Hajdu--Cheney syndrome: evolution of phenotype and clinical problems

Orofacial characteristics in a child with Hajdu-Cheney syndrome

Hajdu-Cheney syndrome (HCS) also known as Cranio-skeletal dysplasia is a rare genetic disorder of bone metabolism. It is mainly characterized by acro-osteolysis and generalized osteoporosis. The other distinctive features include a dysmorphic face, short stature, aplasia of facial sinuses, and persistent cranial sutures. Although the condition begins to manifest since birth, the characteristic features become more prominent with age. This syndrome is usually recognized by dentists due to these craniofacial abnormalities. This case report aims to highlight a case of 6-year-old girl HCS who presented with aberrant facial features, premature exfoliation of teeth, unusual mobility of teeth and atypical root resorption in primary dentition.

Hajdu-Cheney syndrome with a novel variant in NOTCH2 gene: A case report

Introduction

Hajdu-Cheney syndrome is a rare disorder caused by truncation mutations in exon 34 of the NOTCH2 gene. The main presentation includes acro-osteolysis, osteoporosis, and dysmorphism. This syndrome affects the other body systems as well.

Case presentation

We report a case of a 6-year-old female that initially developed polyhydramnios and short upper limbs as a fetus. In addition, the patient had multiple anomalies as a neonate, including dysmorphism, congenital heart disease, hearing loss, recurrent respiratory tract infections, skeletal abnormalities, renal cysts, and hypertension. She continues to receive multidisciplinary care, and the finding of a C.7021C > T: P.Q2341x mutation in exon 34 of the NOTCH2 gene confirms the diagnosis. To our knowledge, this is the first case to report this variant in the literature.

Discussion

Because of the rarity of this syndrome and its diverse presentation, a high index of suspicion accompanied by genetic testing is paramount for diagnosing Hajdu-Cheney syndrome. We recommend a multidisciplinary approach for these patients to provide the highest possible quality of care.

Fracture healing in a mouse model of Hajdu-Cheney-Syndrome with high turnover osteopenia results in decreased biomechanical stability

Notch signaling regulates cell fate in multiple tissues including the skeleton. Hajdu-Cheney-Syndrome (HCS), caused by gain-of-function mutations in the Notch2 gene, is a rare inherited disease featuring early-onset osteoporosis and increased risk for fractures and non-union. As the impact of Notch2 overactivation on fracture healing is unknown, we studied bone regeneration in mice harboring a human HCS mutation. HCS mice, displaying high turnover osteopenia in the non-fractured skeleton, exhibited only minor morphologic alterations in the progression of bone regeneration, evidenced by static radiological and histological outcome measurements. Histomorphometry showed increased osteoclast parameters in the callus of HCS mice, which was accompanied by an increased expression of osteoclast and osteoblast markers. These observations were accompanied by inferior biomechanical stability of healed femora in HCS mice. Together, our data demonstrate that structural indices of bone regeneration are normal in HCS mice, which, however, exhibit signs of increased callus turnover and display impaired biomechanical stability of healed fractures.

A case of safe airway management by fiber-optic nasotracheal intubation in general anesthesia in a pediatric patient with Hajdu-Cheney syndrome: a case report

BACKGROUND

Hajdu-Cheney syndrome (HCS) is an extremely rare disorder characterized by progressive acro-osteolysis. A unique facial structure and deformity of the cervical spine are associated with a difficult airway. Although several reports describe general anesthesia with orotracheal intubation for patients with HCS, there have been no reports of nasotracheal intubation with a risk of skull base fracture. We describe nasotracheal intubation for oral surgery in a patient with HCS.

CASE PRESENTATION

A 13-year-old girl with HCS was scheduled for dental surgery. Preoperative computed tomography revealed no abnormalities including fractures in the skull base or cervical spine. After confirming a lack of vocal cord paralysis by bronchofiberscopic inspection from the nose, general anesthesia was induced with sevoflurane, remifentanil, and rocuronium. Fiber-optic nasotracheal intubation was successfully performed without complications such as depletion of oxygen saturation and massive epistaxis, and the surgery was completed uneventfully. She was discharged the day after surgery with no anesthesia-related complications.

CONCLUSIONS

We were able to safely manage the airway of a patient with HCS by nasotracheal intubation under general anesthesia.

Acro-osteolysis: imaging, differential diagnosis, and disposition review

Acro-osteolysis is the osseous destruction of the hand or foot distal phalanges. The categories of the disease include terminal tuft, midshaft, or mixed types. Recognition of acro-osteolysis is straightforward on radiographs, but providing an accurate differential diagnosis and appropriately recommending advanced imaging or invasive tissue diagnosis can be more elusive. A radiologist's ability to provide advanced assessment can greatly aid clinicians in expedient diagnosis and management of the array of diseases presenting with acro-osteolysis.

Progress and Current Status in Hajdu-Cheney Syndrome with Focus on Novel Genetic Research

Hajdu-Cheney syndrome (HCS) is a rare autosomal dominant manifestation of a congenital genetic disorder caused by a mutation in the NOTCH2 gene. NOTCH signaling has variations from NOTCH 1 to 4 and maintains homeostasis by determining and regulating the proliferation and differentiation of various cells. In HCS, the over-accumulated NOTCH2 causes abnormal bone resorption due to its continuous excessive signaling. HCS is characterized by progressive bone destruction, has complex wide-range clinical manifestations, and significantly impacts the patient’s quality of life. However, no effective treatment has been established for HCS to date. There are genetic variants of NOTCH2 that have been reported in the ClinVar database of the U.S. National Institutes of Health. In total, 26 mutant variants were detected based on the American College of Medical Genetics and Genomics (ACMC). To date, there has been no comprehensive compilation of HCS mutations. In this review, we provide the most comprehensive list possible of HCS variants, nucleotide changes, amino acid definitions, and molecular consequences reported to date, following the ACMC guidelines.

Hajdu-Cheney Syndrome: A Novel NOTCH2 Mutation in a Spanish Child in Treatment with Vibrotherapy: A Case Report

A case report of an 11-year-old boy with a de novo variant in NOTCH2 and clinical features characteristic of Hajdu-Cheney syndrome is reported, with acroosteolysis of the distal phalanges of the feet and hands, generalized osteoporosis, musculoskeletal and craniofacial alterations, short stature, bowing of long bones, vertebral anomalies, genu recurvatum, hypertrichosis, joint and skin hyperlaxity, atopic dermatitis, megalocorneas, micrognathia and frequent respiratory infections, among others. Treatment is with bisphosphonates in the framework of bone density improvement and with focal vibration therapy for rehabilitation of the musculoskeletal system and gait improvement. The three generalities of this pathology-phenotypic variability, degenerative character and the presence of generalized osteoporosis and acroosteolysis of the distal phalanges-are seen in this case, whose diagnostic confirmation was made by genetic study.

Nursing Care Plan for Patients with Hajdu-Cheney Syndrome

Hajdu-Cheney syndrome is a rare genetic disease. Its main features include phenotypic variability, age-dependent progression and the presence of acroosteolysis of the distal phalanges and generalized osteoporosis, which have significant disabling potential. Currently, there is no effective curative treatment, so nursing care is essential to ensure the maintenance of the quality of life of these patients. The main objective of this study was to establish a specific standardized nursing care plan using the NANDA-NIC-NOC taxonomy. The application of a care plan as such would improve the quality of life of patients affected by this rare disease, will contribute to increasing healthcare professionals' knowledge on this matter and will support future studies on this disease.

Hajdu-Cheney Syndrome: Report of a Case in Spain

This paper describes the case of a 54-year-old woman diagnosed with Hajdu–Cheney syndrome, who presents with characteristic craniofacial dysmorphia, short stature, premature loss of teeth, developmental skeletal disorders, fibrocystic mastopathy, bilateral hearing loss and an intermittent mild neutropenia. The patient received treatment with bisphosphonates and was awaiting evaluation for surgical arthroplasty of both hips when she suffered a motor vehicle accident, which led to a rapid progression in her disease by increasing her degree of dependence for most activities of daily living. The clinical presentation and radiologic findings seen in this case confirm the three main features of the syndrome: phenotypic variability, an age-dependent progression and the presence of generalized osteoporosis and acroosteolysis of distal phalanges. The main objective of the manuscript is to describe a new case of a patient diagnosed with Hajdu–Cheney syndrome. Due to the low prevalence of the syndrome and the small number of cases reported in the scientific literature, obtaining a complete description and a global perspective of the disease is complex.

Hajdu Cheney syndrome; A novel NOTCH2 mutation in a Syrian child, and treatment with zolidronic acid: A case report and a literature review of treatments

INTRODUCTION

Hajdu Cheney Syndrome (HCS) is a rare genetic disorder characterized by skeletal deformities such as acroosteolysis, osteoporosis, unique craniofacial features, and other systemic abnormalities. This syndrome is caused by NOTCH2 gene mutations, which cause an increase of osteoclast and osteoblast activity that leads to the increased bone resorption. Because of how rare the syndrome is and the vague onset of the symptoms, it can be challenging to make an early diagnosis.

CASE PRESENTATION

We report a case of a female child with HCS who has a new NOTCH2 mutation sequence; (NM_024408.3:c.6463G > T) protein change (Glu2155*), and to our knowledge this is the first reported and diagnosed case in Syria. She presents with short stature, unique craniofacial features, scoliosis, kyphosis, and signs of osteoporosis, in addition to Patent Ductus Arteriosus. The patient was diagnosed with Hajdu Cheney Syndrome, and administered zolidronic acid, and she responded well to the treatment; showing signs of improved bone density and improvement in height, where her bone density improved from 0.23 to 0.31, and she gained 11 cm in height after the treatment.

CONCLUSION

Due to the rarity of the syndrome, there is no established guideline for treatment yet. Based on the pathophysiology of the syndrome that causes increased bone resorption, treatment with the Bisphosphonates group has yielded positive outcomes. Furthermore, we compare different treatments in the literature with their results.

Operative Management of Spinal Deformity Secondary to Hajdu-Cheney Syndrome

Hajdu-Cheney syndrome (HCS) is an exceedingly rare disease with fewer than 100 cases described in the medical literature. It is most strongly associated with a defect in the transmembrane protein NOTCH2. Though the exact mechanism in humans is not yet known, the defect results in various skeletal abnormalities including severe osteoporosis placing these patients at high risk for progressive spinal deformity. Due to various common syndromic features including ligamentous laxity, increased osteoclast activity, skeletal malformations, patency of cranial sutures, and the aforementioned severe osteoporosis, these patients require special consideration from treating surgeons. There are currently only nine reported cases of spinal surgery in HCS patients. Herein, we describe the cases of two patients with HCS requiring surgery for progressive spinal deformity. Six months following surgery, both patients reported excellent outcomes with significant improvement in symptoms.

Oral Surgery Procedures in a Patient with Hajdu-Cheney Syndrome Treated with Denosumab-A Rare Case Report

Background: Hajdu-Cheney syndrome (HCS) is a very rare autosomal-dominant congenital disease associated with mutations in the NOTCH2 gene. This disorder affects the connective tissue and is characterized by severe bone resorption. Hajdu-Cheney syndrome most frequently affects the head and feet bones (acroosteolysis). Case report: We present an extremely rare case of a 34-year-old male with Hajdu-Cheney syndrome. The patient was admitted to the Department of Oral Surgery, Medical University of Gdańsk, in order to perform the extraction of three teeth. These teeth were not eligible for conservative treatment and prosthetic reconstruction. The patient was treated with denosumab (angiogenesis and receptor activator of nuclear factor-κB RANK ligand inhibitor, RANKL). Discussion: Denosumab is a monoclonal antibody against RANKL. This drug works through a suppression of osteoclast activity. In cases of patients in which the pathway of the RANK/RANKL/osteoprotegerin is dysregulated, denosumab has been approved for the treatment off-label. In patients receiving denosumab, a delayed wound healing in the oral cavity and osteonecrosis may occur. Dental procedures involving the alveolar bone process (tooth extractions and bone alveoloplasty) may be a risk factor for medication-related osteonecrosis of the jaw (MRONJ). Spontaneous osteonecrosis is rarely observed. MRONJ consists of the destruction of exposed bone, with the exposure persisting for a minimum of 6–8 weeks. This is the first article about an HCS patient treated with denosumab who underwent invasive oral surgery procedures. This case report highlights the difficulties for professionals occurring during the oral surgery procedures in such patients.

Hajdu Cheney Syndrome due to NOTCH2 defect - First case report from Pakistan and review of literature

INTRODUCTION AND IMPORTANCE

Hajdu Cheney Syndrome (HCS) is a rare skeletal disease characterized by severe, progressive focal bone loss with osteoporosis, variable craniofacial, vertebral anomalies and distinctive facial features. It is inherited as an autosomal dominant disease although sporadic cases have been described in literature. Identifying these cases in clinical practice is important for proper diagnosis and management.

CASE PRESENTATION

We report a case of a 36-year-old male patient presented at metabolic bone disease clinic at the Aga Khan University Hospital with history of multiple fragility fractures and juvenile osteoporosis since childhood. DNA sequence analysis of the NOTCH2 coding sequence revealed a pathogenic variant in NOTCH 2, Exon 34, c.6426_6427insTT (p.Glu2143Leufs*5), consistent with a NOTCH2 related conditions including HCS.

CLINICAL DISCUSSION

The multitude of presentations associated with HCS are linked to the NOTCH2 gene, as Notch signaling is one of the core signaling pathways that control embryonic development. Hence, mutations in the Notch signaling pathway cause developmental phenotypes that affect various organs including the liver, skeleton, heart, eye, face, kidney, and vasculature.

CONCLUSION

To the best of our knowledge, nucleotide mutations of c.6933delT, c.6854delA, c.6787C.T, and c.6424-6427delTCTG were all determined to be novel, with c.6428T > C being the most common mutation found in literature. The c.6426_6427insTT mutation our patient was found to have via gene sequencing too appears to be a novel mutation, which has not previously been reported in literature.

Hand Deformities in Hajdu-Cheney Syndrome: A Case Series of 3 Patients Across 3 Consecutive Generations

Hajdu-Cheney syndrome is a rare condition characterized by acro-osteolysis, osteoporosis, and multiple craniofacial anomalies. The goal of treatment is to reduce the associated symptoms and to prevent osteoporotic fractures. This is a report of 3 patients across consecutive generations demonstrating variable phenotypic severity. The hand surgeon was the first medical care provider visited by the patients because of the shortening of the fingers.

Notch and the regulation of osteoclast differentiation and function

Notch 1 through 4 are transmembrane receptors that play a pivotal role in cell differentiation and function; this review addresses the role of Notch signaling in osteoclastogenesis and bone resorption. Notch receptors are activated following interactions with their ligands of the Jagged and Delta-like families. In the skeleton, Notch signaling controls osteoclast differentiation and bone-resorbing activity either directly acting on osteoclast precursors, or indirectly acting on cells of the osteoblast lineage and cells of the immune system. NOTCH1 inhibits osteoclastogenesis, whereas NOTCH2 enhances osteoclast differentiation and function by direct and indirect mechanisms. NOTCH3 induces the expression of RANKL in osteoblasts and osteocytes and as a result induces osteoclast differentiation. There is limited expression of NOTCH4 in skeletal cells. Selected congenital disorders and skeletal malignancies are associated with dysregulated Notch signaling and enhanced bone resorption. In conclusion, Notch signaling is a critical pathway that controls osteoblast and osteoclast differentiation and function and regulates skeletal homeostasis in health and disease.

Hajdu-Cheney Syndrome: A Systematic Review of the Literature

Hajdu–Cheney syndrome (HCS) is a rare genetic disease that causes acroosteolysis and generalized osteoporosis, accompanied by a series of developmental skeletal disorders and multiple clinical and radiological manifestations. It has an autosomal dominant inheritance, although there are several sporadic non-hereditary cases. The gene that has been associated with Hajdu-Cheney syndrome is NOTCH2. The described phenotype and clinical signs and symptoms are many, varied, and evolve over time. As few as 50 cases of this disease, for which there is currently no curative treatment, have been reported to date. The main objective of this systematic review was to evaluate the results obtained in research regarding Hajdu–Cheney Syndrome. The findings are reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines and were registered on the web PROSPERO under the registration number CRD42020164377. A bibliographic search was carried out using the online databases Orphanet, PubMed, and Scielo; articles from other open access sources were also considered. Finally, 76 articles were included, and after their analysis, we have obtained a series of hypotheses as results that will support further studies on this matter.

Obstructive hydrocephalus treated with endoscopic third ventriculostomy in a patient with Hajdu-Cheney syndrome: case report

Hajdu-Cheney syndrome (HCS) is a rare genetic disorder with autosomal dominant inheritance, although most cases result from de novo mutations. Progressive platybasia and basilar impression (BI) can potentiate obstructive hydrocephalus due to aqueductal stenosis. Limited literature exists on the surgical intervention for hydrocephalus in patients with this condition. The authors present (to their knowledge) the first case of obstructive hydrocephalus due to aqueductal stenosis from BI treated with an endoscopic third ventriculostomy in a patient with the complex anatomy of HCS.

Notch Signaling in Kidney Development, Maintenance, and Disease

Kidney development involves formation of nephrons intricately aligned with the vasculature and connected to a branched network of collecting ducts. Notch signaling plays multiple roles during kidney development involving the formation of nephrons composed of diverse epithelial cell types arranged into tubular segments, all the while maintaining a nephron progenitor niche. Here, we review the roles of Notch signaling identified from rodent kidney development and injury studies, while discussing human kidney diseases associated with aberrant Notch signaling. We also review Notch signaling requirement in maintenance of mature kidney epithelial cell states and speculate that Notch activity regulation mediates certain renal physiologic adaptations.

Phenotypic presentations of Hajdu-Cheney syndrome according to age - 5 distinct clinical presentations

We present five Danish individuals with Hajdu-Cheney syndrome (HJCYS) (OMIM #102500), a rare multisystem skeletal disorder with distinctive facies, generalised osteoporosis and progressive focal bone destruction. In four cases positive genetic screening of exon 34 of NOTCH2 supported the clinical diagnosis; in one of these cases, mosaicism was demonstrated, which, to our knowledge, has not previously been reported. In one case no genetic testing was performed since the phenotype was definite, and the diagnosis in the mother was genetically confirmed. The age of the patients differs widely from ten to 57 years, allowing a natural history description of the phenotype associated with this ultra-rare condition. The evolution of the condition is most apparent in the incremental bone loss leading to osteoporosis and the acro-osteolysis, both of which contribute significantly to disease burden.

Congenital Glaucoma: a Novel Ocular Manifestation of Hajdu-Cheney Syndrome

Hajdu-Cheney Syndrome (HSC) is a rare multisystem disease in which the phenotype involves acro-osteolysis, severe osteoporosis, short stature, wormian bones, facial dysmorphism, central neurological abnormalities, cardiovascular defects, and polycystic kidneys. We describe an infant with severe manifestations of HCS in whom congenital glaucoma was a significant early feature, which has not been reported to date. HCS cases reported to date have involved truncating mutations in exon 34 of NOTCH2 upstream the PEST domain that lead to the development of a truncated and stable NOTCH2 protein which upregluates notch signaling. We describe a hitherto undescribed missense mutation that is predicted to be pathogenic, with functional characterization remaining to be performed. Serpentine fibula-polycystic kidney syndrome (SFPKS) is allelic to HCS and commonly associated with missense NOTCH2 mutations. Our patient provides new ophthalmological manifestations of HCS and provides insight into the potential role of notch signaling in the anterior chamber development.

A 23-year follow-up of a male with Hajdu-Cheney syndrome due to NOTCH2 mutation

We present a natural history of a 32-year-old man with Hajdu-Cheney syndrome (HJCYS), because of the de novo truncating mutation in the exon 34 of NOTCH2 (c.6424-6427delTCTG, p.Ser2142ArgfsX4), who has been followed up for a period of 23 years (between 9 and 32 years). During follow-up, we observed abnormalities of vision, hearing, voice, and progression of craniofacial features in the form of skeletal dysplasia with affected skull, dentition, spine, limbs, fingers, and toes. Low bone mineral density and history of fragility fractures also suggested primary osteoporosis being a clinical manifestation. According to Stengel-Rutkowski, Schimanek, and Wernheimer (1984; Human Genetics, 6, 272-295), systematic data acquisition has been used for quantitative analysis of anthropological, radiographic, and clinical features at childhood, adolescence, and young adulthood separately. A detailed phenotype description together with the results of reanalysis of 14 reports so far published on patients with HJCYS and NOTCH2 mutation showed similar phenotype evolution with age. The spectrum of observed features may improve diagnostic tools for HJCYS at different periods of the lifespan.

Bisphosphonate therapy for spinal osteoporosis in Hajdu-Cheney syndrome - new data and literature review

Background

Hajdu-Cheney syndrome (HCS) (#OMIM 102500) is a rare, autosomal dominant condition that presents in early childhood. It is caused by mutations in the terminal exon of NOTCH2, which encodes the transmembrane NOTCH2 receptor. This pathway is involved in the coupled processes of bone formation and resorption. The skeletal features of HCS include acro-osteolysis of the digits and osteoporosis commonly affecting vertebrae and long bones. Fractures are a prominent feature and are associated with significant morbidity. There is no specific treatment, but with both acro-osteolysis and generalized osteoporosis, it is possible that anti-resorptive treatment might be of benefit. However, to date only a few case reports have evaluated the effectiveness of bisphosphonate treatment.

Methods

We describe the clinical features, treatment regimens and response to bisphosphonate treatment in 7 newly described patients aged 6–39 with HCS, and pooled the data with that from 8 previously published cases (a total of 17 courses of treatment in 15 individuals).

Results

The mean lumbar spine bone mineral density (BMD) z-score before treatment was − 2.9 (SD 1.2). In 14 courses of treatment (82%), there was an increase in BMD with bisphosphonate treatment, but the impact (in terms of change in spinal BMD z-score) appeared to be less with advancing age (p = 0.01). There was no evidence that acro-osteolysis was prevented.

Conclusions

Although individual response is variable and age-related, the data support a role for bisphosphonates in preventing or treating spinal osteoporosis in HCS, but bone loss from the lumbar spine may be rapid after cessation.

Notch signaling: its roles and therapeutic potential in hematological malignancies

Notch is a highly conserved signaling system that allows neighboring cells to communicate, thereby controlling their differentiation, proliferation and apoptosis, with the outcome of its activation being highly dependent on signal strength and cell type. As such, there is growing evidence that disturbances in physiological Notch signaling contribute to cancer development and growth through various mechanisms. Notch was first reported to contribute to tumorigenesis in the early 90s, through identification of the involvement of the Notch1 gene in the chromosomal translocation t(7;9)(q34;q34.3), found in a small subset of T-cell acute lymphoblastic leukemia. Since then, Notch mutations and aberrant Notch signaling have been reported in numerous other precursor and mature hematological malignancies, of both myeloid and lymphoid origin, as well as many epithelial tumor types. Of note, Notch has been reported to have both oncogenic and tumor suppressor roles, dependent on the cancer cell type. In this review, we will first give a general description of the Notch signaling pathway, and its physiologic role in hematopoiesis. Next, we will review the role of aberrant Notch signaling in several hematological malignancies. Finally, we will discuss current and potential future therapeutic approaches targeting this pathway.

High Bone Turnover in Mice Carrying a Pathogenic Notch2 Mutation Causing Hajdu-Cheney Syndrome

Hajdu-Cheney syndrome (HCS) is a rare autosomal-dominant disorder primarily characterized by acro-osteolysis and early-onset osteoporosis. Genetically, HCS is caused by nonsense or deletion mutations within exon 34 of the NOTCH2 gene, resulting in premature translational termination and production of C-terminally truncated NOTCH2 proteins that are predicted to activate NOTCH2-dependent signaling. To understand the role of Notch2 in bone remodeling, we developed a mouse model of HCS by introducing a pathogenic mutation (6272delT) into the murine Notch2 gene. By μCT and undecalcified histology, we observed generalized osteopenia in two independent mouse lines derived by injection of different targeted embryonic stem (ES) cell clones, yet acro-osteolysis did not occur until the age of 52 weeks. Cellular and dynamic histomorphometry revealed a high bone turnover situation in Notch2^+/HCS mice, since osteoblast and osteoclast indices were significantly increased compared with wild-type littermates. Whereas ex vivo cultures failed to uncover cell-autonomous gain-of-functions within the osteoclast or osteoblast lineage, an unbiased RNA sequencing approach identified Tnfsf11 and Il6 as Notch-signaling target genes in bone marrow cells cultured under osteogenic conditions. Because we further observed that the high-turnover pathology of Notch2^+/HCS mice was fully normalized by alendronate treatment, our results demonstrate that mutational activation of Notch2 does not directly control osteoblast activity but favors a pro-osteoclastic gene expression pattern, which in turn triggers high bone turnover. © 2017 American Society for Bone and Mineral Research.

Foot Deformities in Hajdu-Cheney Syndrome: A Rare Case Report and Review of the Literature

Introduction:

Hajdu-Cheney syndrome (HCS) is a rare autosomal dominant disease characterized by acroosteolysis, wormian skull bones with persistent skull sutures, premature loss of teeth, micrognathia, short stature, hypermobility of the joints, neurologic manifestations such as basilar invagination with subsequent paresthesia, hearing loss, and speech alterations, and osteoporosis with tendency to pathologic fractures of long bones and vertebrae as well as painful hands and feet. Very few cases have been earlier reported in the literature.

Case Report:

We report a case of a 50-year-old female with bilateral foot deformities as a manifestation of the rare genetic disorder HCS. Surgical management of the left foot consisted of Morton’s neuroma excision and Weil osteotomy with proximal interphalangeal joint resection and Kirschner wire fixation of the second and third metatarsophalangeal (MTP) joints. Recurrent subluxation of the left second MTP joint was observed at 5-week follow-up. The right foot was treated similarly 7weeks after the initial operation. The post-operative course of the right foot was complicated by bone resorption and nonunion of the second and third metatarsal Weil osteotomies.

Conclusion:

Management of complex foot deformities associated with HCS can be challenging and have not previously been described in the literature. Underlying bone and connective tissue abnormalities intrinsic to the syndrome may increase the risk of recurrence after surgical correction. Consideration should be given to such post-operative complications when treating foot deformities in a patient with HCS.

NOTCH2 Hajdu-Cheney Mutations Escape SCFFBW7-Dependent Proteolysis to Promote Osteoporosis

Hajdu-Cheney syndrome (HCS), a rare autosomal disorder caused by heterozygous mutations in NOTCH2, is clinically characterized by acro-osteolysis, severe osteoporosis, short stature, neurological symptoms, cardiovascular defects, and polycystic kidneys. Recent studies identified that aberrant NOTCH2 signaling and consequent osteoclast hyperactivity are closely associated with the bone-related disorder pathogenesis, but the exact molecular mechanisms remain unclear. Here, we demonstrate that sustained osteoclast activity is largely due to accumulation of NOTCH2 carrying a truncated C terminus that escapes FBW7-mediated ubiquitination and degradation. Mice with osteoclast-specific Fbw7 ablation revealed osteoporotic phenotypes reminiscent of HCS, due to elevated Notch2 signaling. Importantly, administration of Notch inhibitors in Fbw7 conditional knockout mice alleviated progressive bone resorption. These findings highlight the molecular basis of HCS pathogenesis and provide clinical insights into potential targeted therapeutic strategies for skeletal disorders associated with the aberrant FBW7/NOTCH2 pathway as observed in patients with HCS.

Extreme proximal junctional kyphosis-a complication of delayed lambdoid suture closure in Hajdu-Cheney syndrome: a case report and literature review

PURPOSE

To describe the manifestations, surgical treatment, and potential complications of Hajdu-Cheney syndrome (HCS), and the management of these complications.

METHODS

The clinical presentation, management and outcome of HCS with severe osteoporosis and open skull sutures is presented, together with a literature review.

RESULTS

A 20-year-old female with HCS underwent posterior occipitocervical fusion for symptoms of progressive basilar invagination. Because of delayed lambdoid suture closure, the stiff fusion construct lead to increased suture distraction, most notably in the upright (suture-open) position, with relief in the supine (suture-closed) position. This was successfully remedied with extension of the fusion construct anteriorly over the skull vertex to the frontal bones.

CONCLUSIONS

In patients with HCS and other conditions with delayed suture closure, the surgeon must be cognizant of the presence of mobility at the suture lines, and consider extending the fusion construct anteriorly over the skull vertex up to the frontal bones. Because of significant osteoporosis in these syndromes, multiple fixation points and augmentation with bone graft are important principles.

Bone Structural Characteristics and Response to Bisphosphonate Treatment in Children With Hajdu-Cheney Syndrome

CONTEXT

Hajdu-Cheney syndrome (HJCYS) is a rare, multisystem bone disease caused by heterozygous mutations in the NOTCH2 gene. Histomorphometric and bone ultrastructural analyses in children have not been reported and sparse evidence exists on response to bisphosphonate (BP) therapy.

OBJECTIVE

To investigate clinical and bone histomorphometric characteristics, bone matrix mineralization, and the response of bone geometry and density to BP therapy.

PATIENTS

Five children with HJCYS (three males) between 6.7 and 15.3 years of age.

INTERVENTIONS

Various BP regimens (pamidronate, zoledronic acid, and alendronate) were used for between 1 and 10 years.

MAIN OUTCOME MEASURES

Pretreatment transiliac bone biopsy specimens and peripheral quantitative computed tomography results were available in four and three subjects, respectively. Bone histomorphometry and quantitative backscattered electron imaging were performed in two patients. The response to BP was monitored using dual-energy X-ray absorptiometry and peripheral quantitative computed tomography.

RESULTS

Three patients had previously unreported NOTCH2 mutations. Histomorphometry demonstrated increased bone resorption and osteoclast numbers, increased heterogeneity of mineralization, and immature, woven bone. Trabecular bone formation was normal or elevated. Radius cortical thickness and density and lumbar spine bone mineral density were reduced at baseline and increased in response to BP therapy, which was not sustained after therapy discontinuation.

CONCLUSIONS

Increased bone resorption and low cortical thickness are consistent with the effect of activating NOTCH2 mutations, which stimulate osteoclastogenesis. The increase in lumbar spine bone density and radial cortical thickness and density by BP therapy provides evidence of beneficial treatment effects in children with HJCYS.

End-Stage Renal Disease in an Infant With Hajdu-Cheney Syndrome

Hajdu-Cheney syndrome (HJCYS) is a rare, autosomal dominant, skeletal disorder caused by mutations in the NOTCH2 signaling pathway for which genetic testing has recently become available. Renal abnormalities are associated in at least 10% of cases. We present an 8-year-old Caucasian boy, born with multiple dysmorphic features consistent with HJCYS. Imaging of the urinary tract revealed bilateral cystic dysplastic kidneys with associated vesicoureteral reflux. Renal function has been impaired since birth and deteriorated progressively to end-stage renal disease (ESRD) by the age of two and a half years, when peritoneal dialysis was initiated and only recently renal transplantation was performed. Additional congenital abnormalities and multisystem involvement in HJCYS further complicated management, and he developed refractory anemia. Molecular diagnosis was confirmed by identification of a truncating mutation in exon 34 of NOTCH2. Although, renal abnormalities are considered an integral part of the HJCYS, published reports on ESRD are scarce. In those few published cases, where ESRD was recognized, renal failure developed either in late adolescence or adulthood. This is the first report of early ESRD occurring in a child. Patients with HJCYS may need chronic renal replacement therapy even in early childhood. The management of these children can be challenging given the multisystemic manifestations of HJCYS.

Neuroimaging Findings in Pediatric Genetic Skeletal Disorders: A Review

Genetic skeletal disorders (GSDs) are a heterogeneous group characterized by an intrinsic abnormality in growth and (re-)modeling of cartilage and bone. A large subgroup of GSDs has additional involvement of other structures/organs beside the skeleton, such as the central nervous system (CNS). CNS abnormalities have an important role in long-term prognosis of children with GSDs and should consequently not be missed. Sensitive and specific identification of CNS lesions while evaluating a child with a GSD requires a detailed knowledge of the possible associated CNS abnormalities. Here, we provide a pattern-recognition approach for neuroimaging findings in GSDs guided by the obvious skeletal manifestations of GSD. In particular, we summarize which CNS findings should be ruled out with each GSD. The diseases (n = 180) are classified based on the skeletal involvement (1. abnormal metaphysis or epiphysis, 2. abnormal size/number of bones, 3. abnormal shape of bones and joints, and 4. abnormal dynamic or structural changes). For each disease, skeletal involvement was defined in accordance with Online Mendelian Inheritance in Man. Morphological CNS involvement has been described based on extensive literature search. Selected examples will be shown based on prevalence of the diseases and significance of the CNS involvement. CNS involvement is common in GSDs. A wide spectrum of morphological abnormalities is associated with GSDs. Early diagnosis of CNS involvement is important in the management of children with GSDs. This pattern-recognition approach aims to assist and guide physicians in the diagnostic work-up of CNS involvement in children with GSDs and their management.

Notch Signaling and the Skeleton

Notch 1 to 4 receptors are important determinants of cell fate and function, and Notch signaling plays an important role in skeletal development and bone remodeling. After direct interactions with ligands of the Jagged and Delta-like families, a series of cleavages release the Notch intracellular domain (NICD), which translocates to the nucleus where it induces transcription of Notch target genes. Classic gene targets of Notch are hairy and enhancer of split (Hes) and Hes-related with YRPW motif (Hey). In cells of the osteoblastic lineage, Notch activation inhibits cell differentiation and causes cancellous bone osteopenia because of impaired bone formation. In osteocytes, Notch1 has distinct effects that result in an inhibition of bone resorption secondary to an induction of osteoprotegerin and suppression of sclerostin with a consequent enhancement of Wnt signaling. Notch1 inhibits, whereas Notch2 enhances, osteoclastogenesis and bone resorption. Congenital disorders of loss- and gain-of-Notch function present with severe clinical manifestations, often affecting the skeleton. Enhanced Notch signaling is associated with osteosarcoma, and Notch can influence the invasive potential of carcinoma of the breast and prostate. Notch signaling can be controlled by the use of inhibitors of Notch activation, small peptides that interfere with the formation of a transcriptional complex, or antibodies to the extracellular domain of specific Notch receptors or to Notch ligands. In conclusion, Notch plays a critical role in skeletal development and homeostasis, and serious skeletal disorders can be attributed to alterations in Notch signaling.

Capillaroscopic findings in a case of Hajdu-Cheney syndrome

Hajdu-Cheney syndrome (HCS) is a rare disease which causes osteoporosis, digit shortening, and early tooth loss. In a young HCS female patient, the nailfold capillaroscopy showed reduced capillary height and reduced density in all affected fingers. Capillaroscopy could improve follow-up and therapy assessment in HCS. Hajdu-Cheney syndrome (HCS) is a very rare connective tissue disease characterized by osteoporosis, early dentition loss and a particular phenotype as a result of enhanced NOTCH2 signaling. The pathogenesis of bone resorption and osteoporosis is not fully understood. The altered angiogenesis may play a role in acroosteolysis. We performed capillaroscopy in order to assess the microvascular involvement in a 21-year-old female patient with sporadic HCS. The patient presented with severe parodontopathy, acroosteolysis, and clubbing of four fingers and three toes. Hand radiographs showed periarticular osteoporosis and asymmetric bony involvement with acral resorption and/or transversal lucency bands in several fingers. Early collagen-vascular diseases were ruled out by clinical and ancillary examinations, including immunology and immunoblot for systemic sclerosis. Nailfold capillaroscopy showed reduction of capillary height and density in all affected fingers. Notably, in the fingers with acral resorption, many capillaries were dilated, while in the ones with radiolucency band, capillary dilation was a rare finding. In clinically unaffected fingers, the capillaroscopic findings were normal.To our knowledge, this is the first report of capillaroscopic findings in HCS. The nailfold capillaroscopic aspect reflects the involvement of acral vessels in HCS; thus, capillaroscopy may represent an early diagnostic tool as well as a means of therapeutical assessment. Repeated capillaroscopy in HCS may also add to the understanding of its pathogenesis.

Hajdu Cheney Syndrome

Hajdu-Cheney Syndrome is a rare genetic disorder characterised by progressive focal bone destruction. It is known to be an autosomal dominant disorder but there have been reports of sporadic cases as well. Although the disease manifestation is found to begin from birth, it is most often not diagnosed until adolescence or adulthood. It could be due to the rarity of the condition and the variation of the disease manifestation at different age groups. We report a case of Hajdu-Cheney Syndrome in a 26-year-old male who presented with severe periodontitis and premature loss of teeth. The other characteristic features included craniofacial dysmorphism, abnormalities of the digits and dental anomalies. Patients with craniofacial dysmorphism along with dental abnormalities should be thoroughly examined for any underlying systemic disorder. A team of specialists may be able to diagnose this condition before the disease is advanced.

Hajdu-Cheney syndrome: a review

Hajdu Cheney Syndrome (HCS), Orpha 955, is a rare disease characterized by acroosteolysis, severe osteoporosis, short stature, specific craniofacial features, wormian bones, neurological symptoms, cardiovascular defects and polycystic kidneys. HCS is rare and is inherited as autosomal dominant although many sporadic cases have been reported. HCS is associated with mutations in exon 34 of NOTCH2 upstream the PEST domain that lead to the creation of a truncated and stable NOTCH2 protein with enhanced NOTCH2 signaling activity. Although the number of cases with NOTCH2 mutations reported are limited, it would seem that the diagnosis of HCS can be established by sequence analysis of exon 34 of NOTCH2. Notch receptors are single-pass transmembrane proteins that determine cell fate, and play a critical role in skeletal development and homeostasis. Dysregulation of Notch signaling is associated with skeletal developmental disorders. There is limited information about the mechanisms of the bone loss and acroosteolysis in HCS making decisions regarding therapeutic intervention difficult. Bone antiresorptive and anabolic agents have been tried to treat the osteoporosis, but their benefit has not been established. In conclusion, Notch regulates skeletal development and bone remodeling, and gain-of-function mutations of NOTCH2 are associated with HCS.

Platybasia in 22q11.2 deletion syndrome is not correlated with speech resonance

BACKGROUND

An abnormally obtuse cranial base angle, also known as platybasia, is a common finding in patients with 22q11.2 deletion syndrome (22q11DS). Platybasia increases the depth of the velopharynx and is therefore postulated to contribute to velopharyngeal dysfunction. Our objective was to determine the clinical significance of platybasia in 22q11DS by exploring the relationship between cranial base angles and speech resonance.

METHODS

In this retrospective chart review at a tertiary hospital, 24 children (age, 4.0-13.1 years) with 22q11.2DS underwent speech assessments and lateral cephalograms, which allowed for the measurement of the cranial base angles.

RESULTS

One patient (4%) had hyponasal resonance, 8 (33%) had normal resonance, 10 (42%) had hypernasal resonance on vowels only, and 5 (21%) had hypernasal resonance on both vowels and consonants. The mean cranial base angle was 136.5° (standard deviation, 5.3°; range, 122.3-144.8°). The Kruskal-Wallis test showed no significant relationship between the resonance ratings and cranial base angles (P=0.242). Cranial base angles and speech ratings were not correlated (Spearman correlation=0.321, P=0.126). The group with hypernasal resonance had a significantly more obtuse mean cranial base angle (138° vs. 134°, P=0.049) but did not have a greater prevalence of platybasia (73% vs. 56%, P=0.412).

CONCLUSIONS

In this retrospective chart review of patients with 22q11DS, cranial base angles were not correlated with speech resonance. The clinical significance of platybasia remains unknown.

The ever-expanding conundrum of primary osteoporosis: aetiopathogenesis, diagnosis, and treatment

In recent years, as knowledge regarding the etiopathogenetic mechanisms of bone involvement characterizing many diseases has increased and diagnostic techniques evaluating bone health have progressively improved, the problem of low bone mass/quality in children and adolescents has attracted more and more attention, and the body evidence that there are groups of children who may be at risk of osteoporosis has grown. This interest is linked to an increased understanding that a higher peak bone mass (PBM) may be one of the most important determinants affecting the age of onset of osteoporosis in adulthood. This review provides an updated picture of bone pathophysiology and characteristics in children and adolescents with paediatric osteoporosis, taking into account the major causes of primary osteoporosis (PO) and evaluating the major aspects of bone densitometry in these patients. Finally, some options for the treatment of PO will be briefly discussed.

The role of Notch signaling in bone development and disease

During the last decade a considerable amount of data have been accumulated regarding the role of intracellular signaling pathways in the pathogenesis of human diseases. One of these, Notch signaling, well known for its significance in cellular development and tissue morphogenesis, has been increasingly recognized as a crucial participant in the pathogenetic mechanisms underlying certain skeletal disorders. A better understanding of the biology and regulation of this multifaceted pathway is considered an important step towards clarification of the pathogenesis of various skeletal diseases and the development of novel targets for therapeutic purposes.

Detecting genetic association of common human facial morphological variation using high density 3D image registration

Human facial morphology is a combination of many complex traits. Little is known about the genetic basis of common facial morphological variation. Existing association studies have largely used simple landmark-distances as surrogates for the complex morphological phenotypes of the face. However, this can result in decreased statistical power and unclear inference of shape changes. In this study, we applied a new image registration approach that automatically identified the salient landmarks and aligned the sample faces using high density pixel points. Based on this high density registration, three different phenotype data schemes were used to test the association between the common facial morphological variation and 10 candidate SNPs, and their performances were compared. The first scheme used traditional landmark-distances; the second relied on the geometric analysis of 15 landmarks and the third used geometric analysis of a dense registration of ∼30,000 3D points. We found that the two geometric approaches were highly consistent in their detection of morphological changes. The geometric method using dense registration further demonstrated superiority in the fine inference of shape changes and 3D face modeling. Several candidate SNPs showed potential associations with different facial features. In particular, one SNP, a known risk factor of non-syndromic cleft lips/palates, rs642961 in the IRF6 gene, was validated to strongly predict normal lip shape variation in female Han Chinese. This study further demonstrated that dense face registration may substantially improve the detection and characterization of genetic association in common facial variation.

Heritability of human facial appearance is an intriguing question to the general public and researchers. Although it is known that some facial features are highly heritable, the exact genetic basis is unknown. Previous studies used simple linear measurements such as landmark distances, to evaluate the facial shape variation. Such approaches, although easy to carry out, may lack statistical power and miss complex morphological changes. In this study, we utilized a new 3D face registration method that enables subtle differences to be detected at high resolution 3D images. Based on this, we tried to test and characterize the associations of 10 candidate genetic variants to common facial morphological variations. Different types of phenotype data were extracted and compared in the association tests. Our results show that geometry based data performed better than simple distance based data. Furthermore, high density geometric data outstood the others in capturing small shape changes and modeling the 3D face visualization. Interestingly, a genetic variant from IRF6 gene, which is also a well-known risk factor of non-syndrome cleft lip, was found to strongly predispose the mouth shape in Han Chinese females.

An unusual presentation of diabetic ketoacidosis in familial hajdu-cheney syndrome: a case report

A 21-year-old man with diabetic ketoacidosis (DKA) displayed short and clubbed fingers and marked eyebrow, which are typical of Hajdu-Cheney Syndrome (HCS). Laboratory findings confirmed type 1 diabetes mellitus (DM). After conservative care with hydration and insulin supply, metabolic impairment was improved. Examinations of bone and metabolism revealed osteoporosis and craniofacial abnormalities. The mutation (c.6443T>G) of the NOTCH2 gene was found. The patient was diagnosed with HCS and DM. There may be a relationship between HCS and DM, with development of pancreatic symptoms related to the NOTCH2 gene mutation.

Hajdu-cheney syndrome with osteomyelitis of mandible, calcification of falx cerebri and palatal groove

Hajdu-Cheney syndrome is a very rare, inherited, autosomal dominant, skeletal dysplasia associated with characteristic craniofacial and dental features, primary acroosteolysis of the terminal phalanges and generalized osteoporosis. A 37-year-old male patient presented with features of osteomyelitis of the right mandible and typical features of Hajdu-Cheney syndrome. The patient also had calcification of the falx cerebri and an unusual median palatal groove, which has not been reported in Hajdu-Cheney syndrome before. The clinical and radiological features, differential diagnosis, and management of the patient are presented.

Mutations in NOTCH2 in patients with Hajdu-Cheney syndrome

The Hajdu-Cheney syndrome is a very rare disease that affects several organ system, leading to severe osteoporosis and other abnormalities. We describe clinical and genetic findings of nine patients with this disease.

INTRODUCTION

The Hajdu-Cheney syndrome (HCS) is a rare autosomal dominant disorder characterized by severe osteoporosis, acroosteolysis of the distal phalanges, renal cysts, and other abnormalities. Recently, heterozygous mutations in NOTCH2 were identified as the cause of HCS.

METHODS

Nine patients with typical presentations of HCS took part in this study: five affected patients from two small families and four sporadic cases. Peripheral blood DNA was obtained and exome sequencing performed in one affected individual per family and in all four sporadic cases. Sanger sequencing confirmed mutations in all patients.

RESULTS

One of the identified mutations was introduced in a plasmid encoding NOTCH2. Wild-type and mutant NOTCH2 were transiently expressed in HEK293 cells to assess intracellular localization after ligand activation. Deleterious heterozygous mutations in the last NOTCH2 exon were identified in all patients; five of the six mutations were novel.

CONCLUSION

Consistent with previous reports, all mutations are predicted to result in a loss of the proline/glutamic acid/serine/threonine sequence, which harbors signals for degradation, therefore suggesting activating mutations. One of the six mutations furthermore predicted disruption of the second nuclear localization signal of NOTCH2, but the mutant revealed normal nuclear localization after transfection, which is consistent with the proposed gain-of-function mechanism as the cause of this autosomal dominant disease. Our findings confirm that heterozygous NOTCH2 mutations are the cause of HCS and expand the mutational spectrum of this disorder.

Notch signaling and bone remodeling

Notch signaling plays context-dependent roles in the development and maintenance of many cell types and tissues in mammals. In the skeleton, both osteoblasts and osteoclasts require Notch signaling for proper differentiation and function, and the specific roles of Notch are dependent on the differentiation status of the cell. The recent discovery of activating NOTCH2 mutations as the cause of Hajdu-Cheney syndrome has highlighted the significance of Notch signaling in human bone physiology.

Clinical consequences in truncating mutations in exon 34 of NOTCH2: report of six patients with Hajdu-Cheney syndrome and a patient with serpentine fibula polycystic kidney syndrome

It is debatable whether Hajdu-Cheney syndrome (HCS) and serpentine fibula-polycystic kidney syndrome (SFPKS) represent a single clinical entity with a variable degree of expression or two different entities, because both disorders share common clinical and radiological manifestations, including similar craniofacial characteristics, and defective bone mineralization. Since it was shown that heterozygous truncating mutations in NOTCH2 are responsible for both HCS and SFPKS, 37 patients with HCS and four patients with SFPKS are reported. To elucidate the clinical consequences of NOTCH2 mutations, we present detailed clinical information for seven patients with truncating mutations in exon 34 of NOTCH2, six with HCS and one with SFPKS. In addition, we review all the reported patients whose clinical manifestations are available. We found 13 manifestations including craniofacial features, acroosteolysis, Wormian bones, and osteoporosis in >75% of NOTCH2-positive patients. Acroosteolysis was observed in two patients with SFPKS and bowing fibulae were found in two patients with HCS. These clinical and molecular data would support the notion that HCS and SFPKS are a single disorder.

Severe osteoporosis and mutation in NOTCH2 gene in a woman with Hajdu-Cheney syndrome

Hajdu-Cheney syndrome (HCS) is a rare genetic disorder characterised by acro-osteolysis, skull deformation and generalised osteoporosis. Recently, truncating mutations in the last exon of NOTCH2, a protein-coding gene, were found to be responsible. We present the case of a young woman with HCS in whom clinical and radiologic diagnosis was confirmed with DNA tests.

The coding genome of splenic marginal zone lymphoma: activation of NOTCH2 and other pathways regulating marginal zone development

Splenic marginal zone lymphoma (SMZL) is a B cell malignancy of unknown pathogenesis, and thus an orphan of targeted therapies. By integrating whole-exome sequencing and copy-number analysis, we show that the SMZL exome carries at least 30 nonsilent gene alterations. Mutations in NOTCH2, a gene required for marginal-zone (MZ) B cell development, represent the most frequent lesion in SMZL, accounting for ∼20% of cases. All NOTCH2 mutations are predicted to cause impaired degradation of the NOTCH2 protein by eliminating the C-terminal PEST domain, which is required for proteasomal recruitment. Among indolent B cell lymphoproliferative disorders, NOTCH2 mutations are restricted to SMZL, thus representing a potential diagnostic marker for this lymphoma type. In addition to NOTCH2, other modulators or members of the NOTCH pathway are recurrently targeted by genetic lesions in SMZL; these include NOTCH1, SPEN, and DTX1. We also noted mutations in other signaling pathways normally involved in MZ B cell development, suggesting that deregulation of MZ B cell development pathways plays a role in the pathogenesis of ∼60% SMZL. These findings have direct implications for the treatment of SMZL patients, given the availability of drugs that can target NOTCH, NF-κB, and other pathways deregulated in this disease.