prevalence that was almost twice that of females. We found no change in the prevalence of Scheuermann's disease throughout the 50-year age span that we examined.

A major QTL controls susceptibility to spinal curvature in the curveback guppy

Background

Understanding the genetic basis of heritable spinal curvature would benefit medicine and aquaculture. Heritable spinal curvature among otherwise healthy children (i.e. Idiopathic Scoliosis and Scheuermann kyphosis) accounts for more than 80% of all spinal curvatures and imposes a substantial healthcare cost through bracing, hospitalizations, surgery, and chronic back pain. In aquaculture, the prevalence of heritable spinal curvature can reach as high as 80% of a stock, and thus imposes a substantial cost through production losses. The genetic basis of heritable spinal curvature is unknown and so the objective of this work is to identify quantitative trait loci (QTL) affecting heritable spinal curvature in the curveback guppy. Prior work with curveback has demonstrated phenotypic parallels to human idiopathic-type scoliosis, suggesting shared biological pathways for the deformity.

Results

A major effect QTL that acts in a recessive manner and accounts for curve susceptibility was detected in an initial mapping cross on LG 14. In a second cross, we confirmed this susceptibility locus and fine mapped it to a 5 cM region that explains 82.6% of the total phenotypic variance.

Conclusions

We identify a major QTL that controls susceptibility to curvature. This locus contains over 100 genes, including MTNR1B, a candidate gene for human idiopathic scoliosis. The identification of genes associated with heritable spinal curvature in the curveback guppy has the potential to elucidate the biological basis of spinal curvature among humans and economically important teleosts.

Genomic regions associated with kyphosis in swine

BACKGROUND

A back curvature defect similar to kyphosis in humans has been observed in swine herds. The defect ranges from mild to severe curvature of the thoracic vertebrate in split carcasses and has an estimated heritability of 0.3. The objective of this study was to identify genomic regions that affect this trait.

RESULTS

Single nucleotide polymorphism (SNP) associations performed with 198 SNPs and microsatellite markers in a Duroc-Landrace-Yorkshire resource population (U.S. Meat Animal Research Center, USMARC resource population) of swine provided regions of association with this trait on 15 chromosomes. Positional candidate genes, especially those involved in human skeletal development pathways, were selected for SNP identification. SNPs in 16 candidate genes were genotyped in an F2 population (n = 371) and the USMARC resource herd (n = 1,257) with kyphosis scores. SNPs in KCNN2 on SSC2, RYR1 and PLOD1 on SSC6 and MYST4 on SSC14 were significantly associated with kyphosis in the resource population of swine (P ≤ 0.05). SNPs in CER1 and CDH7 on SSC1, PSMA5 on SSC4, HOXC6 and HOXC8 on SSC5, ADAMTS18 on SSC6 and SOX9 on SSC12 were significantly associated with the kyphosis trait in the F2 population of swine (P ≤ 0.05).

CONCLUSIONS

These data suggest that this kyphosis trait may be affected by several loci and that these may differ by population. Carcass value could be improved by effectively removing this undesirable trait from pig populations.

Scheuermann's disease: focus on weight and height role

The aim of this cross-sectional case-control study is the comparison of the weight and height between a group of children with Scheuermann's disease (SD) and a comparable group of healthy ones and also the correlation of them with the degree and the morphology of the kyphotic curve. Following a school-screening program of 10,057 school students, aged between 11 and 17 years old, 175 adolescents with Scheuermann's disease were diagnosed. The mean height and weight of 175 adolescents diagnosed to have SD compared with this of a group of normal children taken randomly from the group of 9,882 healthy children screened. The control group was comparable with the study group concerning age (p = 0.605) and sex. The weight, height and body mass index (BMI) were significantly lower in the healthy (control) group (p < 0.001). However, there was no correlation between weight (r = -0.019, p = 0.804), height (r = 0.053, p = 0.484) and BMI (r = -0.177, p = 0.019) with the magnitude of kyphotic curve. There was also no correlation between weight (r = -0.27, p = 0.722), height (r = -0.025, p = 0.744) and BMI (r = -0.038, p = 0.619) with Voutsinas index as well. Scheuermann's disease is probably a multifactorial skeletal deformity. Weight and height do not seem to affect the magnitude and morphology of the main kyphotic curve in SD. It seems probably that this observation is not part of the pathogenetic mechanism of SD but a result of its cascade. The increased weight and height of these patients may be the secondary result of other disturbances (i.e. hormonal), which may play more crucial role in Scheuermann's disease pathogenesis.

The role of sternum in the etiopathogenesis of Scheuermann disease of the thoracic spine

STUDY DESIGN

A clinical cohort study of sternum clinical measurements was performed in 10,057 students, during a school screening program for Scheuermann disease.

OBJECTIVE

To determine whether the length of sternum is correlated with Scheuermann disease pathogenesis.

SUMMARY OF BACKGROUND DATA

Many theories have been proposed for the etiology of Scheuermann disease, but the true cause remains unclear. Probably mechanical factors play a role in the development of the deformity. The reported success of brace treatment leads to the support to this theory.

METHODS

There were 5048 boys and 5009 girls. The mean age of children was 13,07 years (SD = +/-0.82). Scheuermann disease was detected clinically and was documented with lateral radiograph of spinal column. All children were measured for their sternum's length from the jugular notch until the top of xiphoid process. This measure was repeated 3 times for each child. The height of all students and the arm span were measured, as well.

RESULTS

In total 10,057 students screened, children with Scheuermann disease (study group) were 175 (147 men and 28 women). The length of sternum was greater in the healthy (control) group. There was a statistically significant difference between the 2 groups with regard to the sternum's length (Mann-Whitney U test, P = 0000). This is of particular importance, because in 2 groups that were comparable according to age (Mann-Whitney U test, P = 0605), the children with Scheuermann disease were taller in relation with the control group (Mann-Whitney U test, P = 0000).

CONCLUSION

The smaller length of sternum than the normal has a possible correlation with the appearance of Scheuermann disease. Probably the smaller length of sternum increases the compressive forces on the vertebral endplates anteriorly, allowing uneven growth of the vertebral bodies with wedging. More studies are required for the documentation of this theory of pathogenesis.

Linkage analysis of genetic loci for kyphoscoliosis on chromosomes 5p13, 13q13.3, and 13q32

Kyphoscoliosis, a three-dimensional deformity of spinal growth, is characterized by a curvature in the coronal plane (scoliosis) in conjunction with thoracic kyphosis in excess of the normal range in the sagittal plane. We identified kyphoscoliosis within members of seven families (53 individuals) originally ascertained as part of a large collaborative study of familial idiopathic scoliosis. Model-independent linkage analysis of a genome-wide microsatellite screen identified areas suggestive of linkage on chromosomes 2q22, 5p13, 13q, and 17q11. Single-point and multipoint analyses of an additional 25 flanking microsatellite markers corroborated linkage to these regions, with areas on chromosomes 5p13, 13q13, and 13q32 being the most significant (P < 0.005). Analyses of single nucleotide polymorphism (SNP) markers in the candidate region on chromosome 5 narrowed the region to approximately 3.5 Mb (P < 0.05), with the most significant P values (P < 0.01) occurring in approximately a 1.3-Mb region. Candidate loci in this region include IRX1, IRX2, and IRX4 of the Iroquois Homeobox protein family. On chromosome 13, single-point and multipoint analyses resulted in multiple SNPs having P values < 0.05 within five candidate genes: Osteoblast-specific factor 2 or periostin, forkhead box O1A, A-kinase anchor protein 11, TBC1 domain family member 4, and glypican 5, thus supporting the potential relevance of this region in the pathogenesis of kyphoscoliosis.

Classical Scheuermann disease in male monozygotic twins: further support for the genetic etiology hypothesis

STUDY DESIGN

Classic cases of Scheuermann disease in male monozygotic twins are reported.

OBJECTIVES

To report classic cases of Scheuermann disease or Scheuermann kyphosis in male monozygotic twins, and to discuss the previous two cases of classic Scheuermann disease in monozygotic twins and the genetic etiology theory of Scheuermann kyphosis.

SUMMARY OF BACKGROUND DATA

The etiology of Scheuermann disease remains unclear. Both genetic and mechanical factors or a combination of the two have been postulated to explain Scheuermann disease. The genetic etiology hypothesis has been explained by an autosomal dominant inheritance pattern. In support of this genetic etiology hypothesis, two cases of Scheuermann disease in monozygotic twins have been reported in the English literature.

METHODS

The criteria of Sørensen and Sachs et al were used to diagnose Scheuermann kyphosis. Clinical examination and lateral spinal radiographs were performed on a male monozygotic twin. Both parents were clinically investigated for signs of a kyphotic deformity. RESULTS Scheuermann disease was noted in both patients at the same vertebral levels. The Cobb angle of the kyphosis was 74 degrees and 48 degrees, respectively. Clinical examination of both parents did not show any kyphotic abnormality.

CONCLUSIONS

These cases of classic Scheuermann disease in monozygotic male twins support the theory that there is a genetic contribution in classic Scheuermann disease.