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Background: Sitosterolemia is a rare autosomal recessive disorder caused by homozygous or compound heterozygous variants in ABCG5/ABCG8 . The disease is characterized by increased plasma plant sterols. Small case series suggest that patients with sitosterolemia have wide phenotypic heterogeneity with great variability on either plasma cholesterol levels or development of atherosclerotic cardiovascular disease. The present study aims to characterize the prevalence and clinical features of sitosterolemia participating in a familial hypercholesterolemia genetic cascade screening program., Methods: From 443 familial hypercholesterolemia index cases, 260 were negative for familial hypercholesterolemia genes and were sequenced for the ABCG5/8 genes. Clinical and laboratory characteristics of affected individuals were determined., Results: Eight (3.1%) index cases were found to be homozygous or compound heterozygous variant for ABCG5/ABCG8 genes, confirming the genetic diagnosis of sitosterolemia. Screening their relatives led to the identification of 6 additional confirmed sitosterolemia cases (3 homozygous and 3 compound heterozygous variant) and 18 carriers (heterozygous). The mean age of identified sitosterolemia cases (n=14) was 37.2±19.8 years, 50% were females, and 78.6% (all adults) presented either clinical or subclinical atherosclerotic cardiovascular disease. As expected, affected individuals presented elevated plasma plant sterol levels (mean β-Sitosterol and campesterol, respectively, 160.3±107.1 and 32.0±19.6 µg/mL) and the highest plasma LDL (low-density lipoprotein)-cholesterol was 269.0±120.0 mg/dL (range: 122-521 mg/dL). LDL-cholesterol mean reduction with therapy among cases was 65%. Eighty-three percent (83%) of identified sitosterolemia patients presented hematologic abnormalities., Conclusions: Testing genes associated with sitosterolemia in the molecular routine workflow of a familial hypercholesterolemia cascade screening program allowed the precise diagnosis of sitosterolemia in a substantial number of patients with varying LDL-C levels and high incidence of early atherosclerotic cardiovascular disease and hematologic abnormalities.

Background and Aims: Familial hypercholesterolemia (FH) is characterized by high LDL-cholesterol (LDL-C) and early atherosclerotic cardiovascular disease (ASCVD). With a lipid lowering therapy (LLT), most individuals with FH may have a longer ASCVD-free survival. However, there is scant data about older individuals with FH., Methods: We compared characteristics of genetically defined FH older individuals with age-matched non-FH counterparts., Results: From 4111 genotyped individuals, 462 older than 60 years were included (198 positive and 264 negative for FH variants). There were no differences regarding median age [%25; 75%] 66.0 (62.0; 71.0) and 66.0 (62.2; 71.0) years, p = 0.68 for FH and non-FH, respectively. In both groups, there was a higher frequency of females, however, there were more males in the FH group 37.4% vs. 24.2%, p = 0.002. No differences were seen between FH and non-FH in LLT use: 88.5% vs. 91.5%, p = 0.29. Despite a longer LLT duration in FH patients (with 11.0 (7.0; 20.0) vs. 7.0 (3.0; 13.0) years, p < 0.001), treatment was started late in both groups: at 54.0 (47.0; 61.0) and 59.0 (52.0; 64.0) years, p < 0.001, in FH and non-FH, respectively. FH had greater frequencies of previous and early ASCVD (40.9% vs. 27.3%, p = 0.002, and 22.2% vs. 9.0%, p < 0.001). In FH, male sex [HR (95%CI)] 2.67 (1.50-4.73), p = 0.001, and LLT onset age 0.96 (0.93-0.99), p = 0.009, were independently associated with ASCVD., Conclusions: Among hypercholesterolemic older individuals participating in a cascade screening program, the genetic diagnosis of FH was associated with higher ASCVD rates, emphasizing the relevance of a monogenic defect as the cause of long-lasting hypercholesterolemia and ASCVD risk, particularly in men., (Copyright © 2020 Elsevier B.V. All rights reserved.)