Cascade screening and genetic variant pathogenicity assessment for familial hypercholesterolemia in a township‑based elderly population

Familial hypercholesterolemia (FH) is a common, autosomal semi-dominant inherited disorder causing premature cardiovascular disease. However, it remains underdiagnosed, especially in community settings. Early diagnosis, particularly in children, is critical for timely intervention. Furthermore, the pathogenicity of genetic variants of uncertain significance poses a major challenge for clinical interpretation. We conducted a systematic screening program in a town in Wujiang District, Suzhou, China. Eligible individuals (based on LDL-C ≥ 3.8 mmol/L, family history, or voluntary participation) underwent genetic testing for FH-related genes (LDLR, PCSK9, APOB and LDLRAP1) and pharmacogenetic variants (SLCO1B1 and APOE). Cascade screening was offered to relatives of probands with putative pathogenic variants. Identified variants were functionally characterized through in vitro assays, including intracellular expression, PCSK9 secretion, LDLR degradation and LDL uptake assays. Among 27 eligible participants, 13 (48.1%) carried putative pathogenic variants, with the majority (11/13) in LDLR. Cascade screening of eight families identified 13 additional carriers, with no pediatric carriers detected. Functional assays demonstrated that LDLR c.190delT and c.1448G > A resulted in complete loss of function, while c.1879G > A impaired protein maturation and reduced function to approximately 50% of wild-type. Other missense variants exhibited partial loss of function. For PCSK9, the c.658G > A variant was experimentally confirmed as a gain-of-function variant through in vitro studies. This study establishes a comprehensive FH diagnostic model from community screening to functional validation. Our findings confirm a high FH prevalence in this Chinese cohort and underscore the indispensable role of functional assays and pharmacogenetics in enabling precise diagnosis and personalized management.