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

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.

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.

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.