Bone Abstracts

GNAS-Gsalpha based disorders lead to heterogeneous diseases associated with abnormal bone development via two distinct mechanisms. At the level of the growth plate in bones, the PTHrP/PTH1R/Gsalpha/cAMP/PKA/PDE signalling pathway regulates endochondral ossification. PTHrP binds to the PTH receptor (PTH1R) which then couples with the stimulatory G protein (Gsalpha) leading to cAMP formation. cAMP binds to the regulatory 1A subunits (R1A) of the PKA. Upon binding the catalytic s...

Biographical DetailsAnya RothenbuhlerAnya Rothenbuhler became MD at the Faculty of Medicine Lille 2 in France in 2003 with a primary specialization in Pediatrics. She then became assistant Professor in the Pediatric Endocrinology Department in Cochin-Saint Vincent de Paul Hospital, Université Paris Descartes and trained to become a pediatric en...

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...

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: 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...

Background: Most patients with hypoparathyroidism are controlled under conventional treatment with calcium and vitamin D analogues. However, this treatment may be difficult to manage, especially in patients with ADHH who have an increased risk of nephrocalcinosis and chronic renal insufficiency. ADHH is caused by activating mutations in the calcium-sensing receptor (CaSR) resulting in suppressed PTH secretion and decreased calcium reabsorption within the thick ascending limb o...

Mutations in PHEX and specific missense mutations of FGF23 result in elevated circulating FGF23 and hypophosphatemic rickets, respectively X-linked hypophosphatemic rickets (XLHR) and autosomal dominant HR (ADHR). FGF23, secreted by osteoblasts and osteocytes, regulates phosphate handling and vitamin D metabolism through its action on kidney. Extra renal effects of FGF23, including bone, have been very recently suspected mainly from overexpression or underexpression of FGF23 i...

Background/aim: X-linked hypophosphatemia (XLH) is a rare disease characterized by low phosphate level. Scientific evidence points to link between hypophosphatemia and obesity in general population. The aim of our longitudinal observational study was to investigate the prevalence of obesity and associated factors in a large cohort of children with XLH.Patients/methods: We selected 172 XLH-children of 5–20 years (113 girls/59 boys). Anthropometric pa...

Background and aim: Burosumab is a monoclonal antibody against anti-FGF23, which has been recently approved for treatment of X-linked hypophosphatemia (XLH). Beyond clinical trials, little is known about its efficacy/safety in clinical practice which is the aim of study.Patients/Methods: 39 children with XLH were switched from conventional therapy to burosumab (starting dose 0.4 mg/kg), because of following indications: non-responder to conventional ther...