Familial hypercholesterolaemia (FH) is caused by pathogenic variants in LDLR, APOB or PCSK9. Impaired low-density lipoprotein (LDL) receptor function leads to decreased LDL catabolism and premature atherosclerotic cardiovascular disease (ASCVD). Thousands of LDLR variants are known, but assignation of pathogenicity requires accurate phenotyping, family studies and assessment of LDL receptor function. Precise, genetic diagnosis of FH using targeted next generation sequencing allows for optimal treatment, distinguishing FH from pathogenically distinct disorders requiring different treatment. Polygenic hypercholesterolaemia resulting from an accumulation of LDL cholesterol-raising single nucleotide polymorphisms (SNPs) could also be suspected by this approach. Similarly, ASCVD risk could be estimated by broader sequencing of cholesterol and non-cholesterol-related genes. Both of these areas require further research. The clinical management of FH, focusing on the primary or secondary prevention of ASCVD, has been boosted by PCSK9 inhibitor therapy. The efficacy of PCSK9 inhibitors in homozygous FH may be partly predicted by the LDLR variants. While expanded genetic testing in FH is clinically useful in providing an accurate diagnosis and enabling cost-effective testing of relatives, further research is needed to establish its value in improving clinical outcomes.