Pathophysiology and genetics of metabolic bone disorders characterized by increased bone turnover.
Bone is the most important supportive tissue in the human body, and in order to maintain its integrity, it is continuously renewed by a process called "remodeling". Paget's disease of bone (PDB), familial expansile osteolysis (FEO), expansile skeletal hyperphosphatasia (ESH), early-onset Paget's disease of bone (EOPDB), and juvenile Paget's disease (JPD) are all metabolic bone disorders characterized by accelerated bone remodeling. Histological studies have shown that bone-resorbing osteoclasts are the primary disease-causing cells in these disorders. In this review, we provide an overview of the clinical differences between diseases with increased bone turnover. Our main focus is on Paget's disease because this is, by far, the most common form of this type of disease. Molecular genetic studies of these disorders have revealed key players in bone remodeling and have provided further insights in signal transduction in osteoclasts. Moreover, a syndromal form of PDB has been characterized in which PDB is associated with inclusion body myopathy and frontotemporal dementia, pointing toward similar biological pathways in osteoclasts, muscle, and brain cells. However, several additional genes underlying conditions with increased bone turnover remain to be identified.
Beyens
Greet
G
Department of Medical Genetics, University and University Hospital of Antwerp, Antwerp, Belgium.
Van Hul
Wim
W
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000251:Adenosine Triphosphatases / Q000235:genetics; D001851:Bone Diseases, Metabolic / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology*; D016723:Bone Remodeling / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics; D006801:Humans; D008954:Models, Biological; D008967:Molecular Biology; D010001:Osteitis Deformans / Q000209:etiology / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D018098:Paramyxovirinae / Q000472:pathogenicity; D053246:Receptor Activator of Nuclear Factor-kappa B / Q000235:genetics; D000071456:Sequestosome-1 Protein; D013577:Syndrome; D000074405:Valosin Containing Protein
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D053246:Receptor Activator of Nuclear Factor-kappa B; C099718:SQSTM1 protein, human; D000071456:Sequestosome-1 Protein; C505686:TNFRSF11A protein, human; D000251:Adenosine Triphosphatases; D000074405:Valosin Containing Protein