Genome-wide linkage scan for quantitative trait loci underlying normal variation in heel bone ultrasound measures.

Quantitative ultrasound (QUS) traits are correlated with bone mineral density (BMD), but predict risk for future fracture independent of BMD. Only a few studies, however, have sought to identify specific genes influencing calcaneal QUS measures. The aim of this study was to conduct a genome-wide linkage scan to identify quantitative trait loci (QTL) influencing normal variation in QUS traits. QUS measures were collected from a total of 719 individuals (336 males and 383 females) from the Fels Longitudinal Study who have been genotyped and have at least one set of QUS measurements. Participants ranged in age from 18.0 to 96.6 years and were distributed across 110 nuclear and extended families. Using the Sahara ® bone sonometer, broadband ultrasound attenuation (BUA), speed of sound (SOS) and stiffness index (QUI) were collected from the right heel. Variance components based linkage analysis was performed on the three traits using 400 polymorphic short tandem repeat (STR) markers spaced approximately 10 cM apart across the autosomes to identify QTL influencing the QUS traits. Age, sex, and other significant covariates were simultaneously adjusted. Heritability estimates (h²) for the QUS traits ranged from 0.42 to 0.57. Significant evidence for a QTL influencing BUA was found on chromosome 11p15 near marker D11S902 (LOD = 3.11). Our results provide additional evidence for a QTL on chromosome 11p that harbors a potential candidate gene(s) related to BUA and bone metabolism.

Longitudinal changes in calcaneal quantitative ultrasound measures during childhood.

UNLABELLED: This longitudinal study examined how calcaneal quantitative ultrasound (QUS) measures change during childhood while taking into account skeletal maturation, body mass index (BMI), and physical activity. The study reported sex differences in QUS growth curves and an inverse relationship between BMI and speed of sound (SOS) measures. INTRODUCTION: The aim of this study was to examine how calcaneal QUS parameters change over time during childhood and to determine what factors influence these changes. METHODS: The study sample consisted of a total of 192 Caucasian children participating in the Fels Longitudinal Study. A total of 548 calcaneal broadband ultrasound attenuation (BUA) and SOS observations were obtained between the ages of 7.6 and 18 years. The best fitting growth curves were determined using statistical methods for linear mixed effect models. RESULTS: There are significant sex differences in the pattern of change in QUS parameters (p < 0.05). The relationship between QUS measures and skeletal age is best described by a cubic growth curve in boys and a linear pattern among girls. Boys experience their most rapid growth in BUA and SOS in early and late adolescence, while girls experience constant growth throughout childhood. Adiposity levels were significantly associated with the changes in SOS among boys (p < 0.001) and girls (p < 0.01), indicating that children with higher BMI are likely to have lower SOS over time compared to children with lower BMI. For girls, physical activity levels showed positive associations with changes in QUS measures (p < 0.05). CONCLUSION: This study documents significant sex differences in the pattern of change in QUS measures over childhood and adolescence. Our study also shows significant influences of adiposity and physical activity on the pattern of change in QUS measures during childhood.

Sleep disturbance in relation to health-related quality of life in adults: the Fels Longitudinal Study.

OBJECTIVE: Sleep disturbances are prevalent problems in the general population. Symptoms of insomnia can impact various physical and mental conditions. Furthermore, sleep disturbances may worsen the quality of life independently of co-occurring medical conditions. In this study, we examined the relationships between self-reported sleep disturbance symptoms and health-related quality of life measures in the Fels Longitudinal Study. DESIGN: Cross-sectional study. PARTICIPANTS: A total of 397 adults (175 men and 222 women) aged 40 years and older were included in the present study. MEASUREMENTS: Three self-reported sleep disturbance measures (difficulty falling asleep, nocturnal awakenings and maintaining sleep, and daytime tiredness) were collected between 2003 and 2006. Health-related quality of life measures were assessed using the Medical Outcomes Survey Short Form (SF)-36. Socio-demographic status (marital status, employment status, and education) and current medical conditions were collected from participants during study visits. RESULTS: Individuals who reported frequent sleep disturbances showed significantly worse quality of life on all SF-36 subscales examined. The odds ratio (OR) ranged from 1.71 to 18.32 based on symptoms of insomnia across seven SF-36 domains in analyses adjusted for significant covariates influencing quality of life. Participants with severe sleep disturbances (both sleep problems and daytime impairment) showed generally higher odds of reporting poor SF-36 scores (adjusted ORs; 5.88 - 17.09) compared to participants with no problems. CONCLUSION: Sleep disturbance is comprehensively and independently associated with poor health-related quality of life in middle-aged and older adults.