The total cholesterol (P < 0.047), the PON1 activity (P < 0.001) and ApoA1 levels (P < 0.001) were significantly lower in MCTD patients than in the controls, while there was no difference in apolipoprotein B concentrations between patients with MCTD and controls (P = 0.693). Here, PON1 is linked to mixed connective tissue disease.