Exploratory use of romosozumab for osteoporosis in a patient with Hajdu-Cheney syndrome: a case report.

Hajdu-Cheney syndrome (HCS) is an inherited skeletal disorder caused by mutations in the Notch homolog protein 2 gene (NOTCH2). Treatment of this rare disease is challenging because there are no established guidelines worldwide. Previous case reports using bisphosphonates, denosumab, or teriparatide suggested that curative treatment for HCS did not exist yet in terms of preventing the disease progression. Therefore, the efficacy of romosozumab for osteoporosis in patients with HCS needs to be evaluated. Herein, we report the case of a 43-year-old woman who had progressive acro-osteolysis and repeated fractures since the age of 29 years. Next-generation sequencing confirmed HCS with a mutation at nucleotide 6758G>A, leading to Trp2253Ter replacement in NOTCH2. Romosozumab treatment was initiated because she had already received bisphosphonate for more than 10 years at other hospitals. After 1 year of romosozumab treatment, the bone mineral density (BMD) increased by 10.2%, 6.3%, and 1.3%, with Z scores of -2.9, -1.6, and -1.2 at the lumbar spine, femoral neck, and total hip, respectively. In addition, C-telopeptide was suppressed by 26.4% (0.121 to 0.089 ng/mL), and procollagen type I N-terminal propeptide increased by 18.7% (25.2 to 29.9 ng/mL). This was the first report of romosozumab treatment in patient with osteoporosis and HCS in Korea. One year of romosozumab treatment provided substantial gains in BMD with maintaining the last acro-osteolytic status without deteriorating, representing a possible treatment option for HCS.

A mutation in NOTCH2 gene first associated with Hajdu-Cheney syndrome in a Greek family: diversity in phenotype and response to treatment.

INTRODUCTION: Hajdu-Cheney Syndrome (HCS) is a rare genetic autosomal dominant disorder, characterized by distinctive facial features, acroosteolysis, and severe osteoporosis. Very rarely HCS is associated with polycystic kidney disease, splenomegaly or Crohn's disease (CD). It is caused by gain-of-function mutations in NOTCH2 gene. Treatment with bisphosphonates or denosumab is reported to result in BMD increase. OBJECTIVE: We report a mutation in exon 34 of NOTCH2 gene, in a Greek pedigree, with diverse phenotypes among members. DESCRIPTION OF THE PEDIGREE: The 48-year-old mother had a history of a T12 vertebral fracture, postpartum at the age of 21 and two subsequent uneventful full-term pregnancies and never received treatment. Her 29-year-old son, presented with severe osteoporosis and multiple morphological vertebral fractures. Her 21-year-old daughter had recurrent vertebral fractures starting at 10 years of age. At 17 years, she developed severe CD, resistant to treatment with biologic agents, and functional hypothalamic hypogonadism. One male pedigree died of cystic fibrosis. All subjects bore the typical facial characteristics and acroosteolysis, while none had splenomegaly or renal defects. Zoledronate infusion led to BMD increase. GENETIC TESTING: Mutation in c.6758 G > A (NM_008163.1), leading to a Trp2253Ter replacement. This mutation has been reported as possibly pathogenic (SCV000620308), but not in association with HCS. CONCLUSIONS: Bone involvement can present with diverse severity in the same pedigree, ranging from low BMD to multiple fragility fractures. Antiresorptive therapy improves BMD, but its anti-fracture efficacy remains to be shown. The presence of CD might indicate the significant role of NOTCH2 signaling in different tissues.

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.

An Antibody to Notch2 Reverses the Osteopenic Phenotype of Hajdu-Cheney Mutant Male Mice.

Notch receptors play a central role in skeletal development and bone remodeling. Hajdu-Cheney syndrome (HCS), a disease characterized by osteoporosis and fractures, is associated with gain-of-NOTCH2 function mutations. To study HCS, we created a mouse model harboring a point 6955C>T mutation in the Notch2 locus upstream of the proline, glutamic acid, serine, and threonine domain, leading to a Q2319X change at the amino acid level. Notch2Q2319X heterozygous mutants exhibited cancellous and cortical bone osteopenia. Microcomputed tomography demonstrated that the cancellous and cortical osteopenic phenotype was reversed by the administration of antibodies generated against the negative regulatory region (NRR) of Notch2, previously shown to neutralize Notch2 activity. Bone histomorphometry revealed that anti-Notch2 NRR antibodies decreased the osteoclast number and eroded surface in cancellous bone of Notch2Q2319X mice. An increase in osteoclasts on the endocortical surface of Notch2Q2319X mice was not observed in the presence of anti-Notch2 NRR antibodies. The anti-Notch2 NRR antibody decreased the induction of Notch target genes and Tnfsf11 messenger RNA levels in bone extracts and osteoblasts from Notch2Q2319X mice. In vitro experiments demonstrated increased osteoclastogenesis in Notch2Q2319X mutants in response to macrophage colony-stimulating factor and receptor activator of nuclear factor-κB ligand, and these effects were suppressed by the anti-Notch2 NRR. In conclusion, Notch2Q2319X mice exhibit cancellous and cortical bone osteopenia that can be corrected by the administration of anti-Notch2 NRR antibodies.

Hajdu Cheney Syndrome; report of a novel NOTCH2 mutation and treatment with denosumab.

Notch receptors play a central role in skeletal development and homeostasis. Hajdu Cheney Syndrome (HCS) is a rare disease associated with mutations of NOTCH2 that lead to the translation of a truncated, presumably stable, NOTCH2 protein. As a consequence, a gain-of-NOTCH2 function is manifested. We report a subject presenting with HCS and her child, both harboring a new heterozygous mutation in Exon 34 of NOTCH2 upstream of the PEST domain. The subject presented with osteoporosis, fractures, acroosteolysis and splenomegaly but did not have neurological complications, cardiovascular defects or polycystic kidneys. Sequencing of genomic DNA revealed a previously unreported mutation at nucleotide 6667C>T leading to a Gln2223Ter protein product in the subject and her son. Preclinical studies have demonstrated that the bone loss in HCS is secondary to enhanced osteoclastogenesis and bone resorption, and the same mechanism may operate in humans. Accordingly, the case we report was treated and responded to therapy with denosumab with an increase in bone mineral density (BMD). However, acroosteolysis progressed and was not modified by denosumab. In conclusion, we report a case of HCS associated with a novel mutation in NOTCH2 and its response to denosumab on BMD.

A very rare cause of acro-osteolysis: Hajdu-Cheney syndrome.

Acro-osteolysis is not uncommon and occurs in several conditions. Additional clinical and paraclinical findings and sometimes the performance of molecular tests can help to clarify the diagnosis. Here, we report the case of a 36-year-old woman who was referred to our department because of acute pain in the extremity of the left index finger. However, subsequent clinical examination also revealed short digits with pseudo-clubbing related to acro-osteolysis. Furthermore, severe osteoporosis, a moderate dysmorphic face, joint hypermobility, biological variables within normal ranges and her clinical history led us to consider the diagnosis of Hajdu-Cheney syndrome. Molecular analysis confirmed the diagnosis with the identification of a mutation in the NOTCH2 gene. The patient received bisphosphonate therapy, which resulted in some clinical and biological improvement 12 months later.

Multicentric osteolysis with nodulosis and arthropathy (MONA) with cardiac malformation, mimicking polyarticular juvenile idiopathic arthritis: case report and literature review.

UNLABELLED: The 'vanishing bone' syndrome multicentric osteolysis with nodulosis and arthropathy (MONA) is a rare chronic skeleton disorder caused by matrix metalloproteinase 2 (MMP2) deficiency, mimicking erosive polyarticular juvenile idiopathic arthritis. MONA is characterised by facial dysmorphism, subcutaneous fibrocollagenous nodules, carpal and tarsal osteolysis and interphalangeal joint erosions. We present the case of a 5-year-old boy with double outlet right ventricle, ventricular septal defect, coarctation of the aorta and MONA. Previously, a total of 24 cases of MONA have been reported of which six also had congenital cardiac malformations. Despite treatment attempts of our patient with methotrexate, eternacept and prednisolone, serial X-ray studies documented continuous severe bone degeneration. CONCLUSION: The case documents the natural history of MONA and establishes a link between MMP2 deficiency and heart development, and given the recurring cardiac association, we suggest that all MONA patients be examined for possible cardiac defects.

Two-year cyclic infusion of pamidronate improves bone mass density and eliminates risk of fractures in a girl with osteoporosis due to Hajdu-Cheney syndrome.

Hajdu-Cheney syndrome (HCS) is a rare disorder principally characterized by acro-osteolysis, distinctive craniofacial and skull changes, dental anomalies and short stature. A common finding in HCS patients is secondary osteoporosis that progresses over time and contributes to various skeletal problems, especially fractures. Although autosomal dominant inheritance has been documented in several families, sporadic (non-familial) cases have also been reported. Here, a case of a 9-year-old girl with familial HCS and multiple spinal fractures, who has been effectively treated with pamidronate, is presented. This is the first report of a beneficial effect of intravenous bisphosphonate administration on a child with HCS-related osteoporosis.

Effect of zoledronic acid on acro-osteolysis and osteoporosis in a patient with Hajdu-Cheney syndrome.

Hajdu-Cheney syndrome is a rare, autosomal dominant skeletal dysplasia marked by acro-osteolysis of the distal phalanges and severe osteoporosis. Although there are more than 60 reports published to date, proper treatment and subsequent outcome have been scarce. Herein, we report a progress of anti-resorptive therapy with zoledronic acid, in a woman with Hajdu-Cheney syndrome. Results suggest that anti-resorptive therapy may be important in delaying the progress of osteoporosis and preventing fractures, but not necessarily acro-osteolysis itself.

Multicentric carpal-tarsal osteolysis with nephropathy treated successfully with cyclosporine A: a case report and literature review.

Multicentric carpal-tarsal osteolysis is a rare skeletal disorder characterized by osteolysis of the metacarpal, carpal, and tarsal bones and leading to crippling joint deformities. Progressive nephropathy occurs in more than half the cases. All previously reported series with renal biopsies showed only end-stage renal disease on histological examination because of the late presentation to nephrologists. Accurate diagnosis of the underlying renal pathological state therefore has not been possible. We report the first case in which early and sequential renal biopsies were performed. These show the renal lesion to be focal and segmental glomerulosclerosis, which was treated successfully with cyclosporine A.

Integrated anti-remodeling and anabolic therapy for the osteoporosis of Hajdu-Cheney syndrome.

Hajdu-Cheney syndrome (MIM 102500) is a rare skeletal dysplasia marked by severe generalized osteoporosis and focal bone loss (acro-osteolysis). Osteoporosis treatment outcome has been reported only once previously. Reported herein is the biochemical and densitometric response to integrated anti-remodeling and anabolic therapy in a woman with Hajdu-Cheney syndrome. Results suggest dissociation of bone formation from bone resorption resulting in dramatic increases in bone mineral density without clinical evidence of activated osteoporosis.