GENETICS OF BONE LOSS AT THE HIP IN WOMEN

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Heritability of bone mass at the hip is high, but heritability of bone loss at the hip has not been studied. Heritability of bone strength has been measured in 760 pairs of sisters, and a 10cM genome screen has identified several chromosomal loci influencing strength. The hypotheses that will be tested is that the rate of bone loss at the hip in women is genetically determined. This will be achieved by remeasuring hip bone mass in 500 pairs of sisters that had participated in the GCRC Protocol 578 a minimum of 5 years ago. Using the Lunar DPX-L dual X-ray absorptiometry (DXA) the following sites will be measured: the right femoral neck, trochanter and wards, lumbar vertebrae L2 to L4 and total body. Radiographs of the lower pelvis with upper femura in 15 degree internal rotation will be taken on standard X-ray equipment. All structural measurements will be made on the same hip using a digital caliper. Volumetric Quantitative Computed Tomograph (CT) will be performed according to an established protocol. Fasting blood and urine will be collected for measurement of calcium regulating hormones and bone turnover markers. Anthropometrics will be collected on dedicated instruments, total body lean and fat are measured by DXA. Questionnaires will be administered which include personal, family and medical history, gynecological history, medication history, smoking, physical activity and diet. All questionnaires have been verified and have been in use over the last five years in the current sister study.