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"Autosomal dominant hypophosphatemic rickets"

Ahmad R Ramadan, Said M Shawar, Manal A Alghamdi
BACKGROUND: Fibroblast growth factor-23 (FGF23) is a bone-derived hormone that regulates the homeostasis of phosphate and vitamin D. Three substitutions in the hormone are reported to cause autosomal dominant hypophosphatemic rickets and seven substitutions to cause autosomal recessive hyperphosphatemic familial tumoral calcinosis (HFTC). Both disorders are rare in the general population and occur most often in the Eastern Mediterranean region and Africa. None of the mutations could be identified using standard restriction fragment length polymorphism...
2016: Hormone Research in Pædiatrics
Diana Ovejero, Rachel I Gafni, Michael T Collins
No abstract text is available yet for this article.
May 2016: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
Rafael A Vega, Charles Opalak, Raymond J Harshbarger, Jeffrey A Fearon, Ann M Ritter, John J Collins, Jennifer L Rhodes
OBJECTIVE This study examines a series of patients with hypophosphatemic rickets and craniosynostosis to characterize the clinical course and associated craniofacial anomalies. METHODS A 20-year retrospective review identified patients with hypophosphatemic rickets and secondary craniosynostosis at 3 major craniofacial centers. Parameters examined included sex, age at diagnosis of head shape anomaly, affected sutures, etiology of rickets, presenting symptoms, number and type of surgical interventions, and associated diagnoses...
June 2016: Journal of Neurosurgery. Pediatrics
Keitaro Yokoyama
Autosomal dominant hypophosphatemic rickets(ADHR)is caused by gain-of-function mutations in FGF23 that prevent its proteolytic cleavage. Fibroblast growth factor 23(FGF23)is a hormone that inhibits renal phosphate reabsorption and 1,25-dihydroxyvitamin D biosynthesis. Low iron status plays a role in the pathophysiology of ADHR. Iron deficiency is an environmental trigger that stimulates FGF23 expression and hypophosphatemia in ADHR. It was reported that FGF23 elevation in patients with CKD, who are often iron deficient...
February 2016: Clinical Calcium
Hiroyuki Yamamoto, Bruno Ramos-Molina, Adam N Lick, Matthew Prideaux, Valeria Albornoz, Lynda Bonewald, Iris Lindberg
FGF23 is an O-glycosylated circulating peptide hormone with a critical role in phosphate homeostasis; it is inactivated by cellular proprotein convertases in a pre-release degradative pathway. We have here examined the metabolism of FGF23 in a model bone cell line, IDG-SW3, prior to and following differentiation, as well as in regulated secretory cells. Labeling experiments showed that the majority of (35)S-labeled FGF23 was cleaved to smaller fragments which were constitutively secreted by all cell types. Intact FGF23 was much more efficiently stored in differentiated than in undifferentiated IDG-SW3 cells...
March 2016: Bone
Klaus Kapelari, Julia Köhle, Dieter Kotzot, Wolfgang Högler
CONTEXT: Autosomal dominant hypophosphatemic rickets (ADHR) is the only hereditary disorder of renal phosphate wasting in which patients may regain the ability to conserve phosphate. Low iron status plays a role in the pathophysiology of ADHR. OBJECTIVE: This study reports of a girl with ADHR, iron deficiency, and a paternal history of hypophosphatemic rickets that resolved without treatment. The girl's biochemical phenotype resolved with iron supplementation. SUBJECTS: A 26-month-old girl presented with typical features of hypophosphatemic rickets, short stature (79 cm; -2...
September 2015: Journal of Clinical Endocrinology and Metabolism
Yuichi Takashi, Seiji Fukumoto
Fibroblast growth factor 23 (FGF23) is an essential hormone for phosphate metabolism. It has been shown that intravenous administration of some iron formulations including saccharated ferric oxide induces hypophosphatemic osteomalacia with high FGF23 levels. On the other hand, iron deficiency promotes FGF23 and induces hypophosphatemia in patients with autosomal dominant hypophosphatemic rickets (ADHR). While iron and phosphate metabolism is connected, the detailed mechanism of this connection remains to be clarified...
July 2015: Clinical Calcium
Bracha K Goldsweig, Thomas O Carpenter
Fibroblast growth factor-23 (FGF23) regulates phosphate reabsorption in the kidney and therefore plays an essential role in phosphate balance in humans. There is a host of defects that ultimately lead to excess FGF23 levels and thereby cause renal phosphate wasting and hypophosphatemic rickets. We describe the genetic, pathophysiologic, and clinical aspects of this group of disorders with a focus on X-linked hypophosphatemia (XLH), the best characterized of these abnormalities. We also discuss autosomal dominant hypophosphatemic rickets (ADHR), autosomal recessive hypophosphatemic rickets (ARHR) and tumor-induced osteomalacia (TIO) in addition to other rarer FGF23-mediated conditions...
April 2015: Current Osteoporosis Reports
Carsten A Wagner, Isabel Rubio-Aliaga, Jürg Biber, Nati Hernando
UNLABELLED: Renal control of systemic phosphate homeostasis is critical as evident from inborn and acquired diseases causing renal phosphate wasting. At least three transport proteins are responsible for renal phosphate reabsorption: NAPI-IIa (SLC34A1), NAPI-IIc (SLC34A3) and PIT-2 (SLC20A2). These transporters are highly regulated by various cellular mechanisms and factors including acid-base status, electrolyte balance and hormones such as dopamine, glucocorticoids, growth factors, vitamin D3, parathyroid hormone and fibroblast growth factor 23 (FGF23)...
September 2014: Nephrology, Dialysis, Transplantation
Shoji Ichikawa, Amie K Gray, Leah R Padgett, Matthew R Allen, Erica L Clinkenbeard, Nicole M Sarpa, Kenneth E White, Michael J Econs
Fibroblast growth factor 23 (FGF23) is a hormone that inhibits renal phosphate reabsorption and 1,25-dihydroxyvitamin D biosynthesis. The FGF23 subtilisin-like proprotein convertase recognition sequence ((176)RHTR(179)↓) is protected by O-glycosylation through ppGalNAc-T3 (GALNT3) activity. Thus, inactivating GALNT3 mutations render FGF23 susceptible to proteolysis, thereby reducing circulating intact hormone levels and leading to hyperphosphatemic familial tumoral calcinosis. To further delineate the role of glycosylation in the Fgf23 function, we generated an inducible FGF23 transgenic mouse expressing human mutant FGF23 (R176Q and R179Q) found in patients with autosomal dominant hypophosphatemic rickets (ADHR) and bred this animal to Galnt3 knockout mice, a model of familial tumoral calcinosis...
October 2014: Endocrinology
Myles Wolf, Kenneth E White
PURPOSE OF REVIEW: High levels of fibroblast growth factor 23 (FGF23) cause the rare disorders of hypophosphatemic rickets and are a risk factor for cardiovascular disease and death in patients with chronic kidney disease (CKD). Despite major advances in understanding FGF23 biology, fundamental aspects of FGF23 regulation in health and in CKD remain mostly unknown. RECENT FINDINGS: Autosomal dominant hypophosphatemic rickets (ADHR) is caused by gain-of-function mutations in FGF23 that prevent its proteolytic cleavage, but affected individuals experience a waxing and waning course of phosphate wasting...
July 2014: Current Opinion in Nephrology and Hypertension
Keiichi Ozono, Toshimi Michigami, Noriyuki Namba, Shigeo Nakajima, Takehisa Yamamoto
Serum phosphate levels are regulated in both calcium-dependent and -independent fashions. Active vitamin D increases while PTH decreases serum phosphate levels in association with the elevation of serum calcium. On the other hand, a calcium-independent phosphaturic factor, historically called phosphatonin is believed to exert a physiological function based on findings in hereditary and tumor-induced diseases characterized by hypophosphatemia with normocalcemia. Among them, autosomal dominant hypophosphatemic rickets (ADHR) has contributed greatly to its elucidation because the gene responsible for ADHR encodes fibroblast growth factor 23 (FGF23) that has been found to have a phosphaturic effect...
2006: Clinical Pediatric Endocrinology: Case Reports and Clinical Investigations: Official Journal of the Japanese Society for Pediatric Endocrinology
Erik A Imel, Amie K Gray, Leah R Padgett, Michael J Econs
BACKGROUND: Excess fibroblast growth factor 23 (FGF23) causes hypophosphatemia in autosomal dominant hypophosphatemic rickets (ADHR) and X-linked hypophosphatemia (XLH). Iron status influences C-terminal FGF23 (incorporating fragments plus intact FGF23) in ADHR and healthy subjects, and intact FGF23 in ADHR. We hypothesized that in XLH serum iron would inversely correlate to C-terminal FGF23, but not to intact FGF23, mirroring the relationships in normal controls. METHODS: Subjects included 25 untreated outpatients with XLH at a tertiary medical center and 158 healthy adult controls...
March 2014: Bone
S Tournis, T Koromila, N Chatzistamatas, M Droggaris, C Zafeiris, K Makris, H Marketou, N Papaioannou, P Kollia, S Gazi
No abstract text is available yet for this article.
September 2013: Journal of Musculoskeletal & Neuronal Interactions
Erica L Clinkenbeard, Emily G Farrow, Lelia J Summers, Taryn A Cass, Jessica L Roberts, Christine A Bayt, Tim Lahm, Marjorie Albrecht, Matthew R Allen, Munro Peacock, Kenneth E White
Fibroblast growth factor 23 (FGF23) gain of function mutations can lead to autosomal dominant hypophosphatemic rickets (ADHR) disease onset at birth, or delayed onset following puberty or pregnancy. We previously demonstrated that the combination of iron deficiency and a knock-in R176Q FGF23 mutation in mature mice induced FGF23 expression and hypophosphatemia that paralleled the late-onset ADHR phenotype. Because anemia in pregnancy and in premature infants is common, the goal of this study was to test whether iron deficiency alters phosphate handling in neonatal life...
February 2014: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
Mutsuko Ohnishi, Mohammed S Razzaque
Phosphate is widely distributed in the body and an adequate balance is required for maintaining essential cellular and organ functions. Dysregulation of phosphate balance, either in the form of hypophosphatemia or hyperphosphatemia can induce disorders ranging from rickets/osteomalacia to cardiovascular calcification. A physiologic phosphate balance is delicately maintained by multiorgan cross-talks among the intestine, kidney, and bone. Sodium-dependent phosphate (Na/Pi) cotransporters present in the intestine and kidney play a major role in phosphate absorption and reabsorption, according to the body's demand...
2013: Contributions to Nephrology
Jian Q Feng, Erica L Clinkenbeard, Baozhi Yuan, Kenneth E White, Marc K Drezner
Although recent studies have established that osteocytes function as secretory cells that regulate phosphate metabolism, the biomolecular mechanism(s) underlying these effects remain incompletely defined. However, investigations focusing on the pathogenesis of X-linked hypophosphatemia (XLH), autosomal dominant hypophosphatemic rickets (ADHR), and autosomal recessive hypophosphatemic rickets (ARHR), heritable disorders characterized by abnormal renal phosphate wasting and bone mineralization, have clearly implicated FGF23 as a central factor in osteocytes underlying renal phosphate wasting, documented new molecular pathways regulating FGF23 production, and revealed complementary abnormalities in osteocytes that regulate bone mineralization...
June 2013: Bone
Margaret Seton, Harald Jüppner
BACKGROUND: Autosomal dominant hypophosphatemic rickets (ADHR) is a rare genetic disorder of phosphate homeostasis characterized, when severely expressed, by osteomalacia, suppressed levels of calcitriol, and renal phosphate wasting due to elevated levels of fibroblast growth factor 23 (FGF23). The disease is caused by heterozygous FGF23 mutations at the RXXR site that prevent cleavage of the intact hormone. OBJECTIVES: An FGF23 mutation was identified in the proband an 85-year-old woman with elevated FGF23 levels, and her clinical course was characterized...
February 2013: Bone
Giampiero I Baroncelli, Benedetta Toschi, Silvano Bertelloni
PURPOSE OF REVIEW: Description of the recent advances on the regulation of phosphate metabolism, gene mutations, and new approaches to treatment in patients with hypophosphatemic rickets. RECENT FINDINGS: Fibroblast growth factor 23 (FGF23) overproduction may be a primary cause of hypophosphatemic rickets. Inactivating mutations of phosphate-regulating gene with homologies to endopeptidases on the X chromosome, dentin matrix acidic phosphoprotein 1, and ectonucleotide pyrophosphatase/phosphodiesterase 1 are associated with X-linked hypophosphatemic rickets, autosomal recessive hypophosphatemic rickets 1, and autosomal recessive hypophosphatemic rickets 2, respectively...
December 2012: Current Opinion in Endocrinology, Diabetes, and Obesity
Masahide Mizobuchi, Taihei Suzuki
In the latter 1990s, phosphate, as well as calcium, has been shown to have a direct action on parathyroid function. Since then although many researchers have tried to detect the phosphate sensor in parathyroid gland, none has found it yet. In 2000s, the importance of FGF23 was revealed in patients with autosomal dominant hypophosphatemic rickets and then investigating the role of FGF23 in mineral metabolism has spread. FGF23 target organs comprise those that express coreceptor Klotho, such as kidney and parathyroid glands...
October 2012: Clinical Calcium
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