Familial hypercholesterolaemia: a pressing issue for European health care

A systematic review of cost-effectiveness analysis of different screening strategies for familial hypercholesterolemia

AIMS

Diagnosis rate of familial hypercholesterolemia (FH) remained less than 10 % globally and the economic evaluation results of different FH screening strategies varied. This study aimed to systematically review the methodology and results of cost effectiveness analysis (CEA) of FH screening, which will provide evidence support for health-related decision-making.

METHODS

The Medline/PubMed, Embase, Cochrane Library, Web of science, National Health Service Economic Evaluation Database (NHSEED) and CEA Registry databases were electronically searched to collect full economic evaluation from the establishment of the databases to June 30, 2022. The quality of included studies was evaluated by the Consolidated Health Economic Evaluation Reporting Standards statement 2022 (CHEERS 2022) checklist.

RESULTS

Among 232 retrieved studies, 18 economic evaluations were included and all of them are from developed countries, with an average quality score of 0.73. The decision tree model and/or Markov model were constructed by thirteen articles (72 %). Twelve studies (67 %) adopted the healthcare perspective and the lifetime horizon to compare the costs and health outcome of different screening strategies. The results of eight studies indicated that cascade screening was a cost-effective strategy compared with no screening, which was more pronounced in younger adults. Universal screening in young adults aged 16 years or 18-40 years (n=3) and in children aged 1-2 years combined with reverse cascade screening (n=3) are both cost-effective. The probability of being cost-effective for cascade screening (n=6) and universal screening (n=1) of young aged 18-40 years were greater than 95 %.

CONCLUSIONS

Our review demonstrated the economic advantages of cascade screening, universal screening of young adults, and universal screening of newborns combined with reverse cascade screening. Further health economic evaluation is needed in children and in low- and middle-income countries.

[Prevention of cardiovascular diseases in childhood and adolescence]

Cardiovascular diseases are among the leading causes of death worldwide. Apart from a few exceptions heart attack, stroke and peripheral arterial occlusive disease first occur in later adulthood. The cornerstone for these diseases, however, is already laid by accelerated vascular aging in childhood. Apart from pediatric medical preventive check-ups, the medical care of the parents should also be a reason for taking action. A detailed family history enables many conclusions to be drawn about the cardiovascular risk of the next generation This requires targeted diagnostics and appropriate interventions in childhood ranging from lifestyle measures up to pharmaceutical therapy. In this context the current guidelines on the diagnostics and treatment of hypercholesterolemia and arterial hypertension in children and adolescents are also presented.

Parents' views of genetic testing and treatment of familial hypercholesterolemia in children: a qualitative study

Familial hypercholesterolemia (FH) is a serious inherited disorder, which greatly increases individuals’ risk of cardiovascular disease (CVD) in adult life. However, medical treatment and lifestyle adjustments can fully restore life expectancy. Whilst European guidance advises that where there is a known family mutation genetic testing is undertaken in early childhood, the majority of the at-risk population remain untested and undiagnosed. To date, only a small number of studies have explored parents’ and children’s experiences of testing and treatment for FH, and little is known about interactions between health professionals, parents, and children in clinic settings. In this study, in-depth interviews were undertaken with parents who had attended a genetics and/or lipid clinic for FH with their children (n = 17). A thematic analysis revealed four main themes: undertaking early prevention, postponing treatment, parental concerns, and the importance of the wider family context. The majority of parents supported genetic testing for FH in childhood. However, although some were very supportive of following early treatment recommendations, others expressed reluctance. Importantly, some parents were concerned that inappropriate information had been shared with their children and wished that more time had been given to discuss how, when, and what to tell in advance. Future research is needed to explore the long-term outcomes for children who undertake genetic testing and early treatment for FH and to trial interventions to improve the engagement, follow-up, and support of children who are at risk, or diagnosed, with this disorder.

Next generation sequencing applications for cardiovascular disease

The Human Genome Project (HGP), as the primary sequencing of the human genome, lasted more than one decade to be completed using the traditional Sanger's method. At present, next-generation sequencing (NGS) technology could provide the genome sequence data in hours. NGS has also decreased the expense of sequencing; therefore, nowadays it is possible to carry out both whole-genome (WGS) and whole-exome sequencing (WES) for the variations detection in patients with rare genetic diseases as well as complex disorders such as common cardiovascular diseases (CVDs). Finding new variants may contribute to establishing a risk profile for the pathology process of diseases. Here, recent applications of NGS in cardiovascular medicine are discussed; both Mendelian disorders of the cardiovascular system and complex genetic CVDs including inherited cardiomyopathy, channelopathies, stroke, coronary artery disease (CAD) and are considered. We also state some future use of NGS in clinical practice for increasing our information about the CVDs genetics and the limitations of this new technology. Key messages Traditional Sanger's method was the mainstay for Human Genome Project (HGP); Sanger sequencing has high fidelity but is slow and costly as compared to next generation methods. Within cardiovascular medicine, NGS has been shown to be successful in identifying novel causative mutations and in the diagnosis of Mendelian diseases which are caused by a single variant in a single gene. NGS has provided the opportunity to perform parallel analysis of a great number of genes in an unbiased approach (i.e. without knowing the underlying biological mechanism) which probably contribute to advance our knowledge regarding the pathology of complex diseases such as CVD.

Clinical characterization and mutation spectrum of German patients with familial hypercholesterolemia

BACKGROUND AND AIMS

Autosomal-dominant familial hypercholesterolemia (FH) is characterized by elevated plasma levels of low-density lipoprotein cholesterol (LDL-C) and a dramatically increased risk to develop cardiovascular disease (CVD). Mutations in three major genes have been associated with FH: the LDL receptor gene (LDLR), the apolipoprotein B gene (APOB), and the proprotein convertase subtilisin/kexin 9 gene (PCSK9). Here we investigated the frequency and the spectrum of FH causing mutations in Germany.

METHODS

We screened 206 hypercholesterolemic patients, of whom 192 were apparently unrelated, for mutations in the coding region of the genes LDLR, PCSK9 and the APOB [c.10580G > A (p.Arg3527Gln)]. We also categorized the patients according to the Dutch Lipid Clinic Network Criteria (DLCNC) in order to allow a comparison between the mutations identified and the clinical phenotypes observed. Including data from previous studies on German FH patients enabled us to analyse data from 479 individuals.

RESULTS

Ninety-eight FH causing variants were found in 92 patients (nine in related patients and 6 patients with two variants and likely two affected alleles), of which 90 were located in the LDLR gene and eight mutations were identified in the APOB gene (c.10580G > A). No mutation was found in the PCSK9 gene. While 48 of the LDLR mutations were previously described as disease causing, we found 9 new LDLR variants which were rated as "pathogenic" or "likely pathogenic" based on the predicted effect on the corresponding protein. The proportions of different types of LDLR mutations and their localization within the gene was similar in the group of patients screened for mutations here and in the combined analysis of 479 patients (current study/cases from the literature) and also to other studies on the LDLR mutation spectrum, with about half of the variants being of the missense type and clustering of mutations in exons 4, 5 and 9. The mutation detection rate in the 35 definite and 45 probable FH patients (according to DLCNC) was 77.1% and 68.9%, respectively. The data show a similar discriminatory power between the DLCNC score (AUC = 0.789 (95% CI 0.721-0,857)) and baseline LDL-C levels (AUC = 0.799 (95% CI = 0.732-0.866)).

CONCLUSIONS

This study further substantiates the mutation spectrum for FH in German patients and confirms the clinical and genetic heterogeneity of the disease.

Knowledge gaps in the management of familial hypercholesterolaemia. A UK based survey

BACKGROUND AND AIMS

Untreated individuals with familial hypercholesterolaemia (FH) are at increased risk of developing premature cardiovascular disease (CVD). Early diagnosis and treatment can result in a normal life expectancy. A recent survey commissioned by the European Atherosclerosis Society (EAS) reported a lack of awareness of FH in the general population. We conducted a survey to assess knowledge among healthcare professionals involved in the assessment and management of cardiovascular risk and disease in the United Kingdom.

METHODS

A survey designed to assess knowledge of diagnostic criteria, risk assessment, the role of cascade screening, and management options for patients with FH was distributed to 1000 healthcare professionals (response rate 44.3%). The same survey was redistributed following attendance at an educational session on FH.

RESULTS

151 respondents (40.5%) reported having patients under their care who would meet the diagnostic criteria for FH, but just 61.4% recognized that cardiovascular risk estimation tools cannot be applied in FH, and only 22.3% understood the relative risk of premature CVD compared to the general population. Similarly, just 65.9% were aware of recommendations regarding cascade screening.

CONCLUSIONS

The prevalence and associated risk of FH continue to be underestimated, and knowledge of diagnostic criteria and treatment options is suboptimal. These results support the recent Consensus Statement of the EAS and production of quality standards by the National Institute for Health and Care Excellence. Further work is required to formulate interventions to improve FH awareness and knowledge, and to determine the effect these interventions have on patient outcomes.

Improving detection of familial hypercholesterolaemia in primary care using electronic audit and nurse-led clinics

RATIONALE, AIMS AND OBJECTIVES

In the UK fewer than 15% of familial hypercholesterolemia (FH) cases are diagnosed, representing a major gap in coronary heart disease prevention. We wished to support primary care doctors within the Medway Clinical Commissioning Group (CCG) to implement NICE guidance (CG71) and consider the possibility of FH in adults who have raised total cholesterol concentrations, thereby improving the detection of people with FH.

METHODS

Utilizing clinical decision support software (Audit+) we developed an FH Audit Tool and implemented a systematic audit of electronic medical records within GP practices, first identifying all patients diagnosed with FH or possible FH and next electronically flagging patients with a recorded total cholesterol of >7.5 mmol L(-1) or LDL-C > 4.9 mmol L(-1) (in adults), for further assessment. After a 2-year period, a nurse-led clinic was introduced to screen more intensely for new FH index cases. We evaluated if these interventions increased the prevalence of FH closer to the expected prevalence from epidemiological studies.

RESULTS

The baseline prevalence of FH within Medway CCG was 0.13% (1 in 750 persons). After 2 years, the recorded prevalence of diagnosed FH increased by 0.09% to 0.22% (1 in 450 persons). The nurse advisor programme ran for 9 months (October 2013-July 2014) and during this time, the recorded prevalence of patients diagnosed with FH increased to 0.28% (1 in 357 persons) and the prevalence of patients 'at risk and unscreened' reduced from 0.58% to 0.14%.

CONCLUSIONS

Our study shows that two simple interventions increased the detection of FH. This systematic yet simple electronic case-finding programme with nurse-led review allowed the identification of new index cases, more than doubling the recorded prevalence of detected disease to 1 in 357 (0.28%). This study shows that primary care has an important role in identifying patients with this condition.

Carotid Plaques Correlates in Patients With Familial Hypercholesterolemia

Patients with familial hypercholesterolemia (FH) are at increased risk of premature cardiovascular disease. We compared factors associated with the presence of carotid plaques and carotid intima–media thickness (cIMT), markers of subclinical atherosclerosis, in 241 patients with FH (98, 40.7% men; mean age 41 ± 18.4 years). Patients with FH having carotid plaques (36.5%) had mean age, apolipoprotein (apo) B, glucose, apoA1, systolic blood pressure (SBP) and diastolic BP, waist/hip ratio (WHR), and body mass index higher than patients without plaques. Logistic regression revealed that apoB (odds ratio [OR] per 1 unit change 1.03, P = .005), high-density lipoprotein cholesterol (HDL-C; OR per 1 standard deviation [SD] change 0.59, P = .015), and non-HDL-C (OR per 1SD change 1.53, P = .04) were significantly associated with the presence of plaques. The cIMT correlated with obesity parameters, BP, apoB, glucose, high-sensitivity C-reactive protein, creatinine, γ-glutamyl transpeptidase, and alanine transaminase ( P < .001). Regression analysis revealed that cIMT was significantly associated with apoB, SBP, and WHR. These results confirm the role of apoB-containing lipoproteins and low HDL-C with the presence of carotid plaques and apoB, BP, and WHR with cIMT.

Isolevuglandin-type lipid aldehydes induce the inflammatory response of macrophages by modifying phosphatidylethanolamines and activating the receptor for advanced glycation endproducts

AIMS

Increased lipid peroxidation occurs in many conditions associated with inflammation. Because lipid peroxidation produces lipid aldehydes that can induce inflammatory responses through unknown mechanisms, elucidating these mechanisms may lead to development of better treatments for inflammatory diseases. We recently demonstrated that exposure of cultured cells to lipid aldehydes such as isolevuglandins (IsoLG) results in the modification of phosphatidylethanolamine (PE). We therefore sought to determine (i) whether PE modification by isolevuglandins (IsoLG-PE) occurred in vivo, (ii) whether IsoLG-PE stimulated the inflammatory responses of macrophages, and (iii) the identity of receptors mediating the inflammatory effects of IsoLG-PE.

RESULTS

IsoLG-PE levels were elevated in plasma of patients with familial hypercholesterolemia and in the livers of mice fed a high-fat diet to induce obesity and hepatosteatosis. IsoLG-PE potently stimulated nuclear factor kappa B (NFκB) activation and expression of inflammatory cytokines in macrophages. The effects of IsoLG-PE were blocked by the soluble form of the receptor for advanced glycation endproducts (sRAGE) and by RAGE antagonists. Furthermore, macrophages derived from the bone marrow of Ager null mice failed to express inflammatory cytokines in response to IsoLG-PE to the same extent as macrophages from wild-type mice.

INNOVATION

These studies are the first to identify IsoLG-PE as a mediator of macrophage activation and a specific receptor, RAGE, which mediates its biological effects.

CONCLUSION

PE modification by IsoLG forms RAGE ligands that activate macrophages, so that the increased IsoLG-PE generated by high circulating cholesterol levels or high-fat diet may play a role in the inflammation associated with these conditions.

Identification of the gene defect responsible for severe hypercholesterolaemia using whole-exome sequencing

Familial hypercholesterolaemia (FH) is a serious genetic metabolic disease. We identified a specific family in which the proband had typical homozygous phenotype of FH, but couldn’t detect any mutations in usual pathogenic genes using traditional sequencing. This study is the first attempt to use whole exome sequencing (WES) to identify the pathogenic genes in Chinese FH. The routine examinations were performed on all parentage members, and WES on 5 members. We used bioinformatics methods to splice and filter out the pathogenic gene. Finally, Sanger sequencing and cDNA sequencing were used to verify the candidate genes. Half of parentage members had got hypercholesterolaemia. WES identified LDLR IVS8[−10] as a candidate mutation from 222,267 variations. The Sanger sequencing showed proband had a homozygous mutation inherited from his parents, and this loci were cosegregated with FH phenotype. The cDNA sequencing revealed that this mutations caused abnormal shearing. This mutation was first identified in Chinese patients, and this homozygous mutation is a new genetic type of FH. This is the first time that WES was used in Chinese FH patients. We detected a novel genetic type of LDLR homozygous mutation. WES is powerful tools to identify specific FH families with potentially pathogenic gene mutations.

Systematic analysis of variants related to familial hypercholesterolemia in families with premature myocardial infarction

Familial hypercholesterolemia (FH) is an oligogenic disorder characterized by markedly elevated low-density lipoprotein cholesterol (LDLC) levels. Variants in four genes have been reported to cause the classical autosomal-dominant form of the disease. FH is largely under-diagnosed in European countries. As FH increases the risk for coronary artery disease (CAD) and myocardial infarction (MI), it might be specifically overlooked in the large number of such patients. Here, we systematically examined the frequency of potential FH-causing variants by exome sequencing in 255 German patients with premature MI and a positive family history for CAD. We further performed co-segregation analyses in an average of 5.5 family members per MI patient. In total, we identified 11 potential disease-causing variants that co-segregate within the families, that is, 5% of patients with premature MI and positive CAD family history had FH. Eight variants were previously reported as disease-causing and three are novel (LDLR.c.811G>A p.(V271I)), PCSK9.c.610G>A (p.(D204N)) and STAP1.c.139A>G (p.(T47A))). Co-segregation analyses identified multiple additional family members carrying one of these FH variants and the clinical phenotype of either FH (n=2) or FH and premature CAD (n=15). However, exome sequencing also revealed that some variants in FH genes, which have been reported to cause FH, do not co-segregate with FH. The data reveal that a large proportion of FH patients escape the diagnosis, even when they have premature MI. Hence, systematic molecular-genetic screening for FH in such patients may reveal a substantial number of cases and thereby allow a timely LDLC-lowering in both FH/MI patients as well as their variant-carrying family members.

Genetic testing of Korean familial hypercholesterolemia using whole-exome sequencing

Familial hypercholesterolemia (FH) is a genetic disorder with an increased risk of early-onset coronary artery disease. Although some clinically diagnosed FH cases are caused by mutations in LDLR, APOB, or PCSK9, mutation detection rates and profiles can vary across ethnic groups. In this study, we aimed to provide insight into the spectrum of FH-causing mutations in Koreans. Among 136 patients referred for FH, 69 who met Simon Broome criteria with definite family history were enrolled. By whole-exome sequencing (WES) analysis, we confirmed that the 3 known FH-related genes accounted for genetic causes in 23 patients (33.3%). A substantial portion of the mutations (19 of 23 patients, 82.6%) resulted from 17 mutations and 2 copy number deletions in LDLR gene. Two mutations each in the APOB and PCSK9 genes were verified. Of these anomalies, two frameshift deletions in LDLR and one mutation in PCSK9 were identified as novel causative mutations. In particular, one novel mutation and copy number deletion were validated by co-segregation in their relatives. This study confirmed the utility of genetic diagnosis of FH through WES.

Would raising the total cholesterol diagnostic cut-off from 7.5 mmol/L to 9.3 mmol/L improve detection rate of patients with monogenic familial hypercholesterolaemia?

A previous report suggested that 88% of individuals in the general population with total cholesterol (TC) > 9.3 mmol/L have familial hypercholesterolaemia (FH). We tested this hypothesis in a cohort of 4896 UK civil servants, mean (SD) age 44 (±6) years, using next generation sequencing to achieve a comprehensive genetic diagnosis. 25 (0.5%) participants (mean age 49.2 years) had baseline TC > 9.3 mmol/L, and overall we found an FH-causing mutation in the LDLR gene in seven (28%) subjects. The detection rate increased to 39% by excluding eight participants with triglyceride levels over 2.3 mmol/L, and reached 75% in those with TC > 10.4 mmol/L. By extrapolation, the detection rate would be ∼25% by including all participants with TC > 8.6 mmol/L (2.5 standard deviations from the mean). Based on the 1/500 FH frequency, 30% of all FH-cases in this cohort would be missed using the 9.3 mmol/L cut-off. Given that an overall detection rate of 25% is considered economically acceptable, these data suggest that a diagnostic TC cut-off of 8.6 mmol/L, rather than 9.3 mmol/L would be clinically useful for FH in the general population.

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28% of sequenced UK individuals with total cholesterol >9.3 mmol/L were found to have an FH mutation using NGS.

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Detection rate was higher (39%) in individuals with triglycerides lower than 2.3 mmol/L.

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By extrapolation, a 8.6 mmol/L (2.5 SD from the mean) cholesterol cut-off may be most economically sustainable.

The impact of genomics on public health practice

INTRODUCTION

Genomic science is developing rapidly, and engagement of public health professionals will be necessary to appraise new technologies and use them effectively.

SOURCES OF DATA

We use established domains of public health and draw on the literature and expert knowledge to illustrate how genomic technologies give rise to new applications.

AREAS OF AGREEMENT

Genomic technologies are useful in rare inherited disease, including population screening programmes, in health care and for surveillance, diagnosis and treatment of infectious disease.

AREAS OF CONTROVERSY

It is less clear when and how genetic susceptibility testing will be used for common chronic disease prevention or protection from environmental hazards.

GROWING POINTS

Developments in public health practice will be necessary to ensure rapid and effective implementation of genomic science.

AREAS TIMELY FOR DEVELOPING RESEARCH

Public health researchers should address how to accelerate the implementation of genomics for health benefit in developed and developing countries.

Advantages and versatility of fluorescence-based methodology to characterize the functionality of LDLR and class mutation assignment

Familial hypercholesterolemia (FH) is a common autosomal codominant disease with a frequency of 1:500 individuals in its heterozygous form. The genetic basis of FH is most commonly mutations within the LDLR gene. Assessing the pathogenicity of LDLR variants is particularly important to give a patient a definitive diagnosis of FH. Current studies of LDLR activity ex vivo are based on the analysis of 125I-labeled lipoproteins (reference method) or fluorescent-labelled LDL. The main purpose of this study was to compare the effectiveness of these two methods to assess LDLR functionality in order to validate a functional assay to analyse LDLR mutations. LDLR activity of different variants has been studied by flow cytometry using FITC-labelled LDL and compared with studies performed previously with 125I-labeled lipoproteins. Flow cytometry results are in full agreement with the data obtained by the 125I methodology. Additionally confocal microscopy allowed the assignment of different class mutation to the variants assayed. Use of fluorescence yielded similar results than 125I-labeled lipoproteins concerning LDLR activity determination, and also allows class mutation classification. The use of FITC-labelled LDL is easier in handling and disposal, cheaper than radioactivity and can be routinely performed by any group doing LDLR functional validations.

Whole-exome sequencing in an extended family with myocardial infarction unmasks familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia (FH) is an autosomal-dominant disease leading to markedly elevated low-density lipoprotein (LDL) cholesterol levels and increased risk for premature myocardial infarction (MI). Mutation carriers display variable LDL cholesterol levels, which may obscure the diagnosis. We examined by whole-exome sequencing a family in which multiple myocardial infarctions occurred at a young age with unclear etiology.

METHODS

Whole-exome sequencing of three affected family members, validation of the identified variant with Sanger-sequencing, and subsequent co-segregation analysis in the family.

RESULTS

The index patient (LDL cholesterol 188 mg/dL) was referred for molecular-genetic investigations. He had coronary artery bypass graft (CABG) at the age of 59 years; 12 out of 15 1st, 2nd and 3rd degree relatives were affected with coronary artery disease (CAD) and/or premature myocardial infarction (MI). We sequenced the whole-exome of the patient and two cousins with premature MI. After filtering, we were left with a potentially disease causing variant in the LDL receptor (LDLR) gene, which we validated by Sanger-sequencing (nucleotide substitution in the acceptor splice-site of exon 10, c.1359-1G > A). Sequencing of all family members available for genetic analysis revealed co-segregation of the variant with CAD (LOD 3.0) and increased LDLC (>190 mg/dL), following correction for statin treatment (LOD 4.3). Interestingly, mutation carriers presented with highly variable corrected (183-354 mg/dL) and on-treatment LDL levels (116-274 mg/dL) such that the diagnosis of FH in this family was made only after the molecular-genetic analysis.

CONCLUSION

Even in families with unusual clustering of CAD FH remains to be underdiagnosed, which underscores the need for implementation of systematic screening programs. Whole-exome sequencing may facilitate identification of disease-causing variants in families with unclear etiology of MI and enable preventive treatment of mutation carriers in a more timely fashion.

Familial hypercholesterolemia: developments in diagnosis and treatment

BACKGROUND

Familial hypercholesterolemia (FH) is a congenital disorder of lipid metabolism characterized by a marked elevation of the plasma concentration of LDL (low-density lipoprotein) cholesterol beginning in childhood and by the early onset of coronary heart disease. It is among the commonest genetic disorders, with an estimated prevalence in Germany of at least 1 per 500 persons.

METHOD

Review of pertinent literature retrieved by a selective search.

RESULTS

FH is underdiagnosed and undertreated in Germany. It is clinically diagnosed on the basis of an elevated LDL cholesterol concentration (>190 mg/dL [4.9 mmol/L]), a family history of hypercholesterolemia, and early coronary heart disease, or the demonstration of xanthomas. The gold standard of diagnosis is the identification of the underlying genetic defect, which is possible in 80% of cases and enables the identification of affected relatives of the index patient. The recommended goals of treatment, based on the results of observational studies, are to lower the LDL cholesterol concentration by at least 50% or to less than 100 mg/dL (2.6 mmol/L) (for children: <135 mg/dL [3.5 mmol/L]). The target value is lower for patients with clinically overt atherosclerosis (<70 mg/dL [1.8 mmol/L]). Statins, combined with a health-promoting lifestyle, are the treatment of choice. Lipoprotein apheresis is used in very severe cases; its therapeutic effects on clinical endpoints and its side effect profile have not yet been documented in randomized controlled trials.

CONCLUSION

Familial hypercholesterolemia is a common disease that can be diagnosed simply and reliably on clinical grounds and by molecular genetic testing. Timely diagnosis and appropriate treatment can lower the risk of atherosclerosis in heterozygous patients to that of the general population.