Abstract 1921: Clinical Impact of Heterozygous Carrier of Autosomal Recessive Hypercholesterolemia on Asymptomatic Hyperlipidemic Patients: Evidence From Familial Gene Analysis
Autosomal recessive hypercholesterolemia (ARH) is an extremely rare genetic defect, and is recognized only around 50 cases in all over the world. The genetic cause of ARH is mutation in an adaptor protein involved in low-density lipoprotein (LDL) receptor internalization, which results in marked elevation of serum LDL cholesterol (LDL-C) and premature atherosclerosis. Therefore, few data exist regarding the clinical significance about the heterozygous carrier of ARH. We recently identified the second ARH patient (Ins C599) in Japan and his some relatives who have the same single mutation (heterozygous). We identified 11 heterozygous ARH carriers (male=5, mean age=48.2) and 7 non-carriers (male=3, mean age=53.3) in the same family. In addition, we screened the same mutations in unrelated consecutive 500 hyperlipidemic patients (male=32, mean age=49.4) with mean LDL-C of 225.2±6.1mg/dl using PCR to determine its frequency and examined their clinical features. We identified an unrelated heterozygous ARH carrier and a non-carrier in the same family among unrelated to the original family. Serum LDL-C levels of heterozygous ARH carriers (mean=153.8±35.8mg/dl) were significantly higher than those of non-carriers (mean=108.2±41.4mg/dl, p<0.05). Serum triglyceride (151.9±110.7mg/dl vs 140.4±48.8mg/dl) and high-density lipoprotein cholesterol (57.4±11.0mg/dl vs 54.0±11.9mg/dl) levels were not different between them. Interestingly, heterozygous ARH carriers didn’t show any xanthomas including Achilles tendon (6.4±1.1mm vs 5.7±1.1mm) in contrast to FH, which is frequently associated with typical xanthoma. These results demonstrate that heterozygous ARH (Ins C599) carriers show higher LDL-C levels compared with non-carrier family member without tendon xanthomas observed in FH. We suggest that heterozygous ARH (Ins C599) carrier may explain a part of primary hypercholesterolemia.