X-linked hypophosphatemia (XLH), due to a PHEX gene mutation, is the most common genetic form of rickets and osteomalacia. Manifestations in children consist of rickets, lower-limb bone deformities, ...bone pain, failure to thrive, dental abscesses, and/or craniostenosis. Adults may present with persistent bone pain, early osteoarthritis, hairline fractures and Looser zones, enthesopathy, and/or periodontitis. Regardless of whether the patient is an infant, child, adolescent or adult, an early diagnosis followed by optimal treatment is crucial to control the clinical manifestations, prevent complications, and improve quality of life. Treatment options include active vitamin D analogs and phosphate supplementation to correct the 1.25(OH)2 vitamin D deficiency and to compensate for the renal phosphate wasting, respectively. The recently introduced FGF23 antagonist burosumab is designed to restore renal phosphate reabsorption by the proximal tubule and to stimulate endogenous calcitriol production. In Europe, burosumab is licensed for use in pediatric patients older than 1 year who have XLH. This review discusses the diagnosis and treatment of XLH and describes the indications of the various available treatments.
Abstract
Context
Musculoskeletal complications are the main manifestations in adults with X-linked hypophosphatemia (XLH). Enthesopathy significantly impairs quality of life.
Objective
To identify ...the risk factors associated with the development and progression of spinal enthesopathies in adults with XLH.
Design and setting
We conducted a retrospective study in the French Reference Center for Rare Diseases of the Calcium and Phosphate Metabolism.
Patients
Adults XLH patients with 2 EOS® imaging performed at least 2 years apart at the same center between June 2011 and March 2022. The progression of enthesopathies was defined as a new enthesopathy at least 1 intervertebral level in patients with or without presence of enthesopathy at baseline.
Main outcome measures
Demographic, treatment, PHEX mutation with the progression of enthesopathies.
Results
Fifty-one patients (66.7% of women, mean age 42.1 ± 13.4 years) underwent 2 EOS imaging with an average interval of 5.7 (± 2.31) years.
Progression of spinal enthesopathies was observed in 27 (52.9%) patients. In univariate analysis, patients with a progression of spinal enthesopathies were significantly older (P < .0005), were significantly older at treatment initiation (P = .02), presented with dental complications (P = .03), received less frequently treatment during childhood with phosphate and/or vitamin D analogs (P = .06), and presented more frequently with hip osteoarthritis (P = .002) at baseline. In multivariate analysis, none of these factors was associated with a progression of spinal enthesopathies.
Conclusion
This study confirms the high proportion of patients with a progression of spinal enthesopathies. Age seems to be the main factor associated with progression.
Abstract Context Pseudohypoparathyroidism (PHP) refers to a group of rare hereditary disorders associated with resistance to parathyroid hormone (PTH) and other hormones now termed inactivating ...PTH/PTHrP disorders (iPPSD). Hypercalcitoninemia has been seldom reported in small series. Objective Our aim was to investigate the characteristics of hypercalcitoninemia in pediatric and adult patients with PHP/iPPSD. Methods We retrospectively collected data from 2 cohorts from 2 European endocrinology tertiary centers: the pediatric cohort comprised 88 children with available calcitonin (CT) measurements; the adult cohort included 43 individuals with simultaneous CT and PTH measurements. Results In the pediatric cohort, 65.9% had hypercalcitoninemia (median CT 15 ng/L); in the adult cohort 53.5% (mean CT 21.6 ng/L). There was no difference between CT in pediatric and adult population; we observed stable CT levels over a median follow-up of 134.5 months in adults. Notably, no correlations were detected between CT and PTH levels. Other etiologies of hypercalcitoninemia were excluded; adult patients underwent regular thyroid ultrasound to screen for medullary thyroid cancer (MTC). We performed 20 calcium stimulation tests in adult patients. While there was a significant difference in basal and peak CT between our patients, healthy subjects, and subjects with MTC, there was no difference with patients with C-cell hyperplasia. Conclusion This study underscores the common occurrence of hypercalcitoninemia in both pediatric and adult patients with PHP/iPPSD, in particular with subtypes iPPSD2 and iPPSD3. Furthermore, these patients show hyperresponsiveness to calcium stimulation tests falling between healthy subjects and patients with MTC. These findings contribute to the understanding of CT dynamics in the context of PHP/iPPSD.
Abstract
Background
Pseudohypoparathyroidism (PHP) and related disorders newly referred to as inactivating PTH/PTHrP signaling disorders (iPPSD) are rare endocrine diseases. Many clinical features ...including obesity, neurocognitive impairment, brachydactyly, short stature, parathyroid hormone (PTH) resistance, and resistance to other hormones such as thyroid-stimulating hormone (TSH) have been well described, yet they refer mainly to the full development of the disease during late childhood and adulthood.
Objective
A significant delay in diagnosis has been reported; therefore, our objective is to increase awareness on neonatal and early infancy presentation of the diseases. To do so, we analyzed a large cohort of iPPSD/PHP patients.
Methods
We included 136 patients diagnosed with iPPSD/PHP. We retrospectively collected data on birth and investigated the rate of neonatal complications occurring in each iPPSD/PHP category within the first month of life.
Results
Overall 36% of patients presented at least one neonatal complication, far more than the general population; when considering only the patients with iPPSD2/PHP1A, it reached 47% of the patients. Neonatal hypoglycemia and transient respiratory distress appeared significantly frequent in this latter group, ie, 10.5% and 18.4%, respectively. The presence of neonatal features was associated with earlier resistance to TSH (P < 0.001) and with the development of neurocognitive impairment (P = 0.02) or constipation (P = 0.04) later in life.
Conclusion
Our findings suggest that iPPSD/PHP and especially iPPSD2/PHP1A newborns require specific care at birth because of an increased risk of neonatal complications. These complications may predict a more severe course of the disease; however, they are unspecific which likely explains the diagnostic delay.
•X-linked hypophosphatemia is the most common cause of inherited hypophosphatemia.•Burosumab: a novel monoclonal antibody that specifically targets FGF23 restores the phosphate renal reabsorption and ...the endogenous calcitriol synthesis panel discussion on the management of young XLH patients treated with burosumab.•Practical clinical points based on the French experience with burosumab.
Hereditary hypophosphatemia with increased FGF23 levels are rare inherited metabolic diseases characterized by low serum phosphate because of impaired renal tubular phosphate reabsorption. The most common form is X-linked hypophosphatemia (XLH), secondary to a mutation in the PHEX gene. In children, XLH is often manifested by rickets, delayed development of gait, lower limb deformities, growth retardation, craniosynostosis, and spontaneous dental abscesses. In adults, patients present diffuse musculoskeletal pain (bone and joints), early osteoarthritis, entesopathies, pseudo-fractures, muscular weakness, and severe dental damage. Conventional medical management is based on the combined administration of oral phosphate supplementation with active vitamin D analogs. Treatment with the recently approved anti-FGF23 burosumab is an alternative, especially in severe forms. Burosumab restores phosphate reabsorption in the proximal tubule and stimulates the endogenous synthesis of calcitriol. In Europe, burosumab has been approved for the treatment of XLH with radiographic evidence of bone disease in pediatric patients from one year of age and in adults. This manuscript will discuss the specific management of burosumab in children and adolescents in daily practice.
Parathormone (PTH) resistance is characterized by hypocalcaemia, hyperphosphatemia, and elevated PTH in the absence of vitamin D deficiency. Pseudohypoparathyroidism type 1A PHP1A, or inactivating ...parathormone (PTH)/PTHrp signaling disorder 2, according to the new classification (iPPSD2), is caused by mutations in the maternal GNAS allele.
To assess PTH resistance over time in 20 patients affected by iPPSD2 (PHP1A), diagnosed because of family history, ectopic ossification, or short stature, and carrying a GNAS mutation.
We gathered retrospective data for calcium, phosphate, thyrotropin (TSH), and PTH levels at regular intervals. PTH infusion testing (teriparatide) was performed in 1 patient.
Patients were diagnosed at a mean age of 3.9 years and had a mean follow-up of 2 years. TSH resistance was already present at diagnosis in all patients (TSH, 13.3 ± 9.0 mIU/L). Over time, PTH levels increased (179 to 306 pg/mL; P < 0.05), and calcium levels decreased (2.31 to 2.21 mmol/L; P < 0.05), but phosphate levels did not decrease with age as expected for healthy individuals. One patient born with ectopic ossifications showed an increase in cyclic adenosine monophosphate upon PTH infusion, similar to that of controls, at 7 months of age, but an impaired response at 4 years of age.
In patients with iPPSD2 (PHP1A), PTH resistance and hypocalcemia develop over time. These findings highlight the importance of screening for maternal GNAS mutations in the presence of ectopic ossifications or family history, even in the absence of PTH resistance and hypocalcemia. The follow-up of these patients should include regular assessments of calcium, phosphate, and PTH levels.
X-linked hypophosphatemia (XLH) is a rare genetic disease that disturbs bone and teeth mineralization. It also affects craniofacial growth and patients with XLH often require orthodontic treatment. ...The aim of this study was to describe changes in the dental health of XLH children during orthodontic treatment compared with those in matched controls undergoing similar orthodontic procedures.
For this retrospective case-control study, we included all individuals less than 16 years old diagnosed with XLH, orthodontically treated in our centre from 2016 to 2022 and pair-matched them to patients with no chronic or genetic conditions. Clinical and radiological parameters concerning their malocclusion, craniofacial discrepancy and the characteristics and iatrogenic effects of their orthodontic treatment were analysed.
Fifteen XLH patients (mean age: 11.3 ± 2.1), pair-matched to 15 control patients were included. Orthodontic treatment was successfully conducted in XLH patients with slightly shorter duration and similar iatrogenic effects as in the control group, except for the occurrence of dental abscess during and after orthodontic tooth movement. XLH patients did not show more relapse than the controls.
Despite the presence of oral manifestations of XLH such as spontaneous abscesses, XLH patients can undergo orthodontic treatment with no obvious additional iatrogenic effects.
Context: Rapid-onset obesity with hypoventilation, hypothalamic, autonomic dysregulation, and neural tumor (ROHHADNET) is a newly described syndrome that can cause cardiorespiratory arrests and ...death. It mimics several endocrine disorders or genetic obesity syndromes during early childhood and is associated with various forms of hypothalamic-pituitary endocrine dysfunctions that have not yet been fully investigated.
Objective: The current report aspires to facilitate the earlier recognition and appropriate treatment of the ROHHADNET syndrome when children present with various endocrine manifestations, such as early obesity, growth failure, pseudo-Cushing’s syndrome, glucocorticoid insufficiency, congenital hypopituitarism, or adrenal tumors. A more widespread knowledge of the syndrome will help characterize its molecular origin.
Design: Endocrine studies were performed in six patients admitted for seemingly common early-onset obesity associated with growth failure in five of them. The six patients later showed distinctive features of the ROHHADNET syndrome.
Results: Abnormalities of the pituitary adrenal axis ranged from a true Cushing-like profile (one of six), to glucocorticoid deficiency with normal ACTH (two of six). Complete GH deficiency with low IGF-I was observed in four of six, hypogonadotropic hypogonadism in four of six, hyperprolactinemia in six of six, and various degrees of TSH/T4 abnormalities in five of five patients. All had increased natremia without diabetes insipidus. Five children had unilateral macroscopic adrenal ganglioneuroma. Two patients died at 8.5 and 12 yr of age.
Conclusions: Various hypothalamic-pituitary endocrine dysfunctions are associated with ROHHADNET, carrying a risk of misdiagnosis until other elements of the syndrome make it more easily recognizable. Given its severity, ROHHADNET syndrome should be considered in all cases of isolated, rapid, and early obesity.
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