BACKGROUND: Various genetic markers have been identified as influencing bone mineral density (BMD). In a prior study in the UK Biobank, 22,866 SNPs were selected using LASSO based on ability to predict calcaneal bone mineral density. Kim in PLoS ONE 2018 tested this genetic risk score against other models and found it to have the best correlation with BMD.
PURPOSE: Given the prevalence of low BMD and low energy availability in female and male endurance runners, this study investigated the correlation between this genetic risk score and BMD of runners at the Western States endurance race.
METHODS: 51 runners at a 100-mile race underwent a genetic evaluation using an Affymetrix PMRA array including approximately 800,000 SNPs, which includes all those required for the Kim BMD genetic risk score. These runners also underwent dual-energy x-ray absorptiometry. We calculated Pearson’s correlation coefficients between the genetic risk score and spine, hip, femoral, and forearm BMD.
RESULTS: 17 female and 34 male participants had a mean age, respectively, of 41.8 and 46.8 years (range 26.4-76.2). BMI ranged from 17.2-25.2 kg/m
2 (female) and 19.3-39.4 kg/m
2 (male). For the male runners, the genetic risk score significantly correlated with z-scores of the lumbar spine, total hip, femoral neck, forearm, and total body (r=0.52-0.58, p<0.005). For female athletes, all correlations were 0 or negative and non-significant (r=0.0 to -0.30, p=0.24-0.99). See Table 1.
CONCLUSIONS: The BMD genetic risk score was significantly correlated with BMD in the male, but not female ultramarathon runners in this study. The sample size for women (n=17) is too small to draw robust conclusions, but we speculate that for female athletes, environmental and hormonal factors, such as low energy availability or menstrual irregularities, may decrease the influence of genetic factors.
Correlation Between Genetic Risk Score and Bone Mineral Density | Spine Z-Score R, p-value | Total Hip Z-Score R, p-value | Femoral Neck Z-Score R, p-value | Forearm Z-Score R, p-value | Total Body Z-Score R, p-value |
| Women: Genetic Risk Score | 0, 0.99 | -0.16, 0.53 | -0.06, 0.83 | -0.3, 0.24 | -0.11, 0.68 |
| Men: Genetic Risk Score | 0.52, 0.0016 | 0.64, <.0001 | 0.53, 0.0013 | 0.58, 0.0003 | 0.58, 0.0003 |
