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Khanjee N, Maalouf NM. Romosozumab-aqqg in the Treatment of Osteoporosis in a Patient With Hypophosphatasia. J Endocr Soc 2022; 6:bvac159. [DOI: 10.1210/jendso/bvac159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Indexed: 11/11/2022] Open
Abstract
Abstract
Hypophosphatasia is a rare, inherited condition that causes osteomalacia and recurrent fractures. Therapeutic options for osteoporosis in patients with hypophosphatasia are limited because of concerns for a greater likelihood of atypical femoral fractures with antiresorptive agents. We report here the case of a patient with hypophosphatasia and osteoporosis who was treated with romosozumab-aqqg (Romo). An 81-year-old woman presented for management of osteoporosis with multiple fractures. She experienced a decline in bone mineral density over 20 years despite sequential osteoporosis treatment with oral bisphosphonates, hormone replacement therapy, teriparatide, and denosumab. Hypophosphatasia was suspected because of low serum alkaline phosphatase levels and was confirmed by genetic testing. After diagnosing hypophosphatasia, bone mineral density continued to decline and a trial of Romo was begun. After 1 year of Romo therapy, bone mineral density improved by 21%, and 10% at the lumbar spine and total hip, respectively. These changes were substantially greater than what she had experienced with prior teriparatide therapy. Blood alkaline phosphatase remained low on Romo. To our knowledge, this is the first report of a patient with hypophosphatasia and osteoporosis treated with Romo. In our patient, Romo did not significantly impact serum alkaline phosphatase, but improved bone mineral density significantly. In conclusion, Romo is a potential treatment option for osteoporosis in patients with hypophosphatasia for whom limited alternatives exist.
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Affiliation(s)
- Naveed Khanjee
- Department of Internal Medicine, Division of Endocrinology, University of Texas Southwestern Medical Center , Dallas, TX 75390-8885 , USA
| | - Naim M Maalouf
- Department of Internal Medicine, Division of Endocrinology, University of Texas Southwestern Medical Center , Dallas, TX 75390-8885 , USA
- The Charles and Jane Pak Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center , Dallas, TX 75390-8885 , USA
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Michałus I, Gawlik A, Wieczorek-Szukała K, Lewiński A. The Clinical Picture of Patients Suffering from Hypophosphatasia—A Rare Metabolic Disease of Many Faces. Diagnostics (Basel) 2022; 12:diagnostics12040865. [PMID: 35453912 PMCID: PMC9031194 DOI: 10.3390/diagnostics12040865] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Revised: 03/22/2022] [Accepted: 03/29/2022] [Indexed: 11/16/2022] Open
Abstract
Hypophosphatasia (HPP) is a rare, and usually diagnosed with delay, genetic disease caused by a mutation in the alkaline phosphatase liver/bone/kidney type (ALPL) gene. Low activity of the alkaline phosphatase (ALP) impairs the hydroxyapatite formation, reducing skeletal mineralization. The aim of the study was to present patients diagnosed with HPP. The data from the history and medical records of patients were analyzed. In the study group, one patient was diagnosed with perinatal type of HPP, three were diagnosed with infant variant, eight were diagnosed with children variant, two were diagnosed with odontohypophosphatasia, and two were diagnosed with the adult type of the disease. The most frequently presented symptoms included premature loss of teeth in 11/16 (68.75%) patients, bone deformities in 10/16 (62.5%) patients, chronic bone pain in 9/16 (56.25%) patients, and fractures in 8/16 (50%) patients. Reduction in bone mineral density in at least one examined projection has been found in 11/14 patients. Conclusions: The correct diagnosis of HPP is difficult due to the variety of types and clinical symptoms, as well as the very rare occurrence of this disease. Both lower and upper reference values of the determined biochemical parameters may be important in HPP diagnostics.
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Affiliation(s)
- Izabela Michałus
- Department of Endocrinology and Metabolic Diseases, Polish Mother’s Memorial Hospital-Research Institute, 93-338 Lodz, Poland;
| | - Aneta Gawlik
- Department of Pediatrics and Pediatric Endocrinology, Faculty of Medical Sciences, Medical University of Silesia, 40-759 Katowice, Poland;
| | | | - Andrzej Lewiński
- Department of Endocrinology and Metabolic Diseases, Polish Mother’s Memorial Hospital-Research Institute, 93-338 Lodz, Poland;
- Department of Endocrinology and Metabolic Diseases, Medical University of Lodz, 90-419 Lodz, Poland;
- Correspondence:
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Garcia-Giralt N, Roca-Ayats N, Abril JF, Martinez-Gil N, Ovejero D, Castañeda S, Nogues X, Grinberg D, Balcells S, Rabionet R. Gene Network of Susceptibility to Atypical Femoral Fractures Related to Bisphosphonate Treatment. Genes (Basel) 2022; 13:genes13010146. [PMID: 35052486 PMCID: PMC8774942 DOI: 10.3390/genes13010146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/12/2022] [Accepted: 01/13/2022] [Indexed: 02/01/2023] Open
Abstract
Atypical femoral fractures (AFF) are rare fragility fractures in the subtrocantheric or diaphysis femoral region associated with long-term bisphosphonate (BP) treatment. The etiology of AFF is still unclear even though a genetic basis is suggested. We performed whole exome sequencing (WES) analysis of 12 patients receiving BPs for at least 5 years who sustained AFFs and 4 controls, also long-term treated with BPs but without any fracture. After filtration and prioritization of rare variants predicted to be damaging and present in genes shared among at least two patients, a total of 272 variants in 132 genes were identified. Twelve of these genes were known to be involved in bone metabolism and/or AFF, highlighting DAAM2 and LRP5, both involved in the Wnt pathway, as the most representative. Afterwards, we intersected all mutated genes with a list of 34 genes obtained from a previous study of three sisters with BP-related AFF, identifying nine genes. One of these (MEX3D) harbored damaging variants in two AFF patients from the present study and one shared among the three sisters. Gene interaction analysis using the AFFNET web suggested a complex network among bone-related genes as well as with other mutated genes. BinGO biological function analysis highlighted cytoskeleton and cilium organization. In conclusion, several genes and their interactions could provide genetic susceptibility to AFF, that along with BPs treatment and in some cases with glucocorticoids may trigger this so feared complication.
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Affiliation(s)
- Natalia Garcia-Giralt
- Musculoskeletal Research Group, IMIM (Hospital del Mar Medical Research Institute), Centro de Investigación Biomédica en Red en Fragilidad y Envejecimiento Saludable (CIBERFES), ISCIII, 08003 Barcelona, Spain; (D.O.); (X.N.)
- Correspondence:
| | - Neus Roca-Ayats
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, 08028 Barcelona, Spain; (N.R.-A.); (J.F.A.); (N.M.-G.); (D.G.); (S.B.); (R.R.)
| | - Josep F Abril
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, 08028 Barcelona, Spain; (N.R.-A.); (J.F.A.); (N.M.-G.); (D.G.); (S.B.); (R.R.)
| | - Nuria Martinez-Gil
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, 08028 Barcelona, Spain; (N.R.-A.); (J.F.A.); (N.M.-G.); (D.G.); (S.B.); (R.R.)
| | - Diana Ovejero
- Musculoskeletal Research Group, IMIM (Hospital del Mar Medical Research Institute), Centro de Investigación Biomédica en Red en Fragilidad y Envejecimiento Saludable (CIBERFES), ISCIII, 08003 Barcelona, Spain; (D.O.); (X.N.)
| | - Santos Castañeda
- Department of Rheumatology, Hospital Universitario de La Princesa, IIS-Princesa, Cátedra UAM-Roche, EPID-Future, Universidad Autónoma de Madrid, 28670 Madrid, Spain;
| | - Xavier Nogues
- Musculoskeletal Research Group, IMIM (Hospital del Mar Medical Research Institute), Centro de Investigación Biomédica en Red en Fragilidad y Envejecimiento Saludable (CIBERFES), ISCIII, 08003 Barcelona, Spain; (D.O.); (X.N.)
| | - Daniel Grinberg
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, 08028 Barcelona, Spain; (N.R.-A.); (J.F.A.); (N.M.-G.); (D.G.); (S.B.); (R.R.)
| | - Susanna Balcells
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, 08028 Barcelona, Spain; (N.R.-A.); (J.F.A.); (N.M.-G.); (D.G.); (S.B.); (R.R.)
| | - Raquel Rabionet
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, Universitat de Barcelona, CIBERER, IBUB, IRSJD, 08028 Barcelona, Spain; (N.R.-A.); (J.F.A.); (N.M.-G.); (D.G.); (S.B.); (R.R.)
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Warren AM, Ebeling PR, Grill V, Seeman E, Sztal-Mazer S. Bilateral atypical femoral fractures during denosumab therapy in a patient with adult-onset hypophosphatasia. Endocrinol Diabetes Metab Case Rep 2021; 2021:EDM210096. [PMID: 34515659 PMCID: PMC8495717 DOI: 10.1530/edm-21-0096] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 08/19/2021] [Indexed: 11/25/2022] Open
Abstract
SUMMARY Hypophosphatasia (HPP) is a rare and under-recognised genetic defect in bone mineralisation. Patients presenting with fragility fractures may be mistakenly diagnosed as having osteoporosis and prescribed antiresorptive therapy, a treatment which may increase fracture risk. Adult-onset HPPhypophosphatasia was identified in a 40-year-old woman who presented with bilateral atypical femoral fractures after 4 years of denosumab therapy. A low serum alkaline phosphatase (ALP) and increased serum vitamin B6 level signalled the diagnosis, which was later confirmed by identification of two recessive mutations of the ALPL gene. The patient was treated with teriparatide given the unavailability of ALP enzyme-replacement therapy (asfotase alfa). Fracture healing occurred, but impaired mobility persisted. HPP predisposes to atypical femoral fracture (AFF) during antiresorptive therapy; hence, bisphosphonates and denosumab are contraindicated in this condition. Screening patients with fracture or 'osteoporosis' to identify a low ALP level is recommended. LEARNING POINTS Hypophosphatasia (HPP) is a rare and under-recognised cause of bone fragility produced by impaired matrix mineralisation that can be misdiagnosed as a fragility fracture due to age-related bone loss. Antiresorptive therapy is contraindicated in HPP. Low serum alkaline phosphatase (ALP) provides a clue to the diagnosis. Elevated serum vitamin B6 (an ALP substrate) is indicative of HPP, while identification of a mutation in the ALPL gene is confirmatory. Enzyme therapy with recombinant ALP (asfotase alfa) is currently prohibitively costly. Treatment with anabolic bone agents such as teriparatide has been reported, but whether normally mineralized bone is formed requires further study.
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Affiliation(s)
- Annabelle M Warren
- Department of Endocrinology, The Alfred Hospital, Melbourne, Victoria, Australia
- Department of Endocrinology, The Austin Hospital, Heidelberg, Victoria, Australia
- Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Peter R Ebeling
- Department of Medicine, School of Clinical Sciences, Monash University, Clayton, Victoria, Australia
- Department of Endocrinology, Monash Health, Clayton, Victoria, Australia
| | - Vivian Grill
- Department of Endocrinology, Western Health, St Alban’s, Victoria, Australia
- Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Ego Seeman
- Department of Endocrinology, The Austin Hospital, Heidelberg, Victoria, Australia
- Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Shoshana Sztal-Mazer
- Department of Endocrinology, The Alfred Hospital, Melbourne, Victoria, Australia
- Women’s Health Research Program, School of Public Health and Preventative Medicine, Monash University, Melbourne, Victoria, Australia
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Hepp N, Frederiksen AL, Duno M, Præst Holm J, Rye Jørgensen N, Beck Jensen JE. Biochemical, clinical and genetic characteristics in adults with persistent hypophosphatasaemia; Data from an endocrinological outpatient clinic in Denmark. Bone Rep 2021; 15:101101. [PMID: 34258332 PMCID: PMC8256181 DOI: 10.1016/j.bonr.2021.101101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/18/2021] [Accepted: 06/23/2021] [Indexed: 12/18/2022] Open
Abstract
Background Hypophosphatasia (HPP) is an inborn disease caused by pathogenic variants in ALPL. Low levels of alkaline phosphatase (ALP) are a biochemical hallmark of the disease. Scarce knowledge about the prevalence of HPP in Scandinavia exists, and the variable clinical presentations make diagnostics challenging. The aim of this study was to investigate the prevalence of ALPL variants as well as the clinical and biochemical features among adults with endocrinological diagnoses and persistent hypophosphatasaemia. Methods A biochemical database containing ALP measurements of 26,121 individuals was reviewed to identify adults above 18 years of age with persistently low levels of ALP beneath range (≤ 35 ± 2.7 U/L). ALPL genetic testing, biochemical evaluations and assessment of clinical features by a systematic questionnaire among included patients, were performed. Results Among 24 participants, thirteen subjects (54.2%) revealed a disease-causing variant in ALPL and reported mild clinical features of HPP, of which musculoskeletal pain was the most frequently reported (n = 9). The variant c. 571G > A; p.(Glu191Lys) was identified in six subjects, and an unreported missense variant (c.1019A > C; p.(His340Pro)) as well as a deletion of exon 2 were detected by genetic screening. Biochemical analyses showed no significant differences in ALP (p = 0.059), the bone specific alkaline phosphatase (BALP) (p = 0.056) and pyridoxal-5′-phosphate (PLP) (p = 0.085) between patients with an ALPL variant and negative genetic screening. Patients with a variant in ALPL had significantly higher PLP levels than healthy controls (p = 0.002). We observed normal ALP activity in some patients classified as mild HPP, and slightly increased levels of PLP in two subjects with normal genetic screening and four healthy controls. Among 51 patients with persistent hypophosphatasaemia, fifteen subjects (29.4%) received antiresorptive treatment. Two patients with unrecognized HPP were treated with bisphosphonates and did not show complications due to the treatment. Conclusions Pathogenic variants in ALPL are common among patients with endocrinological diagnoses and low ALP. Regarding diagnostics, genetic testing is necessary to identify mild HPP due to fluctuating biochemical findings. Antiresorptive treatment is a frequent reason for hypophosphatasaemia and effects of these agents in adults with a variant in ALPL and osteoporosis remain unclear and require further studies. Mild HPP is overlooked among adults with endocrinological diagnoses. Biochemical hallmarks of HPP can fluctuate to normal among mild forms. Genetic screening of ALPL including MLPA is necessary to identify mild HPP. Musculoskeletal pain is the most common symptom in adult HPP. Effects of bisphosphonates in mild HPP need further studies.
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Affiliation(s)
- Nicola Hepp
- Dept. of Endocrinology, Hvidovre University Hospital Copenhagen, Kettegaard Alle 30, 2650 Hvidovre, Denmark
| | - Anja Lisbeth Frederiksen
- Dept. of Clinical Genetics, Aalborg University Hospital, Ladegaardsgade 5, 9000 Aalborg C, Denmark.,Dept. of Clinical Research, Aalborg University, Fredrik Bajers Vej 7K, 9220 Aalborg Ø, Denmark
| | - Morten Duno
- Dept. of Clinical Genetics, University Hospital Copenhagen Rigshospitalet, Blegdamsvej 9, 2100 Copenhagen, Denmark
| | - Jakob Præst Holm
- Department of Endocrinology, Copenhagen University Hospital Herlev, Borgmester Ib Juuls Vej 1, 2730 Herlev, Denmark
| | - Niklas Rye Jørgensen
- Dept. of Clinical Biochemistry, Rigshospitalet, Valdemar Hansens Vej 13, 2600 Glostrup, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3 B, 2200 Copenhagen, Denmark
| | - Jens-Erik Beck Jensen
- Dept. of Endocrinology, Hvidovre University Hospital Copenhagen, Kettegaard Alle 30, 2650 Hvidovre, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3 B, 2200 Copenhagen, Denmark
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Nepal S, Jarusriwanna A, Unnanuntana A. Stress Fracture of the Femoral Shaft in Paget's Disease of Bone: A Case Report. J Bone Metab 2021; 28:171-178. [PMID: 34130369 PMCID: PMC8206614 DOI: 10.11005/jbm.2021.28.2.171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 04/19/2021] [Indexed: 11/12/2022] Open
Abstract
Paget’s disease of bone (PDB) is a progressive bone disorder characterized by increased osteoclast-mediated bone resorption and abnormal bone formation. Incomplete atypical femoral fracture, appearing radiographically as a stress fracture at the lateral aspect of the femur, is an uncommon low-trauma fracture frequently seen in association with long-term bisphosphonate therapy. We describe the case of a 61-year-old female patient with PDB who developed a stress fracture at the lateral femoral cortex after 5 doses of intravenous bisphosphonate. The conservative treatment plan included discontinuation of bisphosphonate, a continuation of calcium and vitamin D supplementation, and limited weight-bearing for 3 months. The patient’s pain level gradually improved after switching to the new treatment plan. At the latest follow-up, approximately 5 years after the initiation of conservative treatment, the patient remained pain-free, and her PDB was well-controlled. However, the fracture line was still visible on the most recent radiograph. Although it remains unclear whether a stress fracture at the lateral femoral cortex occurred due to bisphosphonate therapy or PDB, this case highlights the importance of careful evaluation of any lesion that appears in PDB patients receiving bisphosphonate therapy.
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Affiliation(s)
- Sarthak Nepal
- Department of Orthopaedic Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Atthakorn Jarusriwanna
- Department of Orthopaedics, Faculty of Medicine, Naresuan University, Phitsanulok, Thailand
| | - Aasis Unnanuntana
- Department of Orthopaedic Surgery, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
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Rassie K, Dray M, Michigami T, Cundy T. Bisphosphonate Use and Fractures in Adults with Hypophosphatasia. JBMR Plus 2019; 3:e10223. [PMID: 31687651 PMCID: PMC6820463 DOI: 10.1002/jbm4.10223] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 06/24/2019] [Accepted: 07/15/2019] [Indexed: 02/06/2023] Open
Abstract
Adults with hypophosphatasia (HPP) may suffer femoral fractures resembling the atypical femoral fractures that can occur with long‐term bisphosphonate treatment, and there is an emerging consensus that bisphosphonates should not be used in adults with HPP and low bone mass. However, the spectrum of HPP in adults is wide: ranging from the severely affected—who commonly have osteomalacia—through to the minimally affected. The former typically have biallelic and the latter, heterozygous ALPL mutations. We have reviewed reports of fractures in adults with genetically proven HPP which suggest that the risk of fracture is at least 200‐fold greater in those with biallelic mutations. We also discuss two cases of postmenopausal women with heterozygous ALPL mutations. One had fractures and severe osteoporosis, but histology revealed no evidence of osteomalacia. The second had taken alendronate for 8 years, but despite profound suppression of bone turnover, histology again revealed no evidence of osteomalacia. The management of adults with HPP who have coexisting osteoporosis is challenging. More data are clearly needed, but we suggest that the risks of bisphosphonate therapy may be relatively low in patients who have heterozygous mutations and no histological evidence of osteomalacia. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Kate Rassie
- Department of Endocrinology Greenlane Clinical Centre Auckland New Zealand
| | - Michael Dray
- Department of Pathology Waikato Hospital Hamilton New Zealand
| | - Toshimi Michigami
- Department of Bone & Mineral Research Osaka Women's & Children's Hospital Isumi Japan
| | - Tim Cundy
- Department of Endocrinology Greenlane Clinical Centre Auckland New Zealand.,Department of Medicine, Faculty of Medical & Health Sciences University of Auckland Auckland New Zealand
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Choida V, Bubbear JS. Update on the management of hypophosphatasia. Ther Adv Musculoskelet Dis 2019; 11:1759720X19863997. [PMID: 31413732 PMCID: PMC6676257 DOI: 10.1177/1759720x19863997] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 06/22/2019] [Indexed: 12/13/2022] Open
Abstract
Hypophosphatasia is a rare inherited disease caused by a loss of function mutations in the gene that codes for the tissue-nonspecific alkaline phosphatase enzyme. It is autosomally inherited and at least 388 different genetic defects have been identified. The clinical presentation is variable from a severe perinatal form, that is fatal if untreated, to adult-onset disease. This review covers the pathophysiology, diagnosis and current management option including the recently licensed enzyme replacement therapy asfotase alfa.
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Affiliation(s)
- V Choida
- Metabolic Unit, Royal National Orthopaedic Hospital, Stanmore, UK
| | - J S Bubbear
- Metabolic Unit, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, HA7 4LP, UK
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Genest F, Seefried L. Subtrochanteric and diaphyseal femoral fractures in hypophosphatasia-not atypical at all. Osteoporos Int 2018; 29:1815-1825. [PMID: 29774402 DOI: 10.1007/s00198-018-4552-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 04/25/2018] [Indexed: 12/18/2022]
Abstract
UNLABELLED Risk for subtrochanteric and diaphyseal femoral fractures is considered increased in patients with hypophosphatasia (HPP). Evaluating a large cohort of HPP patients, we could for the first time quantify the prevalcence and identify both morphometric features as well as predisposing factors for this complication of severe HPP. INTRODUCTION Subtrochanteric and diaphyseal femoral fractures have been associated with both, long-term antiresorptive treatment and metabolic bone disorders, specifically Hypophosphatasia (HPP). Building on a cross-sectional evaluation of real-world data, this study reports risk factors, prevalence, treatment outcome and morphometric particularities for such fractures in HPP as compared to Atypical Femoral Fractures (AFF) in long-term antiresorptive treatment. METHODS For 15 out of 150 HPP patients identified with having experienced at least one such fracture, medical records were reviewed in detail, extracting medical history, genotype, lab assessments, bone mineral density (DXA), radiographic data on femoral geometry and clinical aspects of fracture etiology and healing. RESULTS Bilateral fractures were documented in 10 of these 15 patients, yielding a total of 25 fractures for evaluation. Disease-inherent risk factors included autosomal-recessive, childhood onset HPP, apparently low alkaline phosphatase (ALP) ≤ 20 U/l and substantially elevated pyridoxal 5'-phosphate (PLP) > 3 times upper limit of normal as well as high lumbar spine BMD. Fracture morphology met definition criteria for AFF in 88% of cases. Femoral geometry revealed additional risk factors previously described for AFF, including decreased femoral neck-shaft angle and increased femoral offset. Extrinsic risk factors include Hypovitaminosis D (80%) and pre-treatment with bisphosphonates (46,7%) and Proton-Pump Inhibitors (40%). CONCLUSIONS Increased risk for subtrochanteric and diaphyseal femoral fractures in HPP appears to result from both compromised bone metabolism as well as disease-associated bone deformities. In severe HPP, generous screening for such fractures seems advisable. Bisphosphonates and Hypovitaminosis D should be avoided. Healing is compromised and requires mindful consideration of both pharmacological and surgical options.
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Affiliation(s)
- F Genest
- Clinical Trial Unit, Orthopedic Department, University of Wuerzburg, Brettreichstrasse 11, 97074, Wuerzburg, Germany
| | - L Seefried
- Clinical Trial Unit, Orthopedic Department, University of Wuerzburg, Brettreichstrasse 11, 97074, Wuerzburg, Germany.
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