Autor(es): Ferreira, Maria Simões ; Ramos, Diana ; Rato, Inês ; Jannes, Cinthia E. ; Larrea-Sebal, Asier ; Martín, César ; Bourbon, Mafalda ; Alves, Ana Catarina
Data: 2025
Identificador Persistente: http://hdl.handle.net/10400.18/10526
Origem: Repositório Científico do Instituto Nacional de Saúde
Assunto(s): APOB; Functional Studies; Familial Hypercholesterolemia; LDL Cholesterol; Doenças Cardio e Cérebro-vasculares
Familial hypercholesterolemia (FH) is a condition characterized by increased LDL cholesterol levels with APOB variants accounting for about 5-10% of FH cases. However, variants in this gene may be more common than initially estimated since the entire APOB gene has only recently started to be sequenced. Although most of the alterations are missense, nonsense variants and small indels in exon 29 were also identified in individuals with FH phenotype and can be the cause of disease. This work aimed to characterize APOB variants identified in individuals with clinical diagnosis of FH. Moreover, we intended to do an overview of the APOB variants presenting functional studies. PubMed repository was consulted to collect publications regarding functional characterization of APOB variants. For variant characterization, LDL was isolated through sequential ultracentrifugation. ED-LDLR fragments purified from HEK293 cells were incubated with the different APOB variants and antibodies, to determine apoB affinity for LDLR by ELISA assay. CHO-ldlA7 cells were transfected with wt LDLR plasmid and incubated with FITC-labeled LDL to determine LDL binding and uptake by flow cytometry. In the literature there are 23 APOB variants with functional studies, six of which characterized by our group. Fourteen variants affecting apoB normal function; the remaining results presenting normal apoB function. Recently we characterized 8 more variants: p.(Ala1393Val), p.(Asp1456Asn), p.(Met2042Thr), p.(Asp2213del), p.(Ile3374Thr), p.(Val4295Leu) and p.(Arg4519Thr) that do not appear to impact apoB's binding to the LDLR; p.(Gln4316*) demonstrated reduced affinity for the LDL receptor. Functional studies play a critical role in assessing the pathogenicity of genetic variants and are among the key criteria for variant classification. These in-depth analyses confirm clinical diagnosis and provide essential insights for developing personalized treatment strategies. In the future, we aim to increase the number of studied variants, starting with 15 more variants from the Portuguese FH Study.
