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

Bone mineral density and microarchitecture improvement in a young patient with Hajdu-Cheney syndrome and autosomal dominant polycystic kidney disease treated with alendronate

Introduction

Osteoporosis, typically seen in postmenopausal women, can also affect younger individuals, a condition known as Early-Onset Osteoporosis (EOOP). EOOP may be secondary to various conditions or arise from rare genetic disorders such as Hajdu-Cheney Syndrome (HCS), characterized by systemic bone involvement and fragility fractures.

Case Report

A 14-year-old male presented with a distal left femur fragility fracture. His medical history included spina bifida and bilateral tarsal coalition, with no family history of osteoporosis, and polycystic kidneys associated with a positive family history of autosomal dominant polycystic kidney disease (ADPKD). Laboratory tests were unremarkable, but dual X-ray absorptiometry (DXA) revealed low bone mineral density (BMD), and high resolution peripheral quantitative computed tomography (HR-pQCT) showed decreased volumetric bone density (vBMD), particularly in the cortical bone. At age 17, his kidneys were cystic and mildly enlarged. Whole exome sequencing revealed a pathogenic variant in NOTCH2, confirming the diagnosis of HCS, and a very likely causative variant in PKD1, supporting the diagnosis of ADPKD.The treatment regimen included weekly alendronate, impact exercise, a calcium-rich diet, and vitamin D supplementation. After 3 years, follow-up DXA and HR-pQCT demonstrated significant improvements in BMD and vBMD, mainly in the cortical bone.

Discussion

This case highlights the effectiveness of alendronate in managing osteoporosis in a patient with HCS and ADPKD, despite the current lack of strong supportive evidence. Long-term monitoring revealed substantial improvements in bone density and microarchitecture, underscoring the importance of early diagnosis and intervention for genetic causes of osteoporosis to prevent fracture-related morbidity.

Four SNPs in the untranslated region of the NOTCH2 gene involved in reproductive traits in fertile and anestrum Holstein Friesian cattle

BACKGROUND

There are no studies belong NOTCH2 gene polymorphism in relation to reproductive and productive traits in Holstein cattle. The objective of the present study was to investigate the effect of NOTCH2 gene polymorphisms on productive and reproductive performance of fertile and anestrum cattle.

METHODS

The cattle were classified into anestrus for 3-12 months postpartum (n = 115, 37.7%) and normal cyclic fertile (n = 190, 62.3%). Age at 1st calving, calving interval, calf birth weight, milk yield and days of milking data were obtained from the farm records for all animals. Blood samples were collected from fertile and anestrum animals for DNA extraction and the PCR as well as single-strand conformation polymorphism techniques (SSCP) were performed for detection of the NOTCH2 gene polymorphism.

RESULTS

The sequencing results showed that NOTCH2 gene in cattle is polymorphic with 5 genotypes AA, AG, GG, CC and CT. Four novel SNPs as transition single base substitution mutations were detected at 3: 23,192,033 (A/G), 3:23192149 (C/T), 3:23192071 (C/T) and 3:23192143 (G/A). GG genotype of NOTCH2 gene was associated with shorter calving interval and heavier calf birth weight in both fertile and anestrum cattle.

CONCLUSIONS

NOTCH2 gene in cattle could be used as a genetic marker involved in reproductive traits in both fertile and anestrum cattle.

First case of Hajdu-Cheney syndrome in Lithuania caused by novel NOTCH2 gene likely pathogenic variant

Hajdu-Cheney syndrome (HCS) is an extremely rare autosomal dominant skeletal disorder. The prevalence rate of less than 1 case per 1,000,000 newborns and only 50 cases were reported in the medical literature. HCS is characterized by progressive bone resorption in the distal phalanges (acro-osteolysis), progressive osteoporosis, distinct craniofacial changes, dental anomalies, and occasional association with renal abnormalities. HCS is caused by pathogenic variants in the NOTCH2 gene, 34th exon. We report first familial case of HCS caused by likely pathogenic variant of NOTCH2 gene c.6449delC, p.(Pro2150LeufsTer5).

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.