Diagnosis and screening for familial hypercholesterolaemia: finding the patients, finding the genes

Familial hypercholesterolaemia (FH) is a genetic disorder in which the concentration of serum cholesterol is elevated from birth and leads to premature coronary heart disease. FH is commonly caused by a mutation in the LDL receptor, but mutations in other genes can lead to a phenotype similar to FH. FH exhibits marked phenotypic variability due to genetic, metabolic and environmental factors. The presence of tendon xanthomata is the characteristic clinical sign seen in many patients with FH, but they may also have other non-specific signs of lipid disorders such as corneal arcus and xanthelasmata. Premature vascular disease is apparent in many patients. The wide variety of mutations and phenotypic variability have made it difficult to establish definite diagnostic criteria, but three sets of clinical criteria commonly used are the Simon Broome criteria, the Dutch Lipid Clinic criteria and the American criteria. FH screening fits the Wilson and Jungner recommendations for validity of a screening programme. Screening could be carried out on a population basis, in a clinical setting or by application to relatives of probands. This latter approach, termed cascade testing, appears to be the more cost-effective compared with population screening and can be carried out using clinical criteria or genetic testing, or by a combination of both methods. Clinicians need to be made more aware of the clinical features of FH and how to diagnose it in order to increase the index of suspicion and instigate appropriate treatment early, with the aim of preventing premature coronary heart disease.