During a single session, all of the present HD patients exhibited significant increases in arterial levels of AcAc from 26.0 (range 20.0–36.5) μmol/L to 82.0 (39.8–157.8) μmol/L (p < 0.0001) (Fig. 1a) as well as β-HB from 20.0 (14.8–42.0) μmol/L to 104.0 (32.0–297.3) μmol/L (p < 0.0001) (Fig. 1b). The gene discussed is GSTM1; the disease is Huntington disease.