HLA-G and chronic obstructive pulmonary disease: In conclusion, the data indicate that unprotected occupational exposure to freon in the present workplace can induce cardiotoxicity, mainly in the form of cardiac arrhythmias, though their role in inducing arterial hypertension and coronary artery diseases is not well established despite significantly elevated serum cholesterol and urinary β2-microglobulin (tubular lesion marker) levels.