The value below 80% means that the AT III activity decreases.[12] It is reported that the prevalence of AT deficiency in the total population is 1/5000 to 1/500.[13] Patients with AT deficiency have a high risk for a first occurrence and recurrence of VTE.[10] AT deficiency is responsible for congenital gene mutations or acquired factors in clinical scenarios causing low hepatic production, protein consumption or protein loss.[9] Hereditary AT deficiency is an autosomal dominant disease, most of them are heterozygotes. Here, SERPINC1 is linked to autosomal dominant disease.