Functional Analysis of 3'UTR Variants at the LDLR and PCSK9 Genes in Patients with Familial Hypercholesterolemia

Area of Science:

• Genetics
• Molecular Biology
• Cardiovascular Disease

Background:

• Familial hypercholesterolemia (FH) is an inherited condition affecting 1 in 200-250 individuals, increasing risk for early coronary artery disease.
• Current genetic testing often misses variants in 3' untranslated regions (3'UTRs) of key genes like LDLR and PCSK9.
• These 3'UTR variants may influence microRNA binding and gene expression, potentially contributing to FH.

Purpose of the Study:

• To comprehensively analyze the 3'UTR regions of LDLR and PCSK9 in patients with suspected FH.
• To identify novel genetic variants within these regions and assess their potential pathogenicity.
• To investigate the functional impact of identified variants on gene expression.

Main Methods:

• Next-generation sequencing was employed to analyze the 3'UTR regions of LDLR and PCSK9 in 409 patients.
• In silico pathogenicity prediction was performed for identified variants.
• Luciferase reporter assays were used for functional validation of selected variants.

Main Results:

• Twenty-one low-frequency variants (<1% allelic frequency) were identified in the 3'UTRs of LDLR (14 variants) and PCSK9 (8 variants).
• LDLR:c.*653G > C variant demonstrated a 41% decrease in luciferase expression.
• PCSK9:c.*950C > T variant showed a 41% increase in PCSK9 expression, suggesting a functional impact.

Conclusions:

• Genetic analysis of LDLR and PCSK9 3'UTR regions can enhance the diagnostic accuracy of FH.
• Identified variants, such as LDLR:c.*653G > C and PCSK9:c.*950C > T, may contribute to the hypercholesterolemia phenotype.
• These findings highlight the importance of exploring non-coding regions in genetic diagnostics for complex diseases.