In sensitivity analyses, removal of the five subjects with NT-proBNP concentrations greater than 400 pg/mL (indicating potential heart failure) did not substantially change the association between NT-proBNP and total GM (β = −3.37; p = 0.0061 when >400 pg/mL values removed versus β = −3.44; p = 0.003 in Model 2). The gene discussed is NPPB; the disease is heart failure.