Nosology and classification of genetic skeletal disorders: 2019 revision

Challenges to self-care and domestic life for adults with disproportionate short statured skeletal dysplasia: a mixed method systematic review

PURPOSE

This review aims to assess the impact of pain and limitations across self-care and domestic tasks among adults with disproportionate short statured skeletal dysplasia (SD).

METHODS

A systematic search was conducted across six electronic databases without language or year of publication restrictions from the date of inception of each database through to 31 July 2024. Clear inclusion criteria were established before search initiation and quality assessment was performed using the Mixed Methods Appraisal Tool (MMAT).

RESULTS

Eight studies including 1,114 adults (mean age 33.1 years) met the inclusion criteria, demonstrating high methodological quality (MMAT ranging from 80 to 100%). Challenges in self-care and domestic tasks were prevalent among adults with disproportionate short statured SD. Personal hygiene (65.6%, 95% confidence interval (95%CI): 55.3-74.6%), donning/doffing shoes (54.3%, 95%CI: 38.2-70.0%), and reaching objects (20.2%, 95%CI: 16.8-24.1%) were the most prevalent difficulties, generally falling within low-moderate difficulty. Studies consistently identified mild-intensity pain adversely affected adult's abilities to complete daily activities. Due to the significant heterogeneity of included studies, a meta-analysis was not conducted.

CONCLUSIONS

Adults with disproportionate short statured SD experience challenges in self-care and domestic tasks, alongside a notable trend that suggests a higher prevalence of pain is linked to increased difficulty in completing daily tasks.

Heterozygous mutations in the straitjacket region of the latency-associated peptide domain of TGFB2 cause Camurati-Engelmann disease type II

Camurati-Engelmann disease (CED) is an autosomal dominant bone dysplasia characterized by progressive hyperostosis of the skull base and diaphyses of the long bones. CED is further divided into two subtypes, CED1 and CED2, according to the presence or absence of TGFB1 mutations, respectively. In this study, we used exome sequencing to investigate the genetic cause of CED2 in three pedigrees and identified two de novo heterozygous mutations in TGFB2 among the three patients. Both mutations were located in the region of the gene encoding the straitjacket subdomain of the latency-associated peptide (LAP) of pro-TGF-β2. Structural simulations of the mutant LAPs suggested that the mutations could cause significant conformational changes and lead to a reduction in TGF-β2 inactivation. An activity assay confirmed a significant increase in TGF-β2/SMAD signaling. In vitro osteogenic differentiation experiment using iPS cells from one of the CED2 patients showed significantly enhanced ossification, suggesting that the pathogenic mechanism of CED2 is increased activation of TGF-β2 by loss-of-function of the LAP. These results, in combination with the difference in hyperostosis patterns between CED1 and CED2, suggest distinct functions between TGFB1 and TGFB2 in human skeletal development and homeostasis.

Molecular analysis of 31 cases with fetal skeletal dysplasia

OBJECTIVES

The aim of this study was to describe the prenatal ultrasound findings of fetuses with skeletal dysplasia and to evaluate the genetic variations by molecular genetic analysis.

METHODS

Between August 1, 2018 and March 1, 2023, we conducted a retrospective case series at a tertiary referral center involving patients with fetal skeletal abnormalities. For cases referred for a possible diagnosis of fetal skeletal dysplasia, an ultrasound database and prenatal genetic counseling records were first searched. Terminated cases diagnosed with skeletal dysplasia by pathologic and radiologic findings and cases with skeletal dysplasia proven by postnatal clinical findings were included in the study.

RESULTS

Between 2018 and 2023, a total of 64 cases were diagnosed as skeletal dysplasia based on radiologic findings, pathologic findings, and clinical features. The median week of the first ultrasound performed on patients is 19 0/7 weeks, while the median week of the ultrasound in which skeletal dysplasia is suspected is 21 3/7 weeks. Although micromelia was evaluated as a common feature in all cases, the most common concomitant anomaly was thoracic hypoplasia. Exome sequencing analysis was achieved in 31 (48 %) of cases. In 31 cases, in total of 35 pathogenic single gene mutations and 5 VUS (variants of uncertain significance) variants composing of 23 autosomal dominant, 10 autosomal recessive and 2 X linked recessive mutations were determined.

CONCLUSIONS

Prenatal ultrasound findings can lead us to specific diagnoses, and with the appropriate molecular analysis method, a definitive diagnosis can be made without wasting time and money.

Outcomes of Lower Extremity Total Joint Arthroplasty in Patients With Skeletal Dysplasia: A Systematic Review

Background

Patients with genetic skeletal dysplasias often require lower extremity total joint arthroplasty (TJA) due to early joint degeneration; however, little data exists regarding the outcomes of TJA in this population. Our purpose was to review the literature to determine the complication rates, revision rates, implant survivorship, and patient-reported outcomes of total knee arthroplasty and total hip arthroplasty (THA) in those with genetic skeletal dysplasias.

Methods

A systematic literature review of online databases (PubMed and Google Scholar) was conducted. Studies that reported the outcomes of THA or total knee arthroplasty in patients with genetically confirmed skeletal dysplasias were included. Case reports and studies that defined dysplasia based on height alone were excluded. Fourteen studies met the criteria for data extraction and analysis.

Results

Our review yielded a sample of 596 skeletal dysplasia patients with a median follow-up of 6.01 years (1.7-15.9). Mean age was 54.04 years, and mean body mass index was 29.1 kg/m2. Cementless fixation was utilized in 65.7% of THAs, while all knees were cemented. Hip implant survivorship was 79% at 10 years and 56% at 20 years. Knee implant survivorship was 92% at 10 years and 46% at 20 years. Hip and knee revisions were 15.3% and 13.5%, respectively. The most common indication was aseptic loosening and polyethylene wear. Patient-reported outcomes improved across all domains.

Conclusions

The literature regarding lower extremity TJA in those with genetic skeletal dysplasias demonstrates appropriate 10-year implant survivorship and improvement in patient-reported outcomes across all survey domains.

Further defining the molecular spectrum and long-term follow-up of 17 patients with Dyggve-Melchior-Clausen and Smith-McCort dysplasia type 2

Dyggve-Melchior-Clausen dysplasia (DMC) and Smith-McCort dysplasia (SMC types 1 and 2) are rare spondylo-epi-metaphyseal dysplasias with identical radiological and clinical findings. DMC and SMC type 1 are allelic disorders caused by homozygous or compound heterozygous variants in DYM, while biallelic causative variants in RAB33B lead to SMC type 2. The terminology "skeletal golgipathies" has been recently used to describe these conditions, highlighting the pivotal role of these two genes in the organization and intracellular trafficking of the Golgi apparatus. In this study, we investigated 17 affected individuals (8 males, 9 females) from 10 unrelated consanguineous families, 10 diagnosed with DMC and seven with SMC type 2. The mean age at diagnosis was 9.61 ± 9.72 years, ranging from 20 months to 34 years, and the average height at diagnosis was 92.85 ± 15.50 cm. All patients exhibited variable degrees of short trunk with a barrel chest, protruding abdomen, hyperlordosis, and decreased joint mobility. A total of nine different biallelic variants were identified, with six being located in the DYM gene and the remaining three detected in RAB33B. Notably, five variants were classified as novel, four in the DYM gene and one in the RAB33B gene. This study aims to comprehensively assess clinical, radiological, and molecular findings along with the long-term follow-up findings in 17 patients with DMC and SMC type 2. Our results suggest that clinical symptoms of the disorder typically appear from infancy to early childhood. The central notches of the vertebral bodies were identified as early as 20 months and tended to become rectangular, particularly around 15 years of age. Pseudoepiphysis was observed in five patients; we believe this finding should be taken into consideration when evaluating hand radiographs in clinical assessments. Furthermore, our research contributes to an enhanced understanding of clinical and molecular aspects in these rare "skeletal golgipathies," expanding the mutational spectrum and offering insights into long-term disease outcomes.

The Reliability of Ultrasound Markers in Identifying Fetuses With a Life-Limiting Skeletal Dysplasia

OBJECTIVE

To determine the diagnostic performance of ultrasound markers associated with life-limiting fetal skeletal dysplasia in a fortified cohort.

METHODS

Retrospective review from 2013 to 2023 of pregnancies with suspected fetal skeletal dysplasia. Ultrasound evaluation included measurements predictive of a life-limiting dysplasia: thoracic circumference/abdominal circumference (TC/AC) < 0.6, femur length/abdominal circumference (FL/AC) < 0.16, and thoracic circumference (TC) < 2.5th percentile. Demographics, ultrasound findings, genetic testing, and fetal/neonatal outcome were reviewed.

RESULTS

Of 96 fetuses with complete outcome data, 47 (49%) had a non-life-limiting dysplasia and 49 (51%) had a life-limiting dysplasia. 22 (23%) had no life-limiting markers, 42 (44%) had one, 27 (28%) had two, and 5 (5%) had three. FL/AC < 0.16 and TC < 2.5th percentile were associated with life-limiting dysplasia (p < 0.001; p < 0.001), while TC/AC < 0.6 was rare and did not reach statistical significance (p = 0.056). The positive predictive value (PPV) for predicting life-limiting dysplasia increased from 50% to 78% to 100% with one, two, or three markers. The PPV of the two life-limiting markers was significantly higher in those diagnosed at < versus ≥ 28 weeks (90% vs. 43%, p = 0.02) but the analysis was limited by small numbers in the ≥ 28 weeks cohort. The negative predictive value of no life-limiting markers was 91%.

CONCLUSIONS

In our cohort, the presence of two life-limiting ultrasound markers prior to 28 weeks was highly suggestive of a life-limiting dysplasia, whereas the absence of life-limiting markers was strongly associated with a non-life-limiting dysplasia throughout gestation. Nonetheless, individual markers had a poor predictive value of lethality, and a life-limiting diagnosis ≥ 28 weeks is challenging based on ultrasound markers alone. This highlights the importance of integrating thorough sonography, genetic testing, and balanced parental counseling.

Severe Phenotype With RECQL4 Syndrome: A Report of Two Cases

Baller-Gerold syndrome (BGS, OMIM: 218600), RAPADILINO syndrome (OMIM 266280), and Rothmund-Thomson syndrome (RTS, OMIM 266280), which are caused in some cases by RECQL4 pathogenic variants, show autosomal recessive inheritance. Some refer to them collectively as RECQL4 syndromes. Most cases have been reported during infancy and childhood periods. However, there have been no reports of phenotypes resulting in a lethal course in the perinatal period. We identified two fetuses with biallelic RECQL4 pathogenic variants during the perinatal period. The two fetuses with RECQL4 syndrome showed structural abnormalities, including severely hypoplastic forearms and lower legs. One fetus also had severe pulmonary hypoplasia. One case resulted in neonatal death because of respiratory failure, and the other was artificially terminated during pregnancy. The RECQL4 pathogenic variants were identified by exome sequencing followed by Sanger sequencing. The biallelic RECQL4 pathogenic variants can induce a lethal skeletal disorder.

Antenatal unilateral upper limb acromesomelic dysplasia

Acromesomelic dysplasia (AMD) is an umbrella term given to a heterogeneous group of progressive skeletal disorders characterized by short limbed dwarfism associated with disproportionate shortening of middle and distal segments of the upper as well as lower limbs. Although specific skeletal anomalies are difficult to diagnose antenatally, but because of their antenatal and postnatal implications and a possibility of reoccurrence in following pregnancies, such skeletal anomalies need to be actively addressed. A combination of radiologic, pathologic, genetic and molecular investigation prenatally as well as postnatally is required to classify a specific congenital skeletal dysplasia. Once the genetic make-up of fetal skeletal dysplasia is deciphered, a meaningful genetic counselling could be offered for future pregnancies of affected families. We describe a case of primigravida diagnosed with fetal unilateral upper limb AMD on antenatal ultrasound done at early second trimester. The radius and ulna of left upper limb were abnormally short (less than 5th centile of the mean for that gestational age). The left hand was also hypoplastic. Rest of the sonographic anomaly scan was normal. To the best of our knowledge, AMD limited to unilateral upper limb diagnosed antenatally as an isolated finding is not described in the medical literature so far.

Respiratory insufficiency in an infant with osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a rare presentation in the pediatric population. Whilst orthopedic manifestations are well-publicised, the multiple respiratory complications and mechanisms of respiratory failure in more severe cases are less well described. We report the clinical, radiological and histopathological details of the case of an infant with genetically-confirmed OI (Type 2) and associated respiratory insufficiency, as well as summarise the relevant existing literature. This case highlights the importance of the recognition of clinical challenges associated with the management of respiratory complications in a patient with OI.

Evaluation of functioning and associated factors in children and adolescents with osteogenesis imperfecta

OBJECTIVE

The aim of this study was to evaluate the functioning and associated factors in children and adolescents with osteogenesis imperfecta (OI).

METHODS

This is a cross-sectional study conducted on 30 children and adolescents with OI. Medical records, use of bisphosphonates, socioeconomic status, handgrip strength, balance, joint hypermobility, ambulatory level, and the Pediatric Evaluation of Disability Inventory-Computer Adaptative Test (PEDI-CAT) scores were assessed. Data is presented as mean and standard deviation and Student's t-test or Mann-Whitney U test. Categorical data is presented as frequency and analyzed using Fisher's exact test. Within-group analyses were conducted using ANCOVA or Wilcoxon signed-rank test. Correlations used Kendall's Tau-b test.

RESULTS

The participants involved in this study were 6-18 years old. The sample was separated into two groups according to disease severity. The moderate/severe OI group (n=10) presented a lower height and muscular strength than the mild group (n=20). Muscle weakness was observed in all participants with OI when compared with the normal population. No differences were observed between the groups in the PEDI-CAT scores except for the mobility domain. There were correlations between the PEDI-CAT mobility domain and the number of fractures, OI type, weight, and balance; there was also a correlation between the PEDI-CAT daily activities, mobility, responsibility, and social/cognitive domains.

CONCLUSIONS

The findings suggest that children with moderate/severe forms of OI can achieve the same function levels as children with mild OI. Fractures can have a major influence on the functional level, and treatment should focus on the prevention and rehabilitation of these events when they occur.

Clinical and Genetic Insights into Desbuquois Dysplasia: Review of 111 Case Reports

Skeletal disorders encompass a wide array of conditions, many of which are associated with short stature. Among these, Desbuquois dysplasia is a rare but severe condition characterized by profound dwarfism, distinct facial features, joint hypermobility with multiple dislocations, and unique vertebral and metaphyseal anomalies. Desbuquois dysplasia is inherited in an autosomal recessive manner, with both the DBQD1 (MIM 251450) and DBQD2 (MIM 615777) forms resulting from biallelic mutations. Specifically, DBQD1 is associated with homozygous or compound heterozygous mutations in the CANT1 gene, while DBQD2 can result from mutations in either the CANT1 or XYLT1 genes. This review synthesizes the findings of 111 published case reports, including 54 cases of DBQD1, 39 cases of DBQD2, and 14 cases of the Kim variant (DDKV). Patients in this cohort had a median birth weight of 2505 g, a median length of 40 cm, and a median occipitofrontal circumference of 33 cm. The review highlights the phenotypic variations across Desbuquois dysplasia subtypes, particularly in facial characteristics, joint dislocations, and bone deformities. Genetic analyses revealed a considerable diversity in mutations, with over 35% of cases involving missense mutations, primarily affecting the CANT1 gene. Additionally, approximately 60% of patients had a history of parental consanguinity, indicating a potential genetic predisposition in certain populations. The identified mutations included deletions, insertions, and nucleotide substitutions, many of which resulted in premature stop codons and the production of truncated, likely nonfunctional proteins. These findings underscore the genetic and clinical complexity of Desbuquois dysplasia, highlighting the importance of early diagnosis and the potential for personalized therapeutic approaches. Continued research is essential to uncover the underlying mechanisms of this disorder and improve outcomes for affected individuals through targeted treatments.

Root resorptions induced by genetic disorders: A systematic review

OBJECTIVES

Root resorption in permanent teeth is a common pathological process that often follows dental trauma or orthodontic treatment. More rarely, root resorption is a feature of genetic disorders and can help with diagnosis. Thus, the present review aims to determine which genetic disorders could induce pathological root resorptions and thus which mutated genes could be associated with them.

METHODS

We conducted a systematic review following the PRISMA guidelines. Articles describing root resorptions in patients with genetic disorders were included from PubMed, Embase, Web of Science, and Google Scholar. We synthesized the genetic disorder, the type, severity, and extent of the resorptions, as well as the other systemic and oral symptoms and histological features.

RESULTS

The synthetic analysis included 25 studies among 937 identified records. We analyzed 21 case reports, three case series, and one cohort study. Overall, we highlighted 14 different pathologies with described root resorptions. Depending on the pathology, the sites of resorption, their extent, and their severity showed differences.

CONCLUSION

With 14 genetic pathologies suspected to induce root resorptions, our findings are significant and enrich a previous classification. Among them, three metabolic disorders, three calcium-phosphorus metabolism disorders, and osteolysis disorders were identified.

Clinical utility of comprehensive gene panel testing for common and rare causes of skeletal dysplasia and other skeletal disorders: Results from the largest cohort to date

Molecular genetics enables more precise diagnoses of skeletal dysplasia and other skeletal disorders (SDs). We investigated the clinical utility of multigene panel testing for 5011 unrelated individuals with SD in the United States (December 2019-April 2022). Median (range) age was 8 (0-90) years, 70.5% had short stature and/or disproportionate growth, 27.4% had a positive molecular diagnosis (MDx), and 30 individuals received two MDx. Genes most commonly contributing to MDx were FGFR3 (16.9%), ALPL (13.0%), and COL1A1 (10.3%). Most of the 112 genes associated with ≥1 MDx were primarily involved in signal transduction (n = 35), metabolism (n = 23), or extracellular matrix organization (n = 17). There were implications associated with specific care/treatment options for 84.4% (1158/1372) of MDx-positive individuals; >50% were linked to conditions with targeted therapy approved or in clinical development, including osteogenesis imperfecta, achondroplasia, hypophosphatasia, and mucopolysaccharidosis. Forty individuals with initially inconclusive results became MDx-positive following family testing. Follow-up mucopolysaccharidosis enzyme activity testing was positive in 14 individuals (10 of these were not MDx-positive). Our findings showed that inclusion of metabolic genes associated with SD increased the clinical utility of a gene panel and confirmed that integrated use of comprehensive gene panel testing with orthogonal testing reduced the burden of inconclusive results.

Metabolic Bone Disease

Metabolic bone diseases encompass a group of disorders characterized by abnormalities in bone metabolism, structure, or mineralization. These disorders negatively impact overall health and quality of life and place individuals at high risk for fracture, which may increase morbidity and mortality. Clinicians should understand who is at risk for these disorders, select individuals who warrant further workup, determine appropriate laboratory and imaging evaluation, interpret results in a clinical context, and choose an optimal management strategy based on the individual patient.

Involvement of kinesins in skeletal dysplasia: a review

Skeletal dysplasias are group of rare genetic diseases resulting from mutations in genes encoding structural proteins of the cartilage extracellular matrix (ECM), signaling molecules, transcription factors, epigenetic modifiers, and several intracellular proteins. Cell division, organelle maintenance, and intracellular transport are all orchestrated by the cytoskeleton-associated proteins, and intracellular processes affected through microtubule-associated movement are important for the function of skeletal cells. Among microtubule-associated motor proteins, kinesins in particular have been shown to play a key role in cell cycle dynamics, including chromosome segregation, mitotic spindle formation, and ciliogenesis, in addition to cargo trafficking, receptor recycling, and endocytosis. Recent studies highlight the fundamental role of kinesins in embryonic development and morphogenesis and have shown that mutations in kinesin genes lead to several skeletal dysplasias. However, many questions concerning the specific functions of kinesins and their adaptor molecules as well as specific molecular mechanisms in which the kinesin proteins are involved during skeletal development remain unanswered. Here we present a review of the skeletal dysplasias resulting from defects in kinesins and discuss the involvement of kinesin proteins in the molecular mechanisms that are active during skeletal development.

Molecular Heterogeneity of Osteopetrosis in India: Report of 17 Novel Variants

Osteopetrosis is a clinically and genetically heterogeneous group of inherited bone disorders that is caused by defects in osteoclast formation or function. Treatment options vary with the disease severity and an accurate molecular diagnosis helps in prognostication and treatment decisions. We investigated the genetic causes of osteopetrosis in 31 unrelated patients of Indian origin. Screening for the genetic variants was done by Sanger sequencing or next generation sequencing in 48 samples that included 31 samples from index patients, 16 from parents' and 1 chorionic villus sample. A total of 30 variants, including 29 unique variants, were identified in 26 of the 31 patients in the study. TCIRG1 was the most involved gene (n = 14) followed by TNFRSF11A (n = 4) and CLCN7 (n = 3). A total of 17 novel variants were identified. Prenatal diagnosis was done in one family and the foetus showed homozygous c.807 + 2T > G variant in TCIRG1. Molecular diagnosis of osteopetrosis aids in therapeutic decisions including the need for a stem cell transplantation and gives a possible option of performing prenatal diagnosis in affected families. Further studies would help in understanding the genetic etiology in patients where no variants were identified.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12288-023-01732-4.

A novel variant in IFT122 associated with a severe phenotype of cranioectodermal dysplasia

A 27-year-old multiparous woman conceived her fetus naturally. Early second-trimester ultrasound showed short extremities with systemic subcutaneous edema. The pregnancy was artificially terminated at 19 weeks of gestation because of the abnormalities based on the parents' wishes. The parents desired whole-exome sequencing to detect a causative gene using the umbilical cord and the parents' saliva. Compound heterozygous variants (NC_000003.11(NM_052989.3):c.230 T > G/NC_000003.11(NM_052985.4):c.1178A > T) were identified. We described a fetus with a novel compound heterozygous variant in IFT122. The phenotype of this case was severer than of other types of cranioectodermal dysplasia.

The effect of antibiotic-impregnated calcium sulfate beads and Medical Optimization Clinic attendance on the acute surgical site infection rate in high-risk pediatric neuromuscular and syndromic scoliosis patients

BACKGROUND

Neuromuscular and syndromic (NMS) scoliosis patients are at higher risk of acute surgical site infections (SSIs). Despite following POSNA's endorsed consensus-based guidelines for SSI prevention, our institutional rates of acute SSI have varied dramatically. This variability drove simultaneous strategies to lower SSI rates: the creation of a preoperative Medical Optimization Clinic (MOC) and use of antibiotic-impregnated (Abx-I) calcium sulfate beads.

METHODS

Patients undergoing index PSF at a single institution between 2016 and 2022 were retrospectively reviewed. Patients with ≥ 2 risk factors were included: (1) BMI < 18.5 or > 25; (2) incontinence; (3) instrumentation to pelvis; (4) non-verbal; (5) GMFCS IV/V. SSI was defined as deep infection within 90 days. We compared patients who attended MOC and received Abx-I (MOC + Abx-I) to those receiving neither intervention (control) nor a single intervention.

RESULTS

282 patients were included. The overall infection rate was 4.26%. Higher GMFCS (p = 0.0147), non-verbal status (p = 0.0048), and longer fusions (p = 0.0298) were independently associated with infection rate. Despite the MOC + Abx-I group having larger Cobb angles (88° ± 26°), higher GMFCS levels (4.5 ± 0.9), ASA class (3 ± 0.4), and more frequent instrumentation to the pelvis (85%), they had the lowest infection rate (2.13%) when compared to the control (4.2%) or single intervention groups (5.7%, 4.6%) (p = 0.9).

CONCLUSION

The study examined the modern infection rate of NMS patients following the implementation of two interventions: MOC and Abx-I. Despite having higher risk factors (curves (88°), GMFCS level (4.5), ASA class (3), higher % instrumentation to the pelvis (85%)), the patients treated with both interventions demonstrated the lowest infection rate (2.13%).

Safety and Efficacy of Denosumab in Children With Osteogenesis Imperfecta-the First Prospective Comparative Study

CONTEXT

Denosumab is a potential therapeutic agent for osteogenesis imperfecta (OI), but its efficacy and safety remain unclear in children with OI.

OBJECTIVE

We aimed to investigate the effects of denosumab on bone mineral density (BMD), spinal morphometry, and safety in children with OI compared with zoledronic acid.

METHODS

In this prospective study, 84 children or adolescents with OI were randomized to receive denosumab subcutaneous injection every 6 months or zoledronic acid intravenous infusion once. Changes of BMD and its Z-score, vertebral shape, serum levels of calcium and bone turnover biomarkers were assessed during the 1-year treatment.

RESULTS

After 12 months of treatment, BMD at the lumbar spine, femoral neck, and total hip significantly increased by 29.3%, 27.8%, and 30.2% in the denosumab group, and by 32.2%, 47.1%, and 41.1% in the zoledronic acid group (all P < .001 vs baseline). Vertebral height and projection area significantly increased after denosumab and zoledronic acid treatment. Rebound hypercalcemia was found to be a common and serious side effect of denosumab, of which 14.3% reached hypercalcemic crisis. Rebound hypercalcemia could be alleviated by switching to zoledronic acid treatment.

CONCLUSION

Treatment with denosumab or zoledronic acid is beneficial in increasing BMD and improving the spinal morphometry of children with OI. However, denosumab should be used with caution in pediatric patients with OI because of its common and dangerous side effect of rebound hypercalcemia. The appropriate dosage and dosing interval of denosumab need to be further explored in children with OI.

Resilience and coping: a qualitative analysis of cognitive and behavioral factors in adults with osteogenesis Imperfecta

PURPOSE

The aim of this qualitative study was to investigate resilience among adults with Osteogenesis Imperfecta (OI).

MATERIALS AND METHODS

Semi-structured interviews were conducted with 15 adults with OI. Transcripts were coded and subsequently abstracted, yielding themes specific to resilience and coping. Interview guides covered broad topics including pain challenges specific to OI, mental health issues related to OI, and priorities for future interventions for individuals with OI.

RESULTS

Participants described resilience in the context of OI as the ability to grow from adversity, adapt to challenges resulting from OI-related injuries, and find identities apart from their condition. Psychological coping strategies included acceptance, self-efficacy, cognitive reframing, perspective-taking, and positivity. Behavioral factors that helped participants develop resilience included developing new skills, pursuing meaningful goals, practicing spirituality, and seeking external resources such as psychotherapy, education, and connection with community.

CONCLUSION

Having identified how adults with OI define resilience and the strategies they use to cope, we can now develop interventions and guide healthcare providers in improving psychological wellbeing in this population.

Osteopetrosis in the pediatric patient: what the radiologist needs to know

Osteopetrosis describes several types of rare sclerosing bone dysplasias of varying clinical and radiographic severity. The classic autosomal dominant subtype emerges most often in adolescence but can present from infancy through adulthood. The autosomal recessive osteopetrosis, or "malignant infantile osteopetrosis," presents in infancy with a grimmer prognosis, though the autosomal dominant forms (often mislabeled as "benign") actually can have life-threatening consequences as well. Often osteopetrosis is detected due to skeletal findings on radiographs performed to evaluate injury or as an incidental finding during evaluation for illness. Given the varied phenotypic severity and presentations at different ages, radiologists play an integral role in the care of these patients both in diagnosis and in clinical evaluation and monitoring. A deeper understanding of the underlying genetic basis of the disease can aid in the radiologist in diagnosis and in anticipation of unique complications. An overview of current clinical management is also discussed.

Outcomes after completing growth-friendly surgical treatment for early-onset scoliosis in patients with skeletal dysplasia

Aims

The aim of this study was to compare outcomes after growth-friendly treatment for early-onset scoliosis (EOS) between patients with skeletal dysplasias versus those with other syndromes.

Methods

We retrospectively identified 20 patients with skeletal dysplasias and 292 with other syndromes (control group) who had completed surgical growth-friendly EOS treatment between 1 January 2000 and 31 December 2018. We compared radiological parameters, complications, and health-related quality of life (HRQoL) at mean follow-up of 8.6 years (SD 3.3) in the dysplasia group and 6.6 years (SD 2.6) in the control group.

Results

Mean major curve correction per patient did not differ significantly between the dysplasia group (43%) and the control group (28%; p = 0.087). Mean annual spinal height increase was less in the dysplasia group (9.3 mm (SD 5.1) than in the control group (16 mm (SD 9.2); p < 0.001). Mean annual spinal growth adjusted to patient preoperative standing height during the distraction period was 11% in the dysplasia group and 14% in the control group (p = 0.070). The complication rate was 1.6 times higher (95% confidence interval (CI) 1.3 to 2.0) in the dysplasia group. The following complications were more frequent in the dysplasia group: neurological injury (rate ratio (RR) 5.1 (95% CI 2.3 to 11)), deep surgical site infection (RR 2.2 (95% CI 1.2 to 4.1)), implant-related complications (RR 2.0 (95% CI 1.5 to 2.7)), and unplanned revision (RR 1.8 (95% CI 1.3 to 2.5)). Final fusion did not provide additional spinal height compared with watchful waiting (p = 0.054). There were no significant differences in HRQoL scores between the groups.

Conclusion

After growth-friendly EOS treatment, patients with skeletal dysplasias experienced a higher incidence of complications compared to those with other syndromes. Surgical growth-friendly treatment for skeletal dysplasia-associated EOS should be reserved for patients with severe, progressive deformities that are refractory to nonoperative treatment.

A novel entity of massive multifocal osteolyses in the elderly

Osteolyses are common findings in elderly patients and most frequently represent malignant or locally aggressive bone tumors, infection, inflammatory and endocrine disorders, histiocytoses, and rare diseases such as Gorham-Stout syndrome. We here report on a novel entity of massive multifocal osteolyses in both shoulders, the right hip and left knee joint and the dens of an 83-year-old patient not relatable to any previously known etiopathology of bone disorders. The soft tissue mass is of myxoid stroma with an unspecific granulomatous inflammatory process, aggressively destroying extensive cortical and cancellous bone segments and encroaching on articulating bones in diarthrodial large joints. Radiological, nuclear medical, serological, histological, and immunohistochemical analyses were incapable of further classifying the disease pattern within the existing scheme of pathology. Quantitative polymerase chain reaction and next generation sequencing revealed that mutations are not suggestive of any known hereditary or acquired bone disease. Possible treatment options include radionuclide therapy for pain palliation and percutaneous radiation to arrest bone resorption while surgical treatment is inevitable for pathological fractures. This case study shall increase the awareness of the musculoskeletal community and motivate to collect further information on this rare but mutilating disorder.

Pregnancy complicated by severe osteogenesis imperfecta poses a challenge for the anaesthetist: A case report

Pregnant women with severe osteogenesis imperfecta (OI) are uncommon, and there are limited data regarding anaesthesia for caesarean section in these high-risk individuals. The presence of anatomical and physiological abnormalities can pose technical challenges for the anaesthetist. This report describes the successful implementation of epidural anaesthesia in a parturient with severe OI. To our knowledge, this is the first documented use of ultrasound-assisted neuraxial anaesthesia and wrist blood pressure monitoring in such patients undergoing caesarean section. Understanding the pathophysiological changes associated with OI is crucial for ensuring safe administration of anaesthesia to these women.

Prenatal ultrasound findings and prenatal diagnosis of fetal skeletal dysplasia

OBJECTIVE

To analyze the value of prenatal ultrasound and molecular testing in diagnosing fetal skeletal dysplasia (SD).

METHODS

Clinical data, prenatal ultrasound data, and molecular results of pregnant women with fetal SD were collected in the ultrasound department of our clinic from May 2019 to December 2021.

RESULTS

A total of 40 pregnant women with fetal SD were included, with 82.5% exhibiting short limb deformity, followed by 25.0% with central nervous system malformations, 17.50% with facial malformations, 15% with cardiac malformations, and 12.5% with urinary system malformations. The genetic testing positive rate was 70.0% (28/40), with 92.8% (26/28) being single-gene disorders due to mutations in FGFR3, COL1A1, COL1A2, EVC2, FLNB, LBR, and TRPV4 genes. The most common SD subtypes were osteogenesis imperfecta (OI), thanatophoric dysplasia (TD), and achondroplasia (ACH). The gestational age (GA) at initial diagnosis for TD, OI, and ACH was 16.6, 20.9, and 28.3 weeks, respectively (p < 0.05), with no significant difference in femoral shortening between the three groups (p > 0.05). Of the OI cases, 5 out of 12 had a family history.

CONCLUSION

Short limb deformity is the most prevalent phenotype of SD. When fetal SD is suspected, detailed ultrasound screening should be conducted, combined with GA at initial diagnosis, family history, and molecular evidence, to facilitate more accurate diagnosis and enhance prenatal counseling and perinatal management.

Prenatal diagnosis of a skeletal disorder characterized by rhizomelic shortening of limbs caused by compound heterozygous variants in the PKDCC gene: Case report and literature review

BACKGROUND

The protein kinase domain containing cytoplasmic (PKDCC) gene (OMIM#618821) is associated with bone development. Biallelic variants in the PKDCC gene can cause rhizomelic limb shortening with dysmorphic features.

CASE REPORT

A fetus was found to be rhizomelic limb shortening at 16 weeks of gestation and amniocentesis was performed at 19 weeks of gestation. Genomic DNA extracted from the amniotic fluid was subjected to chromosomal microarray analysis (CMA), and Trio-total whole-exome sequencing (Trio-WES). Sanger sequencing was used to verify the candidate pathogenic variants. CMA was normal, while Trio-WES identified two compound heterozygous variants in the PKDCC gene, namely c.417_c.423delCGGCGCG insTCATGGGCTCAGTACAC(p.G140fs*35) and c.345G>A (p.W115*,379). Then the fetus was aborted and the development of its bone cells were compared with that of a normal fetus of similar gestational age by histopathological examination. Clinical findings of the fetus were shortening humerus and femur, synophrys, much hair on the side face, simian line on the right palm, etc. Histopathological examination showed that the affected fetus had increased proliferative chondrocytes, widened proliferative bands, and delayed bone mineralization.

CONCLUSIONS

We reported a prenatal case of rhizomelic shortening of limbs caused by compound heterozygous variants in the PKDCC gene, which emphasized the important role of Trio-WES for diagnosis of skeletal dysplasia in fetuses.

Role of genetic investigation in the diagnosis of short stature in a cohort of Italian children

BACKGROUND

Short stature (SS) is defined as height more than 2 standard deviations below the mean for age and sex. Hypothyroidism, celiac disease, growth hormone deficiency, hormonal abnormalities, and genetic conditions are among its causes. A wide range of conditions often due to largely unknown genetic variants can elude conventional diagnostic workup.

AIM

We used next-generation sequencing (NGS) to better understand the etiology of SS in a cohort of Italian children.

PATIENTS AND METHODS

The study sample was 125 children with SS of unknown origin referred to our Institute between 2015 and 2021. All had undergone complete auxological and hormonal investigations to exclude common causes of SS. Genetic analysis was performed using a NGS panel of 104 genes. Clinical data were reviewed to clarify the pathogenicity of the variants detected.

RESULTS

In this cohort, 43 potentially causing variants were identified in 38 children. A syndromic genetic condition was diagnosed in 7: Noonan syndrome in 3, Leri-Weill syndrome in 3, and hypochondroplasia in 1. Moreover, 8 benign variants and other 37 like benign variants were found. In 88 children, 179 variants of uncertain significance (VUS) were identified. No variant was found in 16 children.

CONCLUSION

Genetic analysis is a useful tool in the diagnostic workup of patients with SS, in adapting management and treatment, and in identifying syndromes with mild atypical clinical features. The role of VUS should not be underestimated, particularly when multiple VUS with possible mutual worsening effects are present in the same child.

Osteomesopyknosis associated with a novel ALOX5 variant that impacts the RANKL pathway

BACKGROUND

Bone tissue homeostasis relies on the coordinated activity of the bone-forming osteoblasts and bone-resorbing osteoclasts. Osteomesopyknosis is considered a distinctive rare sclerosing skeletal disorder of unelucidated pathophysiology and presumably autosomal dominant transmission. However, the causal genes are unknown.

METHODS

We present a case report encompassing clinical assessments, imaging studies, and whole-exome sequencing analysis, complemented by functional in vitro experiments.

RESULTS

This new case of osteomesopyknosis was associated with a missense ALOX5 variant predicted to induce protein misfolding and proteasomal degradation. Transfection experiments demonstrated that the variant was associated with reduced protein levels restored by proteasomal inhibition with bortezomib. Likewise, gene expression analysis showed that the mutated gene was associated with a decreased RANKL/OPG ratio, which is a critical driver of osteoclast precursor differentiation.

CONCLUSION

Our data indicate impaired bone resorption as the underlying mechanism of this rare osteosclerosis, implicating ALOX5 pathogenic variants as potential etiological factors.

Pathogenic variants affecting the TB5 domain of the fibrillin-1 protein: not only in geleophysic/acromicric dysplasias but also in Marfan syndrome

BACKGROUND

Marfan syndrome (MFS) is a multisystem disease with a unique combination of skeletal, cardiovascular and ocular features. Geleophysic/acromicric dysplasias (GPHYSD/ACMICD), characterised by short stature and extremities, are described as 'the mirror image' of MFS. The numerous FBN1 pathogenic variants identified in MFS are located all along the gene and lead to the same final pathogenic sequence. Conversely, in GPHYSD/ACMICD, the 28 known heterozygous FBN1 pathogenic variants all affect exons 41-42 encoding TGFβ-binding protein-like domain 5 (TB5).

METHODS

Since 1996, more than 5000 consecutive probands have been referred nationwide to our laboratory for molecular diagnosis of suspected MFS.

RESULTS

We identified five MFS probands carrying distinct heterozygous pathogenic in-frame variants affecting the TB5 domain of FBN1. The clinical data showed that the probands displayed a classical form of MFS. Strikingly, one missense variant affects an amino acid that was previously involved in GPHYSD.

CONCLUSION

Surprisingly, pathogenic variants in the TB5 domain of FBN1 can lead to two opposite phenotypes: GPHYSD/ACMICD and MFS, suggesting the existence of different pathogenic sequences with the involvement of tissue specificity. Further functional studies are ongoing to determine the precise role of this domain in the physiopathology of each disease.

ERN BOND: The key European network leveraging diagnosis, research, and treatment for rare bone conditions

There is no universally accepted definition for rare diseases: in Europe a disease is considered to be rare when affecting fewer than 1 in 2000 people. European Reference Networks (ERNs) have been the concrete response to address the unmet needs of rare disease patients and many pan-European issues in the field, reducing inequities, and significantly increasing accessibility to high-quality healthcare across Europe. ERNs are virtual networks, involving centres and patient representatives with the general scope to facilitate discussion on complex cases requiring highly specialised competences and trained expertise. ERN BOND - the European Reference Network on rare BONe Diseases - is one of these 24 approved networks with the specific ongoing mission to implement measures facilitating multidisciplinary, holistic, continuous, patient-centred, and participative care provision to patients, and supporting them in the full realisation of their fundamental human rights. ERN BOND includes in 2023 a total of 53 centres of expertise from 20 European countries. Its governing structure installed in March 2017 includes decision-making, operative and consultative committees, which comprise experts in the field and patient representatives ensuring patient's voice and perspectives are taken into account. Over the years, ERN BOND has worked hard to achieve its mission and valuably contribute to the advancement of diagnosis, management, treatment, and research in rare diseases. The network activities are mainly related to (i) the provision of care which collectively involves averagely 2800 patients diagnosed per year, (ii) the development of education for and training of the healthcare personnel consisting until now in the realisation of 7 thematic workshops and 19 webinars, (iii) the dissemination and exchange and spread of knowledge via network's website (https://ernbond.eu/), social media channels, and newsletters, (iv) the management of related data through a disease registry currently mapping over 2300 cases and recording over 600 reported cases, and (v) the enhancement of research which now include two clinical trials endorsed by the network. ERN BOND represents therefore an unprecedented move to improve the healthcare management of patients suffering from rare bone diseases through European collaborations. This network, through the support from the European Health Programme, will continue to pursue its efforts to achieve its goals, always maintaining the patients and their families at the centre of healthcare services.

The molecular complexity of COL2A1 splicing variants and their significance in phenotype severity

Pathogenic single nucleotide variants (SNVs) found in the COL2A1 gene are associated with a broad range of skeletal dysplasias due to their impact on the structure and function of the Col2a1 protein. However, the molecular mechanisms of some nucleotide variants detected during diagnostic testing remain unclear. The interpretation of missense and splicing variants caused by SNVs poses a significant challenge for clinicians. In this work, we analyzed 22 splicing variants in the COL2A1 gene which have been found in patients with COL2A1-associated skeletal dysplasias. Using a minigene system, we investigated the impact of these SNVs on splicing and gained insights into their molecular mechanisms and genotype-phenotype correlations for each patient. The results of our study are very useful for improving the accuracy of diagnosis and the management of patients with skeletal dysplasias caused by SNVs in the COL2A1 gene.

Zebrafish as a model to investigate a biallelic gain-of-function variant in MSGN1, associated with a novel skeletal dysplasia syndrome

BACKGROUND/OBJECTIVES

Rare genetic disorders causing specific congenital developmental abnormalities often manifest in single families. Investigation of disease-causing molecular features are most times lacking, although these investigations may open novel therapeutic options for patients. In this study, we aimed to identify the genetic cause in an Iranian patient with severe skeletal dysplasia and to model its molecular function in zebrafish embryos.

RESULTS

The proband displays short stature and multiple skeletal abnormalities, including mesomelic dysplasia of the arms with complete humero-radio-ulna synostosis, arched clavicles, pelvic dysplasia, short and thin fibulae, proportionally short vertebrae, hyperlordosis and mild kyphosis. Exome sequencing of the patient revealed a novel homozygous c.374G > T, p.(Arg125Leu) missense variant in MSGN1 (NM_001105569). MSGN1, a basic-Helix-Loop-Helix transcription factor, plays a crucial role in formation of presomitic mesoderm progenitor cells/mesodermal stem cells during early developmental processes in vertebrates. Initial in vitro experiments show protein stability and correct intracellular localization of the novel variant in the nucleus and imply retained transcription factor function. To test the pathogenicity of the detected variant, we overexpressed wild-type and mutant msgn1 mRNA in zebrafish embryos and analyzed tbxta (T/brachyury/ntl). Overexpression of wild-type or mutant msgn1 mRNA significantly reduces tbxta expression in the tailbud compared to control embryos. Mutant msgn1 mRNA injected embryos depict a more severe effect, implying a gain-of-function mechanism. In vivo analysis on embryonic development was performed by clonal msgn1 overexpression in zebrafish embryos further demonstrated altered cell compartments in the presomitic mesoderm, notochord and pectoral fin buds. Detection of ectopic tbx6 and bmp2 expression in these embryos hint to affected downstream signals due to Msgn1 gain-of-function.

CONCLUSION

In contrast to loss-of-function effects described in animal knockdown models, gain-of-function of MSGN1 explains the only mildly affected axial skeleton of the proband and rather normal vertebrae. In this context we observed notochord bending and potentially disruption of pectoral fin buds/upper extremity after overexpression of msgn1 in zebrafish embryos. The latter might result from Msgn1 function on mesenchymal stem cells or on chondrogenesis in these regions. In addition, we detected ectopic tbx6 and bmp2a expression after gain of Msgn1 function in zebrafish, which are interconnected to short stature, congenital scoliosis, limb shortening and prominent skeletal malformations in patients. Our findings highlight a rare, so far undescribed skeletal dysplasia syndrome associated with a gain-of-function mutation in MSGN1 and hint to its molecular downstream effectors.

The health-care utilization and economic burden in patients with genetic skeletal disorders

BACKGROUND

Most genetic skeletal disorders (GSD) were complex, disabling and life-threatening without effective diagnostic and treatment methods. However, its impacts on health system have not been well studied. The study aimed to systematically evaluate the health-care utilization and economic burden in GSD patients.

METHODS

The patients were derived from 2018 Nationwide Inpatient Sample and Nationwide Readmissions Database. GSD patients were extracted based on International Classification of Diseases-10th revision codes.

RESULTS

A total of 25,945 (0.12%) records regarding GSD were extracted from all 21,400,282 records in NIS database. GSD patients were likely to have significantly longer length of stay (6.50 ± 0.08 vs. 4.63 ± 0.002, P < 0.001), higher total charges ($85,180.97 ± 1,239.47 vs. $49,884.26 ± 20.99, P < 0.001), suffering more procedure, diagnosis and transferring records in comparison to patients with common conditions. GSD patients had a significantly higher 30-day all-cause readmission rate based on Nationwide Readmissions Database.

CONCLUSIONS

The heavy health-care utilization and economic burden emphasized the urgency for policy leaders, scientific and pharmaceutical researchers, health care providers and employers to identify innovative ways and take effective measurements immediately, and eventually to help improve the care, management, and treatment of these devastating diseases.

Indian patients with CHST3-related chondrodysplasia with congenital joint dislocations

CHST3-related chondrodysplasia with congenital joint dislocations (CDCJD, #MIM 143095), is a rare genetic skeletal disorder caused by biallelic loss of function variants in CHST3. CHST3 is critical for the sulfation of chondroitin sulfate. This study delineates the clinical presentation of nine individuals featuring the key symptoms of CDCJD; congenital joint (knee and elbow) dislocations, short trunk short stature progressive vertebral anomalies, and metacarpal shortening. Additional manifestations include irregular distal femoral epiphysis, supernumerary carpal ossification centers, bifid humerus, club foot, and cardiac abnormalities. Sanger sequencing was carried out to investigate molecular etiology in eight patients and exome sequencing in one. Genetic testing revealed five homozygous variants in CHST3 (four were novel and one was previously reported). All these variants are located on sulfotransferase domain of CHST3 protein and were classified as pathogenic/ likely pathogenic. We thus report on nine individuals with CHST3-related chondrodysplasia with congenital joint dislocations from India and suggest monitoring the health of cardiac valves in this condition.

Aggrecan-related bone disorders; a novel heterozygous ACAN variant associated with spondyloepimetaphyseal dysplasia expanding the phenotypic spectrum and review of literature

BACKGROUND

Spondyloepimetaphyseal dysplasias (SEMD) are a large group of skeletal disorders represented by abnormalities of vertebrae in addition to epiphyseal and metaphyseal areas of bones. Several genes have been identified underlying different forms. ACAN gene mutations were found to cause Aggrecan-related bone disorders (spondyloepimetaphyseal dysplasias,spondyloepiphyseal dysplasias, familial osteochondritis dissecans and short stature syndromes). This study aims to find the disease causing variant in Egyptian patient with SEMD using whole exome sequencing.

METHODS

Whole-exome sequencing was performed for an Egyptian male patient who presented with short stature, clinical and radiological features suggestive of unclassified SEMD.

RESULTS

The study identified a novel de novo heterozygous ACAN gene variant (c.7378G>A; p.Gly2460Arg) in G3 domain. Mutations in ACAN gene have been more commonly associated with short stature than SEMD. The phenotype of our patient was intermediate in severity between spondyloepiphyseal dysplasia presentation; Kimberley type(SEDK) and Spondyloepimetaphyseal dysplasias Aggrecan (SEMDAG) CONCLUSIONS: Whole exome sequencing revealed a novel de novo ACAN gene variant in patient with SEDK. The clinical and skeletal phenotype of our patient was much severe than those reported originally and showed more metaphyseal involvement. To the best of our knowledge, two previous studies reported a heterozygous variant in ACAN with spondyloepiphyseal dysplasia presentation; Kimberley type.

Skeletal growth is enhanced by a shared role for SOX8 and SOX9 in promoting reserve chondrocyte commitment to columnar proliferation

SOX8 was linked in a genome-wide association study to human height heritability, but roles in chondrocytes for this close relative of the master chondrogenic transcription factor SOX9 remain unknown. We undertook here to fill this knowledge gap. High-throughput assays demonstrate expression of human SOX8 and mouse Sox8 in growth plate cartilage. In situ assays show that Sox8 is expressed at a similar level as Sox9 in reserve and early columnar chondrocytes and turned off when Sox9 expression peaks in late columnar and prehypertrophic chondrocytes. Sox8-/- mice and Sox8fl/flPrx1Cre and Sox9fl/+Prx1Cre mice (inactivation in limb skeletal cells) have a normal or near normal skeletal size. In contrast, juvenile and adult Sox8fl/flSox9fl/+Prx1Cre compound mutants exhibit a 15 to 20% shortening of long bones. Their growth plate reserve chondrocytes progress slowly toward the columnar stage, as witnessed by a delay in down-regulating Pthlh expression, in packing in columns and in elevating their proliferation rate. SOX8 or SOX9 overexpression in chondrocytes reveals not only that SOX8 can promote growth plate cell proliferation and differentiation, even upon inactivation of endogenous Sox9, but also that it is more efficient than SOX9, possibly due to greater protein stability. Altogether, these findings uncover a major role for SOX8 and SOX9 in promoting skeletal growth by stimulating commitment of growth plate reserve chondrocytes to actively proliferating columnar cells. Further, by showing that SOX8 is more chondrogenic than SOX9, they suggest that SOX8 could be preferred over SOX9 in therapies to promote cartilage formation or regeneration in developmental and degenerative cartilage diseases.

Relevance of Extending FGFR3 Gene Analysis in Osteochondrodysplasia to Non-Coding Sequences: A Case Report

Skeletal dysplasia, also called osteochondrodysplasia, is a category of disorders affecting bone development and children's growth. Up to 552 genes, including fibroblast growth factor receptor 3 (FGFR3), have been implicated by pathogenic variations in its genesis. Frequently identified causal mutations in osteochondrodysplasia arise in the coding sequences of the FGFR3 gene: c.1138G>A and c.1138G>C in achondroplasia and c.1620C>A and c.1620C>G in hypochondroplasia. However, in some cases, the diagnostic investigations undertaken thus far have failed to identify the causal anomaly, which strengthens the relevance of the diagnostic strategies being further refined. We observed a Caucasian adult with clinical and radiographic features of achondroplasia, with no common pathogenic variant. Exome sequencing detected an FGFR3(NM_000142.4):c.1075+95C>G heterozygous intronic variation. In vitro studies showed that this variant results in the aberrant exonization of a 90-nucleotide 5' segment of intron 8, resulting in the substitution of the alanine (Ala359) for a glycine (Gly) and the in-frame insertion of 30 amino acids. This change may alter FGFR3's function. Our report provides the first clinical description of an adult carrying this variant, which completes the phenotype description previously provided in children and confirms the recurrence, the autosomal-dominant pathogenicity, and the diagnostic relevance of this FGFR3 intronic variant. We support its inclusion in routinely used diagnostic tests for osteochondrodysplasia. This may increase the detection rate of causal variants and therefore could have a positive impact on patient management. Finally, FGFR3 alteration via non-coding sequence exonization should be considered a recurrent disease mechanism to be taken into account for new drug design and clinical trial strategies.

A mesomelic skeletal dysplasia, Kantaputra-like, not related to HOXD cluster region, and with phenotypic gender differences

Mesomelic skeletal dysplasia is a heterogeneous group of skeletal disorders that has grown since the molecular basis of these conditions is in the process of research and discovery. Here, we report a Brazilian family with eight affected members over three generations with a phenotype similar to mesomelic Kantaputra dysplasia. This family presents marked shortening of the upper limbs with hypotrophy of the lower limbs and clubfeet without synostosis. Array-based CNV analysis and exome sequencing of four family members failed to show any region or gene candidate. Interestingly, males were more severely affected than females in this family, suggesting that gender differences could play a role in the phenotypic expressivity of this condition.

Case Report: Stüve-Wiedemann syndrome-a rare cause of persistent pulmonary hypertension of the newborn

Introduction

Persistent pulmonary hypertension of the newborn (PPHN) is a life-threatening condition characterized by hypoxemia due to elevated pulmonary vascular resistance. PPHN commonly arises secondary to various underlying conditions, including infection, meconium aspiration, and respiratory distress syndrome. Management includes pulmonary vasodilators, mechanical ventilation, oxygen supplementation, vasopressors, and volume replacement. Stüve-Wiedemann syndrome (SWS), a rare genetic disorder characterized by bone dysplasia, respiratory distress, hyperthermia, and swallowing difficulties, may present with pulmonary hypertension, indicating a poor prognosis.

Case description

A term female neonate presented with secondary respiratory failure and severe PPHN of unknown etiology on the second day of life, necessitating intubation. Clinical findings included facial dysmorphia, camptodactyly, skeletal anomalies, and generalized muscular hypotonia. High-frequency oscillation ventilation and surfactant administration yielded marginal improvement. On the third day of life, a severe pulmonary hypertensive crisis necessitated inhaled and systemic pulmonary vasodilators along with volume and catecholamine therapy. Whole exome sequencing revealed a homozygous mutation in the leukemia inhibitory factor receptor (LIFR) gene, consistent with Stüve-Wiedemann syndrome.

Discussion/conclusion

The case underscores the importance of considering and prompting evaluation of rare genetic causes in the differential diagnosis of PPHN, especially when other abnormalities are present and conventional therapies prove inadequate. Therapeutic strategies must account for the different pathophysiology of primary PPHN including vascular remodeling, as seen in SWS, which may not respond to pulmonary vasodilators typically employed in secondary PPHN due to vasoconstriction. In this case, the patient responded well to treatment for primary PPHN, but the use of high-frequency oscillation ventilation and surfactant was not helpful.

Rare forms of hypomyelination and delayed myelination

Hypomyelination is defined by the evidence of an unchanged pattern of deficient myelination on two MRIs performed at least 6 months apart in a child older than 1 year. When the temporal criteria are not fulfilled, and the follow-up MRI shows a progression of the myelination even if still not adequate for age, hypomyelination is excluded and the pattern is instead consistent with delayed myelination. This can be mild and nonspecific in some cases, while in other cases there is a severe delay that in the first disease stages could be difficult to differentiate from hypomyelination. In hypomyelinating leukodystrophies, hypomyelination is due to a primary impairment of myelin deposition, such as in Pelizaeus Merzabcher disease. Conversely, myelin lack is secondary, often to primary neuronal disorders, in delayed myelination and some condition with hypomyelination. Overall, the group of inherited white matter disorders with abnormal myelination has expanded significantly during the past 20 years. Many of these disorders have only recently been described, for many of them only a few patients have been reported and this contributes to make challenging the diagnostic process and the interpretation of Next Generation Sequencing results. In this chapter, we review the clinical and radiologic features of rare and lesser known forms of hypomyelination and delayed myelination not mentioned in other chapters of this handbook.

[The tooth: A marker of developmental abnormalities]

Tooth formation results from specific epithelial-mesenchymal interactions, which summarize a number of developmental processes. Tooth anomalies may thus reflect subclinical diseases of the kidney, bone and more broadly of the mineral metabolism, skin or nervous system. Odontogenesis starts from the 3rd week of intrauterine life by the odontogenic orientation of epithelial cells by a first PITX2 signal. The second phase is the acquisition of the number, shape, and position of teeth. It depends on multiple transcription and growth factors (BMP, FGF, SHH, WNT). These ecto-mesenchymal interactions guide cell migration, proliferation, apoptosis and differentiation ending in the formation of the specific dental mineralized tissues. Thus, any alteration will have consequences on the tooth structure or shape. Resulting manifestations will have to be considered in the patient phenotype and the multidisciplinary care, but also may contribute to identify the altered genetic circuity.

Management of Combined Fracture Neck of Femur and Femoral Deformity in Osteogenesis Imperfecta Patient: A Case Report

Osteogenesis imperfecta (OI) patients usually sustain repeated fractures from trivial trauma and also have skeletal deformities that affect walking. The bone fragility and repeated fractures produce deformities of the long bones especially in femur and tibia. However, neck of femur (NOF) fractures in OI are rarely described. A 11-year-old male patient known to have OI (Sillence type IV) sustained a NOF fracture after a fall. He also had proximal femoral anterolateral bowing proximally and over an intramedullary (IM) rod inserted 4 years back. He was treated by corrective osteotomy and stabilisation with an IM telescoping nail for the deformed femur and the Wagner technique for the NOF fracture. One year after operation, the patient had recovered satisfactory functional outcome with union of the NOF fracture and correction of the femoral deformity.

Conclusion

The method of the Wagner technique can achieve stable fixation for femoral neck fractures and introduces the least interference with concurrent telescoping nail insertion.

How to cite this article

Elbaseet HM, Ibrahim AH, Abol Oyoun N, et al. Management of Combined Fracture Neck of Femur and Femoral Deformity in Osteogenesis Imperfecta Patient: A Case Report. Strategies Trauma Limb Reconstr 2024;19(1):56-59.

Bronchial obstruction in osteogenesis imperfecta can be detected by forced oscillation technique

Introduction

Respiratory insufficiency is a leading cause of death in individuals with osteogenesis imperfecta (OI). However, evaluating pulmonary function in OI presents challenges. Commonly used pulmonary function tests such as spirometry and body plethysmography are sometimes difficult to perform for OI patients, and reference intervals are not always applicable. The forced oscillation technique (FOT) is a patient-friendly method for detecting respiratory abnormalities that requires no effort from the patient.

Objective

This study investigates the feasibility of FOT in the evaluation of respiratory function in the clinical management of OI patients.

Methods

Twelve OI patients, comprising eight with Sillence OI I, two with OI IV, and two with OI III, underwent spirometry, body plethysmography, and FOT, both pre-and post-administration of salbutamol.

Results

FOT measurements exhibited consistent trends that aligned with spirometry and body plethysmography findings. The resistance at 8 Hz decreased after the administration of salbutamol, indicating that FOT is able to detect bronchial obstruction and its alleviation by medication (p < 0.05). The resonant frequency during expiration was higher than during inspiration in nearly all patients, suggesting obstructive disease. The technique gives insight into both inspiratory and expiratory impairment of pulmonary ventilation. The main FOT parameters showed a relatively high repeatability in duplicate measurements.

Conclusion

Bronchial obstruction can be detected by FOT in patients with OI during quiet breathing, making it an easily executable alternative to other lung function measurements. The technique can detect the bronchodilator effect of sympathomimetic medication. It has the potential to provide information on expiratory flow limitation, pulmonary restriction, and reduced lung compliance.

Clinical features and genetic analysis of a case series of skeletal ciliopathies in a prenatal setting

BACKGROUND

Short-rib polydactyly syndrome (SRPS) refers to a group of lethal skeletal dysplasias that can be difficult to differentiate between subtypes or from other non-lethal skeletal dysplasias such as Ellis-van Creveld syndrome and Jeune syndrome in a prenatal setting. We report the ultrasound and genetic findings of four unrelated fetuses with skeletal dysplasias.

METHODS

Systemic prenatal ultrasound examination was performed in the second or third trimester. Genetic tests including GTG-banding, single nucleotide polymorphism (SNP) array and exome sequencing were performed with amniocytes or aborted fetal tissues.

RESULTS

The major and common ultrasound anomalies for the four unrelated fetuses included short long bones of the limbs and narrow thorax. No chromosomal abnormalities and pathogenic copy number variations were detected. Exome sequencing revealed three novel variants in the DYNC2H1 gene, namely NM_001080463.2:c.6809G > A p.(Arg2270Gln), NM_001080463.2:3133C > T p.(Gln1045Ter), and NM_001080463.2:c.337C > T p.(Arg113Trp); one novel variant in the IFT172 gene, NM_015662.3:4540-5 T > A; and one novel variant in the WDR19 gene, NM_025132.4:c.2596G > C p.(Gly866Arg). The genotypes of DYNC2H1, IFT172 and WDR19 and the phenotypes of the fetuses give hints for the diagnosis of short-rib thoracic dysplasia (SRTD) with or without polydactyly 3, 10, and 5, respectively.

CONCLUSION

Our findings expand the mutation spectrum of DYNC2H1, IFT172 and WDR19 associated with skeletal ciliopathies, and provide useful information for prenatal diagnosis and genetic counseling on rare skeletal disorders.

Tensile Mechanical Properties of Dry Cortical Bone Extracellular Matrix: A Comparison Among Two Osteogenesis Imperfecta and One Healthy Control Iliac Crest Biopsies

Osteogenesis imperfecta (OI) is a genetic, collagen-related bone disease that increases the incidence of bone fractures. Still, the origin of this brittle mechanical behavior remains unclear. The extracellular matrix (ECM) of OI bone exhibits a higher degree of bone mineralization (DBM), whereas compressive mechanical properties at the ECM level do not appear to be inferior to healthy bone. However, it is unknown if collagen defects alter ECM tensile properties. This study aims to quantify the tensile properties of healthy and OI bone ECM. In three transiliac biopsies (healthy n = 1, OI type I n = 1, OI type III n = 1), 23 microtensile specimens (gauge dimensions 10 × 5 × 2 μm3) were manufactured and loaded quasi-statically under tension in vacuum condition. The resulting loading modulus and ultimate strength were extracted. Interestingly, tensile properties in OI bone ECM were not inferior compared to controls. All specimens revealed a brittle failure behavior. Fracture surfaces were graded according to their mineralized collagen fibers (MCF) orientation into axial, mixed, and transversal fracture surface types (FST). Furthermore, tissue mineral density (TMD) of the biopsy cortices was extracted from micro-computed tomogra[hy (μCT) images. Both FST and TMD are significant factors to predict loading modulus and ultimate strength with an adjusted R 2 of 0.556 (p = 2.65e-05) and 0.46 (p = 2.2e-04), respectively. The influence of MCF orientation and DBM on the mechanical properties of the neighboring ECM was further verified with quantitative polarized Raman spectroscopy (qPRS) and site-matched nanoindentation. MCF orientation and DBM were extracted from the qPRS spectrum, and a second mechanical model was developed to predict the indentation modulus with MCF orientation and DBM (R 2 = 67.4%, p = 7.73e-07). The tensile mechanical properties of the cortical bone ECM of two OI iliac crest biopsies are not lower than the one from a healthy and are primarily dependent on MCF orientation and DBM. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

In Vivo Assessment of Skin Surface Pattern: Exploring Its Potential as an Indicator of Bone Biomechanical Properties

The mechanical properties of bone tissue are the result of a complex process involving collagen-crystal interactions. The mineral density of the bone tissue is correlated with bone strength, whereas the characteristics of collagen are often associated with the ductility and toughness of the bone. From a clinical perspective, bone mineral density alone does not satisfactorily explain skeletal fragility. However, reliable in vivo markers of collagen quality that can be easily used in clinical practice are not available. Hence, the objective of the present study is to examine the relationship between skin surface morphology and changes in the mechanical properties of the bone. An experimental study was conducted on healthy children (n = 11), children with osteogenesis imperfecta (n = 13), and women over 60 years of age (n = 22). For each patient, the skin characteristic length (SCL) of the forearm skin surface was measured. The SCL quantifies the geometric patterns formed by wrinkles on the skin's surface, both in terms of size and elongation. The greater the SCL, the more deficient was the organic collagen matrix. In addition, the bone volume fraction and mechanical properties of the explanted femoral head were determined for the elderly female group. The mean SCL values of the healthy children group were significantly lower than those of the elderly women and osteogenesis imperfecta groups. For the aged women group, no significant differences were indicated in the elastic mechanical parameters, whereas bone toughness and ductility decreased significantly as the SCL increased. In conclusion, in bone collagen pathology or bone aging, the SCL is significantly impaired. This in vivo skin surface parameter can be a non-invasive tool to improve the estimation of bone matrix quality and to identify subjects at high risk of bone fracture.

Specific heterozygous variants in MGP lead to endoplasmic reticulum stress and cause spondyloepiphyseal dysplasia

Matrix Gla protein (MGP) is a vitamin K-dependent post-translationally modified protein, highly expressed in vascular and cartilaginous tissues. It is a potent inhibitor of extracellular matrix mineralization. Biallelic loss-of-function variants in the MGP gene cause Keutel syndrome, an autosomal recessive disorder characterized by widespread calcification of various cartilaginous tissues and skeletal and vascular anomalies. In this study, we report four individuals from two unrelated families with two heterozygous variants in MGP, both altering the cysteine 19 residue to phenylalanine or tyrosine. These individuals present with a spondyloepiphyseal skeletal dysplasia characterized by short stature with a short trunk, diffuse platyspondyly, midface retrusion, progressive epiphyseal anomalies and brachytelephalangism. We investigated the cellular and molecular effects of one of the heterozygous deleterious variants (C19F) using both cell and genetically modified mouse models. Heterozygous 'knock-in' mice expressing C19F MGP recapitulate most of the skeletal anomalies observed in the affected individuals. Our results suggest that the main underlying mechanism leading to the observed skeletal dysplasia is endoplasmic reticulum stress-induced apoptosis of the growth plate chondrocytes. Overall, our findings support that heterozygous variants in MGP altering the Cys19 residue cause autosomal dominant spondyloepiphyseal dysplasia, a condition distinct from Keutel syndrome both clinically and molecularly.

Case Report: A prenatal diagnosis of osteogenesis imperfecta in a patient with a novel pathogenic variant in COL1A2

Osteogenesis imperfecta is considered a rare genetic condition which is characterized by bone fragility. In 85% of cases, it is caused by mutations in COL1A1 and COL1A2 genes which are essential to produce type I collagen. We report the case of a female neonate delivered to a 27-year-old women at San Bartolomé Teaching Hospital with a family history of clavicle fracture. A prenatal control with ultrasound was performed to the mother at 29 weeks. A fetus with altered morphology and multiple fractures was found. Therefore, a prenatal diagnosis of osteogenesis imperfecta was performed. The neonate was born with a respiratory distress syndrome and an acyanotic congenital heart disease. Therefore, she remained in NICU until her death. We highlight the importance of prenatal diagnosis, genetic counseling and a multidisciplinary evaluation in this type of pathologies and report a new probably pathogenic variant in the COL1A2 gene detected by exomic sequencing in amniotic fluid.

Genetic testing and diagnostic strategies of fetal skeletal dysplasia: a preliminary study in Wuhan, China

BACKGROUND

Fetal skeletal dysplasia is a diverse group of degenerative diseases of bone and cartilage disorders that can lead to movement disorder and even death. This study aims to evaluate the diagnostic yield of sonographic examination and genetic testing for fetal skeletal dysplasia.

METHODS

From September 2015 to April 2021, the study investigated 24 cases with suspected short-limb fetuses, which were obtained from Tongji Hospital affiliated to Tongji Medical College of Huazhong University of Science and Technology. To identify the causative gene, multiple approaches (including karyotype analysis, copy number variations and whole exome sequencing) were performed on these fetuses. And further segregation analysis of the candidate variant was performed in parents by using Sanger sequencing.

RESULTS

① Out of 24 cases, likely pathogenic variants in FGFR3, FBN2, COL1A2, CUL7 and DYNC2H1 were detected in 6 cases; pathogenic variants in FGFR3, IMPAD1 and GORAB were identified in other 6 cases; and variants in WNT1, FBN1, OBSL1, COL1A1, DYNC2H1 and NEK1, known as Variant of Undetermined Significance, were found in 4 cases. There were no variants detected in the rest 8 cases by the whole exome sequencing. ② Of 24 cases, 12 (50%) were found to carry variants (pathogenic or likely pathogenic) in seven genes with 12 variants. Four fetuses (16.7%) had variants of uncertain significance.

CONCLUSION

Genetic testing combining with ultrasound scanning enhances the accurate diagnosis of fatal skeletal dysplasia in utero, and then provides appropriate genetic counseling.