Genetic background of osteoporosis

Osteoporosis is a systemic disorder of decreased skeletal mass as measured by bone mineral density (BMD), and disturbed skeletal architecture and func tion which results in an increased risk for bone fractures with consecutive ly increased morbidity and mortality. Twin and family studies have shown an important genetic component of BMD of about 40-60 %. This exceeds other we ll known factors influencing BMD such as environmental factors like dietary calcium, physical activity or several drugs and diseases. Therefore, inter est increased in the genetic background of bone mineral density. Polymorphi sms of the Vitamin D receptor gene were the first to be published in this a rea. Studies on other loci or candidate genes such as the estrogen receptor gene or the collagen type I alpha 1 gene also showed associations with bon e mineral density that could explain at least a part of the genetic backgro und of osteoporosis. Recently published data suggest that these genetic mar kers of bone metabolism are important in interaction with each other or in certain bone-affecting diseases. In the future, genetic studies on osteopor osis will have to screen further relevant genes and markers for bone metabo lism as well as to evaluate the complex interactions of genetic influences, so that it would be possible to calculate a patient's individual risk for osteoporosis in the context of environmental influences.