RESUMO
Hypophosphatemia is a genetically heterogeneous disease. Here, we mapped an autosomal recessive form (designated ARHP) to chromosome 4q21 and identified homozygous mutations in DMP1 (dentin matrix protein 1), which encodes a non-collagenous bone matrix protein expressed in osteoblasts and osteocytes. Intact plasma levels of the phosphaturic protein FGF23 were clearly elevated in two of four affected individuals, providing a possible explanation for the phosphaturia and inappropriately normal 1,25(OH)2D levels and suggesting that DMP1 may regulate FGF23 expression.
Assuntos
Matriz Óssea/metabolismo , Proteínas da Matriz Extracelular/genética , Hipofosfatemia/genética , Fosfatos/metabolismo , Fosfoproteínas/genética , Adolescente , Adulto , Criança , Proteínas da Matriz Extracelular/metabolismo , Proteínas da Matriz Extracelular/fisiologia , Fator de Crescimento de Fibroblastos 23 , Fatores de Crescimento de Fibroblastos/genética , Fatores de Crescimento de Fibroblastos/metabolismo , Homeostase , Humanos , Lactente , Mutação , Endopeptidase Neutra Reguladora de Fosfato PHEX/genética , Endopeptidase Neutra Reguladora de Fosfato PHEX/metabolismo , Linhagem , Fosfoproteínas/metabolismo , Fosfoproteínas/fisiologiaRESUMO
OBJECTIVE: To outline the efficacy and risks of bisphosphonate therapy for the management of osteoporosis and describe which patients might be eligible for bisphosphonate "drug holiday." QUALITY OF EVIDENCE: MEDLINE (PubMed, through December 31, 2012) was used to identify relevant publications for inclusion. Most of the evidence cited is level II evidence (non-randomized, cohort, and other comparisons trials). MAIN MESSAGE: The antifracture efficacy of approved first-line bisphosphonates has been proven in randomized controlled clinical trials. However, with more extensive and prolonged clinical use of bisphosphonates, associations have been reported between their administration and the occurrence of rare, but serious, adverse events. Osteonecrosis of the jaw and atypical subtrochanteric and diaphyseal femur fractures might be related to the use of bisphosphonates in osteoporosis, but they are exceedingly rare and they often occur with other comorbidities or concomitant medication use. Drug holidays should only be considered in low-risk patients and in select patients at moderate risk of fracture after 3 to 5 years of therapy. CONCLUSION: When bisphosphonates are prescribed to patients at high risk of fracture, their antifracture benefits considerably outweigh their potential for harm. For patients taking bisphosphonates for 3 to 5 years, reassess the need for ongoing therapy.