Familial hypercholesterolaemia: A model of care for Australasia

Familial hypercholesterolaemia in children and adolescents: a new paediatric model of care

Familial hypercholesterolaemia (FH) is a common genetic disorder affecting more than 8000 children and adolescents throughout Australia. It results in marked elevation in plasma low-density lipoprotein cholesterol levels from birth that predisposes individuals to premature coronary heart disease in adult life. The majority of children and adolescents with FH are undiagnosed, as symptoms and signs only develop after decades of hypercholesterolaemia. Cascade screening of family members after detecting FH in an index case is an effective approach that allows the diagnosis of FH to be made in the young, before significant atherosclerosis develops. With the availability of effective therapies, mainly statins, paediatricians are ideally placed to improve the outcomes of this disorder by detecting and managing hypercholesterolaemia in childhood, thereby preventing premature coronary artery disease. We describe a new paediatric model of care for FH.

Familial hypercholesterolemia in the danish general population: prevalence, coronary artery disease, and cholesterol-lowering medication

CONTEXT

The diagnosis of familial hypercholesterolemia (FH) can be made using the Dutch Lipid Clinic Network criteria. This employs the personal and family history of premature coronary artery disease and hypercholesterolemia and the presence of a pathogenic mutation in the low-density lipoprotein receptor (LDLR) and apolipoprotein B (APOB) genes.

OBJECTIVE

We employed this tool to investigate the prevalence of FH and the associations between FH and coronary artery disease and cholesterol-lowering medication in the Copenhagen General Population Study.

SETTING

The study was of an unselected, community-based population comprising 69,016 participants.

MAIN OUTCOME MEASURES

FH (definite/probable) was defined as a Dutch Lipid Clinic Network score higher than 5. Coronary artery disease was myocardial infarction or angina pectoris.

RESULTS

The prevalence of FH was 0.73% (one in 137). Of participants with FH, 20% had an LDLR or APOB mutation. The prevalence of coronary artery disease among FH participants was 33%. Only 48% of subjects with FH admitted to taking cholesterol-lowering medication. The odds ratio for coronary artery disease off cholesterol-lowering medication was 13.2 (10.0-17.4) in definite/probable FH compared with non-FH subjects, after adjusting for age, gender, body mass index, hypertension, metabolic syndrome and diabetes, and smoking. The corresponding adjusted odds ratio for coronary artery disease in FH subjects on cholesterol-lowering medication was 10.3 (7.8-13.8).

CONCLUSION

The prevalence of FH appears to be higher than commonly perceived in a general population of white Danish individuals, with at least half of affected subjects not receiving cholesterol-lowering medication. The very high risk of coronary artery disease irrespective of use of medication reflects the extent of underdiagnosis and undertreatment of FH in the community and primary care.

Multicenter study to determine the diagnosis criteria of heterozygous familial hypercholesterolemia in Japan

AIM

Heterozygous patients of familial hypercholesterolemia (FH) are known to have a high risk of coronary artery disease (CAD). Early diagnosis and prompt treatment are necessary to prevent their CAD. In this study we tried to amend the Japanese diagnostic criteria of FH for general practitioners by examining each component of the current criteria.

METHODS

A multicenter study was performed, which included 1356 dyslipidemic patients at 6 centers. Pretreatment demographic information including LDL-cholesterol (LDL-C), Achilles tendon thickness (ATT), family history of FH and premature CAD and the result of genetic analysis were analyzed.

RESULTS

Of 1356 patients, 419 were diagnosed with FH by criteria in 1988, which were used as a golden standard. We tried to define FH according to 3 conventional major items, i.e., 1) LDL-C, 2) ATT and/or cutaneous nodular xanthomas (CX), 3) family history of FH and/or family history of premature CAD. We then determined the cutoff of LDL-C using the new criteria. When we used 180 mg/dL as the cutoff of LDL-C, 94.3% of FH patients and 0.85% of non-FH satisfied 2 or more criteria. When we used 190 mg/dL, 92.1% of FH and 0.85% of non-FH satisfied 2 or more criteria; therefore, we chose 180 mg/dL for the cutoff of LDL-C in the new criteria and proposed that the diagnosis of definite FH can be made if 2 or more criteria are satisfied.

CONCLUSIONS

We examined each component for the diagnosis of heterozygous FH in a multicenter study in Japan.

Opportunistic screening for familial hypercholesterolaemia via a community laboratory

Background

Familial hypercholesterolaemia (FH) is an inherited disorder characterized by increased serum low-density lipoprotein (LDL)-cholesterol concentrations and premature atherosclerotic cardiovascular disease. The majority of people with FH are currently undiagnosed. We sought to determine the ability of a community laboratory to screen for individuals with potential FH.

Methods

Serum LDL-cholesterol concentrations issued by a private community laboratory in Western Australia were reviewed over a one-year period (1 May 2010 to 31 April 2011). We assessed the prevalence of possible FH based on LDL-cholesterol thresholds employed by the Make Early Diagnosis-Prevent Early Death (MED-PED), the Simon Broome Registry and the Dutch Lipid Clinic Network criteria.

Results

During this period, 84,823 people had 99,467 serum LDL-cholesterol measurements, with 91.8% requested by general practitioners. A secondary cause of hypercholesterolaemia was identified in 8.3% of subjects with an LDL-cholesterol ≥5.0 mmol/L. The prevalence of FH based on an LDL-cholesterol ≥6.5 mmol/L, the 99.75th percentile, was 1:398 in this sample population; similarly, the MED-PED LDL-cholesterol criteria gave a prevalence of 1:482.

Conclusions

The community laboratory is well placed to screen opportunistically for subjects with potential FH. This may be achieved using either the MED-PED criteria or a serum LDL-cholesterol cut-off point of ≥6.5 mmol/L, irrespective of age. Further investigation is required to determine the most effective method of identifying these individuals and, thereby, ensuring referral to a specialist lipid clinic.

Identification of people with heterozygous familial hypercholesterolemia

PURPOSE OF REVIEW

Familial hypercholesterolemia is an underdiagnosed autosomal codominant genetic condition associated with significantly increased risk of early cardiovascular disease when untreated. Early diagnosis and treatment decrease the excess risk, and strategies for identification of affected individuals are being developed worldwide. This review will discuss, from a clinician's perspective, some of the issues involved in identifying people with familial hypercholesterolemia.

RECENT FINDINGS

Several sets of recommendations have been published outlining the strategies for identification of people with familial hypercholesterolemia in various countries and regions. These include Australasia, Europe, and the USA.

SUMMARY

Continuing efforts to find the best methods for identification of people with familial hypercholesterolemia are needed to ensure that this very treatable inherited condition is diagnosed early enough to prevent the development of atherosclerotic vascular disease.

Screening for familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is an autosomal dominant disorder characterised by increased plasma concentrations of low density lipoprotein (LDL) cholesterol leading to atherosclerosis and premature coronary heart disease (CHD) and death. The clinical diagnosis of FH is based on a personal and family history, physical examination findings and LDL-cholesterol concentrations. FH is primarily caused by mutations in the LDL-receptor gene (LDLR), and less frequently by mutations in genes for APOB and the more recently identified PCSK9. Lifestyle modification and pharmacotherapy can delay or prevent the onset of CHD in FH. It is estimated that only 20% of cases have been diagnosed in Australia and that the majority are inadequately treated. Screening options for FH include population screening (of children or adults), targeted screening of patients with premature CHD and their relatives, or opportunistic screening such as flagging laboratory lipid reports. Cascade screening, a form of targeted screening, is an ethically acceptable, cost-effective strategy for the identification of FH. However, for screening to be successful, medical practitioners need to be aware of the signs and diagnosis of FH and the benefits of early treatment.