Those subjects with rare (MAF < 1% in the normal ALP group) nonsynonymous ALPL variants exhibited lower serum ALP activity, higher serum phosphate concentrations, and lower femoral neck BMD values. However, there were no statistically significant differences in serum ALP, phosphate, or BMD between participants with and without synonymous or common (MAF>1% in the normal ALP group) nonsynonymous variants. Plots show means and 95% confidence intervals, adjusted for age, weight, and clinic site, in the MrOS group selected for low serum ALP (n = 74).