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Abstract(s)
Familial hypercholesterolaemia (FH) is an autosomal semi dominant disorder of lipid metabolism
clinically characterized by increased levels of circulating LDL cholesterol and associated with elevated
cardiovascular risk. The genetic diagnosis is usually based on the analysis of LDLR, APOB, and PCSK9
genes. APOB variants are responsible for 5-10% of FH cases, and the variant spectrum of APOB has
increased due to sequencing of the whole gene through Next Generation Sequencing, consequently
increasing the number of variants that need to be functionally assessed.
This dissertation aimed to verify the correlation between phenotype and genotype in individuals
from the Portuguese FH Study, as well as create a database including all APOB variants found up to
date in this study. Moreover, it was intended to characterize two APOB variants identified in subjects
from this cohort.
Graphics regarding LDL cholesterol levels were designed for index cases FH positive and
negative and relatives FH positive. The variants previously detected by NGS were confirmed by PCR
and Sanger sequencing, and cascade screening was carried out in families. All APOB variants with MAF
<1% were gathered into a database. LDL from index cases and relatives was separated using sequential
ultracentrifugation and labelled with FITC for uptake assessment by flow cytometry in CHO-ldlA7 cells,
and proliferation assays were performed with U937 cells.
A definite diagnosis was possible for 4 individuals carrying known pathogenic variants, and
c.6639_6641del/p.(Asp2213del) and c.10121T>C/p.(Ile3374Thr) alterations from exon 26 were
functionally assessed. In vitro studies showed a neutral effect on the apoB function for these variants.
Furthermore, 143 different variants were discovered located throughout the whole gene, of which more
than 90% were variants of uncertain significance.
Functional studies, combined with the association between phenotype and genotype, allow a
better and more personalized treatment according to the needs of each individual.
Description
Tese de mestrado, Biologia Humana e Ambiente, 2023, Universidade de Lisboa, Faculdade de ciências
Keywords
hipercolesterolemia familiar APOB diagnóstico molecular base de dados estudos funcionais Teses de mestrado - 2023