Bone Abstracts

Acrodysostosis refers to a group of rare chondrodysplasia that share severe brachydactyly, short stature and nasal hypoplasia. Through a candidate gene approach or exome sequencing, heterozygous mutations in PRKAR1A or in PDE4D, respectively, have been identified in patients with acrodysostosis. PRKAR1A encodes the regulatory subunit of the protein kinase A (PKA), which allows, upon binding of cAMP, phosphorylation of target proteins by the catalytic subunit ...

Biographical DetailsDr A Linglart is a Paediatric Endocrinologist working at the Hôpital St Vincent de Paul in Parism, France. She has a special interest in rare diseases....

Background and objectives: X-linked hypophosphatemic rickets (XLH) is the most common form of inheritable rickets. The treatment of rickets is monitored via laboratory tests such as alkaline phosphatase (ALP), clinical features, and plain X-rays. The objectives of this study were to describe the MRI features in XLH and to look for correlations between those features and XLH activity.Study design: Twenty-seven patients (younger than 18 years with XLH due ...

Rett (RTT) syndrome is a neurodevelopmental disorder that affects girls almost exclusively. The majority are related to mutations in the MECP2 gene.Patients with RTT syndrome have a high incidence of fractures that can occur at a young age. One of the objectives of this study was to identify clinical, radiographic and biological parameters associated to fracture incidence.89 RTT patients bearing a MECP2 mutation who had no...

X-linked Hypophosphatemia (XLH), the most common heritable form of rickets, is a disorder of renal phosphate wasting caused by high circulating levels of fibroblast growth factor 23 (FGF23) that impairs normal phosphate reabsorption in the kidney and production of the active form of vitamin D. Affected children present with hypophosphatemia resulting in rickets, bowing of the legs and short stature. Limited information is available about the disease burden in children with XLH...

Background: Rett Syndrome (RS) is a disabling condition due to mutations in MECP2. Girls affected with RS are at risk of developing osteoporosis and fractures at a young age because of their lack of mobility and through a direct effect of MECP2 on bone mineralization. In these girls, bone fragility inflicts pain and may seriously impair the quality of life.Objective: To retrospectively assess the effect of IV bisphosphonates on fracture, bone mineral den...

Background: Hypocalcemia presenting in adolescence is rare. Most common etiology is autoimmune hypoparathyroidism. Pseudohypoparathyroidism (PHP) is a rare group of disorders characterized by end-organ resistance to parathyroid hormone (PTH), and other hormones, such as TSH, with or without features of Albright’s hereditary osteodystrophy.Case presentation: A 14-year-old boy presented complaining of fatigue and spontaneous carpal spasms in associati...

Background: X-linked hypophosphatemic rickets (XLHR) represents the most common form of hypophosphatemia.Aim: The aim of this prospective study was to describe and analyze the incidence of cranial and cervico-occipital junction (COJ) anomalies in a series of children with XLHR.Patients and methods: Seventeen children (13 girls, 4 boys, mean age 7.3 years) followed for XLHR at the French national reference center for rare diseases o...

Introduction: The platform of expertise for rare diseases Paris-Sud is an organization created at the end of 2014. It brings together 21 reference centers for rare diseases of the university hospitals Paris-Sud, 12 diagnostic and research laboratories, a biological resource center and several patient associations.Methods: A multidisciplinary team (a communication officer, a bio-informatician, a geneticist, clinical research associates, an administrative ...

Mutations in the PHEX gene cause X-linked familial hypophosphatemic rickets (XLH) with severe bone (osteomalacia) and tooth abnormalities being the distinguishing features of this disease. The PHEX mutations lead to an increase in ASARM peptides (acidic serine- and aspartate-rich motif) and osteopontin fragments which inhibit bone extracellular matrix mineralization. MEPE-derived ASARM has been shown to accumulate in tooth dentin of patients with XLH where it may impair dentin...