Screening for familial hypercholesterolaemia

Unveiling Familial Hypercholesterolemia-Review, Cardiovascular Complications, Lipid-Lowering Treatment and Its Efficacy

Familial hypercholesterolemia (FH) is a genetic disorder primarily transmitted in an autosomal-dominant manner. We distinguish two main forms of FH, which differ in the severity of the disease, namely homozygous familial hypercholesterolemia (HoFH) and heterozygous familial hypercholesterolemia (HeFH). The characteristic feature of this disease is a high concentration of low-density lipoprotein cholesterol (LDL-C) in the blood. However, the level may significantly vary between the two mentioned types of FH, and it is decidedly higher in HoFH. A chronically elevated concentration of LDL-C in the plasma leads to the occurrence of certain abnormalities, such as xanthomas in the tendons and skin, as well as corneal arcus. Nevertheless, a significantly more severe phenomenon is leading to the premature onset of cardiovascular disease (CVD) and its clinical implications, such as cardiac events, stroke or vascular dementia, even at a relatively young age. Due to the danger posed by this medical condition, we have investigated how both non-pharmacological and selected pharmacological treatment impact the course of FH, thereby reducing or postponing the risk of clinical manifestations of CVD. The primary objective of this review is to provide a comprehensive summary of the current understanding of FH, the effectiveness of lipid-lowering therapy in FH and to explain the anatomopathological correlation between FH and premature CVD development, with its complications.

Lipid profile evaluation and severe hypercholesterolaemia screening in the middle-aged population according to nationwide primary prevention programme in Lithuania

BACKGROUND AND AIMS

Cardiovascular disease (CVD) is a major cause of premature death in Lithuania where abnormal lipid levels are very common among middle-aged adults. The aim of this study was to evaluate lipid profile in middle-aged Lithuanians and perform population-based severe hypercholesterolaemia (SH) screening.

METHODS

This study included men aged 40-54 and women aged 50-64 years without overt CVD, participating in the Lithuanian High Cardiovascular Risk (LitHiR) primary prevention programme during the period 2009-2016. Lipidograms of 92,373 adults (58.4% women and 41.6% men) included in the database were analysed and screening for SH was performed.

RESULTS

The mean levels of total cholesterol, LDL cholesterol (LDL-C) and triglycerides (TG) among participants were 6.08 mmol/l, 3.87 mmol/l, and 1.59 mmol/l, respectively. Any type of dyslipidaemia was present in 89.7%, and severe dyslipidaemia in 13.4% of the study population. 80.2% of adults without overt CVD had LDL-C ≥3 mmol/l. SH (LDL-C ≥6 mmol/l) was detected in 3.2% of study participants. Prevalence of SH decreased from 2.91% to 2.82% during the period 2009-2016 (p for trend = 0.003). LDL-C ≥6.5 mmol/l was observed in 1.5% of subjects while both LDL-C ≥6.5 mmol/l, and TG ≤ 1.7 mmol/l was found in 0.6% of subjects.

CONCLUSIONS

SH was present in 3.2% of the middle-aged population without overt CVD. Slightly decreasing prevalence of SH was observed during the period 2009-2016 in Lithuania. Likely phenotypic familial hypercholesterolaemia was observed in 1.5% of middle-aged Lithuanians. Further clinical and genetic evaluation of people with SH is needed to detect familial forms of SH.

The tertiary hospital laboratory; a novel avenue of opportunistic screening of familial hypercholesterolemia

Background

Familial hypercholesterolemia (FH) is a common monogenic hereditary lipid disorder characterised by increased serum low-density lipoprotein cholesterol (LDL-cholesterol) concentrations and high risk of premature atherosclerotic cardiovascular disease. The prevalence of FH identified in a tertiary hospital laboratory was investigated by performing an opportunistic screen for index cases.

Methods

The prevalence of likely FH based on LDL-cholesterol thresholds >4.9 mmol/L as employed by the Dutch Lipid Clinic Network Criteria (DLCNC) score was evaluated retrospectively in a single tertiary hospital laboratory over a six-month period (July to December 2016).

Results

4943 lipid profiles screened, 106 patients (mean age 53.2 ± 12.9 and 41% male) had LDL-cholesterol of >4.9 mmol/L after exclusion of 5 patients (0.1%) with secondary causes. Possible (n = 90) and probable/definite (n = 16) FH according to DLCNC score was seen in 1.8% and 0.4% of the overall screened population, respectively.

Conclusions

Point prevalence of screening for FH in patients undergoing lipid profile testing in a tertiary hospital laboratory was comparable with prevalence of FH in general population (based on 1 in 200-250). This supports the benefit of establishing an efficient "alert system" in conjunction with a trigger "reflex testing" to facilitate further formal FH scoring and exclusion of possible secondary causes of hyperlipidemia in potential index FH.

Improving the detection of familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is a dominantly inherited disorder of low-density lipoprotein (LDL) catabolism, which if untreated causes lifelong elevated LDL-cholesterol (LDL-c), accelerated atherosclerosis and premature cardiovascular disease. Recent evidence suggests the prevalence of heterozygous FH is ∼1:220, making FH the most common autosomal dominant condition. Lowering LDL-c with statin and lifestyle therapy reduces the risk of cardiovascular events. Furthermore, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors significantly lower LDL-c in addition to statin therapy, and early outcome data suggest improved vascular outcomes with these agents in FH patients in addition to statins. However, the vast majority of people with FH still remain undiagnosed. The onus is on clinicians to identify kindreds with FH, as PCSK9 inhibitors, although expensive, are funded for patients with FH in Australia. Multiple strategies for detecting FH have been proposed. The detection of index cases can be achieved through applying electronic screening tools to general practice databases, universal screening of children during immunisation, and targeted screening of patients with premature cardiovascular disease. Advances in genomic technology have decreased costs of genetic testing, improved the understanding of the pathogenesis of FH and facilitated cascade screening. However, awareness of FH amongst clinicians and the general public still requires optimisation. This review outlines recent advances in FH detection, including emerging strategies and challenges for the next decade.

Interpretative comments specifically suggesting specialist referral increase the detection of familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) is an under-diagnosed inherited condition characterised by elevated low density lipoprotein (LDL)-cholesterol and premature coronary artery disease. The requesting general practitioner of individuals with extremely elevated LDL-cholesterol measured by St John of God Pathology receives an interpretative comment on the lipid results highlighting possible FH. We sought to determine whether specifically recommending referral to the regional Lipid Disorders Clinic (LDC) increased referral and FH detection rates. A prospective case-control study of individuals with LDL-cholesterol ≥6.5 mmol/L was conducted. All individuals received an interpretative comment highlighting the possibility of FH. The cases comment also suggested LDC referral, and a subset of cases received the LDC's fax number (fax-cases) in addition. There were 231 individuals with an LDL-cholesterol ≥6.5 mmol/L; 96 (42%) controls and 135 (58%) cases, of which 99 were fax-cases. Twenty-four (18%) cases were referred to clinic compared with eight (8%) controls (p = 0.035). After specialist review and genetic testing, four probable and four definite FH individuals were detected amongst controls, compared with seven possible, eight probable and nine definite FH amongst cases. Genetic testing was performed in 31 (94%) individuals, 13 (42%) had a causative mutation identified. Interpretative commenting specifically recommending specialist review augments the detection of FH in the community.

The potential role of an expert computer system to augment the opportunistic detection of individuals with familial hypercholesterolaemia from a community laboratory

BACKGROUND

Familial hypercholesterolaemia (FH) is the most common monogenic cause of premature atherosclerotic cardiovascular disease (CVD). However, most individuals with FH remain undiagnosed. We sought to determine if an expert system (ES) at a community laboratory could identify information relevant for estimating an individual's likelihood of FH using the Dutch Lipid Clinic Network criteria (DLCNC).

METHODS

An ES (RippleDown®) retrospectively analysed laboratory results and clinical details on the current and previous lipid requests from a community laboratory in Western Australia, over 12months.

RESULTS

84,823 individuals had ≥1 LDL-cholesterol request with data available on 84,083 (99.1%). Clinical details were provided on 71,282 (84.8%) individuals' current or previous requests. History relevant to the DLCNC was present in 883 (1.1%) individuals, with premature CVD and non-cardiac vascular disease present in 177 and 64 individuals, respectively. Statin therapy was reported in 5118 individuals; 112 individuals with a current LDL-cholesterol of <6.5mmol/L had a previous LDL-cholesterol of ≥6.5mmol/L.

CONCLUSIONS

The ES was able to identify information that increased the likelihood of FH in 5471 cases. The ability to detect individuals with premature CVD and to classify them based on their highest LDL-cholesterol may augment FH detection, although further investigation is required to confirm this.

Clinically relevant lessons from Family HealthLink: a cancer and coronary heart disease familial risk assessment tool

PURPOSE

A descriptive retrospective study was performed using two separate user cohorts to determine the effectiveness of Family HealthLink as a clinical triage tool.

METHODS

Cohort 1 consisted of 2,502 users who accessed the public website. Cohort 2 consisted of 194 new patients in a Comprehensive Breast Center setting. For patient users, we assessed documentation of family history and genetics referral. For all users seen in a genetics clinic, the Family HealthLink assessment was compared with that performed by genetic counselors and genetic testing outcomes.

RESULTS

For general public users, the percentage meeting high-risk criteria were: for cancer only, 22.2%; for coronary heart disease only, 24.3%; and for both diseases, 10.4%. These risk stratification percentages were similar for the patient users. For the patient users, there often was documentation of family history of certain cancer types by oncology professionals, but age of onset and coronary heart disease family history were less complete. Of 142 with high-risk assignments seen in a genetics clinic, 130 (91.5%) of these assignments were corroborated. Forty-two underwent genetic testing and 17 (40.5%) had new molecular diagnoses established.

CONCLUSION

A significant percentage of individuals are at high familial risk and may require more intensive screening and referral. Interactive family history triage tools can aid this process.Genet Med 17 6, 493-500.

Familial hypercholesterolemia: A review

Familial hypercholesterolemia (FH) is a genetic disorder of lipoprotein metabolism resulting in elevated serum low-density lipoprotein (LDL) cholesterol levels leading to increased risk for premature cardiovascular diseases (CVDs). The diagnosis of this condition is based on clinical features, family history, and elevated LDL-cholesterol levels aided more recently by genetic testing. As the atherosclerotic burden is dependent on the degree and duration of exposure to raised LDL-cholesterol levels, early diagnosis and initiation of treatment is paramount. Statins are presently the mainstay in the management of these patients, although newer drugs, LDL apheresis, and other investigational therapies may play a role in certain subsets of FH, which are challenging to treat. Together these novel treatments have notably improved the prognosis of FH, especially that of the heterozygous patients. Despite these achievements, a majority of children fail to attain targeted lipid goals owing to persistent shortcomings in diagnosis, monitoring, and treatment. This review aims to highlight the screening, diagnosis, goals of therapy, and management options in patients with FH.

Lipoprotein apheresis and new therapies for severe familial hypercholesterolemia in adults and children

Familial hypercholesterolemia (FH), the most common and severe monogenic form of hypercholesterolemia, is an autosomal co-dominant disease characterized by an increased plasma low density lipoprotein (LDL)-cholesterol concentration and premature coronary heart disease (CHD). The clinical phenotype depends on the gene involved and severity of mutation (or mutations) present. Patients with homozygous or compound heterozygous FH have severe hypercholesterolemia (LDL-cholesterol >13 mmol/L) due to a gene dosing effect and without treatment have accelerated atherosclerotic CHD from birth, and frequently die of CHD before age 30. Cholesterol-lowering therapies have been shown to reduce both mortality and major adverse cardiovascular events in individuals with FH. Lipoprotein apheresis concomitant with lipid-lowering therapy is the treatment of choice for homozygous FH. This article describes the rationale and role of lipoprotein apheresis in the treatment of severe FH and outlines the recent advances in new pharmacotherapies for this condition.

Familial hypercholesterolemia in children and adolescents

PURPOSE OF REVIEW

This review provides an update and highlights the controversies regarding recent advances and recommendations regarding screening, diagnosis and treatment of children and adolescents with familial hypercholesterolemia.

RECENT FINDINGS

Both general cardiovascular risk and specific familial hypercholesterolemia guidelines for children and adolescents have recently been released. Universal lipid screening of children has been recommended, in addition to targeted screening. The role of genetic testing for targeted screening and diagnostic confirmation is less clear. Although lifestyle therapy remains of key importance, increasing evidence of safety and efficacy support the use of statin therapy. Early therapy has been associated with improvements in noninvasive measures of early atherosclerosis in children, which likely can be extrapolated to improved freedom from cardiovascular disease events over the lifespan, as has been observed in adults. The new guidelines provide general and specific recommendations as to how family history and additional risk factors and risk conditions should be incorporated in decisions regarding initiation of statin therapy at LDL-cholesterol cutpoints. Emerging evidence from observational studies are beginning to address concerns regarding the initiation at young ages and longer-term efficacy and safety.

SUMMARY

Children and adolescents with familial hypercholesterolemia can be identified and effective therapy with a statin initiated with consideration of the patients' overall cardiovascular risk profile, remaining mindful of the uncertainties regarding long-term safety.

Mipomersen and other therapies for the treatment of severe familial hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant condition with a population prevalence of one in 300–500 (heterozygous) that is characterized by high levels of low-density lipoprotein (LDL) cholesterol, tendon xanthomata, and premature atherosclerosis and coronary heart disease (CHD). FH is caused mainly by mutations in the LDLR gene. However, mutations in other genes including APOB and PCSK9, can give rise to a similar phenotype. Homozygous FH with an estimated prevalence of one in a million is associated with severe hypercholesterolemia with accelerated atherosclerotic CHD in childhood and without treatment, death usually occurs before the age of 30 years. Current approaches for the treatment of homozygous FH include statin-based lipid-lowering therapies and LDL apheresis. Mipomersen is a second-generation antisense oligonucleotide (ASO) targeted to human apolipoprotein B (apoB)-100. This review provides an overview of the pathophysiology and current treatment options for familial hypercholesterolemia and describes novel therapeutic strategies focusing on mipomersen, an antisense apoB synthesis inhibitor. Mipomersen is distributed mainly to the liver where it silences apoB mRNA, thereby reducing hepatic apoB-100 and giving rise to reductions in plasma total cholesterol, LDL-cholesterol, and apoB concentrations in a dose-and time-dependent manner. Mipomersen has been shown to decrease apoB, LDL-cholesterol and lipoprotein(a) in patients with heterozygous and homozygous FH on maximally tolerated lipid-lowering therapy. The short-term efficacy and safety of mipomersen has been established, however, injection site reactions are common and concern exists regarding the long-term potential for hepatic steatosis with this ASO. In summary, mipomersen given alone or in combination with standard lipid-lowering medications shows promise as an adjunct therapy in patients with homozygous or refractory heterozygous FH at high risk of atherosclerotic CHD, who are not at target or are intolerant of statins.

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.