Patients with an abnormal ALT had a higher mean body mass index (BMI) (26.8 kg/m2 vs 24.1 kg/m2; P = .004), higher mean O3 level (38.4 ppb vs 32.9 ppb; P = .02), and a higher proportion of liver cirrhosis (21.7% vs 5.3%; P = .02) (Table 4). This evidence concerns the gene GPT and cirrhosis of liver.