ESPE Abstracts

Background: XLHR is due to mutations in the PHEX gene leading to unregulated production of FGF23, hence hypophosphatemia and decreased renal 1,25OH-vitamin D hydroxylation. Amongst other features, XLHR is characterized by leg bowing of variable severity. Phosphate supplements and oral 1,25OH-vitamin D, partially or, in some cases, fully restore the limb straightness. For severe or residual limb deformities, orthopaedic surgery may be recommended.Objectiv...

Background: Pseudohypoparathyroidism type 1A (PHP1A) and PseudoPHP are caused respectively by maternal and paternal mutations involving those GNAS exons that encode the alpha-subunit of the stimulatory G protein (Gsα). Common to different forms of PHP1B is a loss-of-methylation (LOM) at one or several maternal GNAS exons, which likely reduces Gsα expression in certain tissues. In most autosomal dominant PHP1B variants (AD-PHP1B), LOM is restricted t...

Background: For adult patients who do not meet indications to surgery, the calcimimetic cinacalcet is approved for primary hyperparathyroidism (HPT), decreasing calcium and parathyroid hormone (PTH) levels. This drug is largely used in adults, but may be a challenge in daily practice in children, because of the risk of hypocalcemia, increased QT interval and drug interactions. A few pediatric cases have highlighted its potential interest in children with HPT; ...

Background: Disproportionate short stature is seen in most individuals with X-linked hypophosphatemia (XLH). Vitamin D and phosphate supplementation can improve growth slightly. Burosumab showed minimal improvement of growth in older children. No growth data of XLH children that started burosumab at a very young age, i.e., between 1 and 4 years, are available.Methods: We included 17 XLH children (11 boys) who started bur...

Background: Pycnodysostosis is a very rare autosomal recessive skeletal dysplasia caused by cathepsin K deficiency. It is characterized by extreme short stature resulting in an adult height in males typically <150 cm and in females <134 cm. Bone-fragility and frequent fractures are present. There are few case-reports on the effects of GH treatment.Objective: To evaluate the effect and safety of GH in 6 patients wit...

Background: Pseudohypoparathyroidism 1A, newly classified as inactivating PTH/PTHrP signaling disorder type 2 (iPPSD2), is defined by resistance to parathyroid hormone, short stature and early-onset obesity. Short stature is caused by skeletal dysplasia and additionally, in some cases, also by the coexistence of growth hormone deficiency, as other hormonal resistances might be present (e.g. thyroid-stimulating hormone, growth hormone releasing hormone (GHRH), ...

In XLH, excess fibroblast growth factor 23 (FGF23) causes hypophosphatemia and consequent rickets, skeletal deformities, and growth impairment. The efficacy and safety of burosumab, a fully human monoclonal antibody against FGF23, was evaluated in two Phase 2 trials in children with XLH. In CL201, 52 children with XLH (5–12 years old, Tanner ≤2) were randomized 1:1 to receive subcutaneous burosumab every 2 (Q2W) or 4 (Q4W) weeks, with doses titrated up to 2 mg/kg to...

Mineralization defects and paradoxical mineralizing enthesopathies are hallmarks of X-linked Hypophosphatemia (XLH), a rare skeletal disease caused by inactivating mutations in the PHEX gene (Phosphate-regulating endopeptidase homolog, X-linked). The current medical treatment, which consist in oral phosphorus supplementation and active vitamin D analogues, aimed at counteracting consequences of FGF23 excess and is commonly prescribed from early childhood to the end of...

Hypophosphatasia (HPP) is a rare, inherited, systemic disease caused by mutation(s) of the ALPL gene encoding tissue-nonspecific alkaline phosphatase (ALP), resulting in deficient ALP activity. Asfotase alfa is an enzyme replacement therapy approved for treatment of patients with pediatric-onset HPP. The global HPP Registry is an observational, prospective, multinational study (NCT02306720; EUPAS13514) established to collect real world clinical data from patients of a...

Introduction: X-linked hypophosphatemia (XLH) is a rare, inherited disease that affects approximately 1 in 20,000 individuals. XLH 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. Children with XLH experience abnormal bone development, rickets, osteomalacia, impaired growth, dental abscesses, craniosynostosis ...