Homozygous familial hypercholesterolemia in Japan

Familial hypercholesterolemia with special focus on Japan

Familial hypercholesterolemia (FH) is an inherited disorder characterized by increased low-density lipoprotein LDL) cholesterol and atherosclerotic cardiovascular disease. Although initial genetic analysis linked FH to LDL receptor mutations, subsequent work demonstrated that a gain-of-function mutation in the proprotein convertase subtilisin/kexin type 9 (PCSK9), which causes LDL-R degradation, was shown to be the cause of FH. In this review, we describe the history of research on FH, its clinical phenotyping and genotyping and advances in treatment with special focus on Japan.

Half a Century Tales of Familial Hypercholesterolemia (FH) in Japan

Familial hypercholesterolemia (FH) is a disease characterized by a triad: elevated low-density lipoprotein (LDL) cholesterol, tendon xanthomas, and premature coronary heart disease. Thus, it can be considered as a model disease for hypercholesterolemia and atherosclerotic cardiovascular disease (ASCVD). For the diagnosis of hetero-FH, the detection of Achilles tendon xanthomas by palpation or on X-ray is an indispensable diagnostic skill in clinical lipidology. To prevent the under-diagnosis and under-treatment of FH, the diagnostic criteria should be more convenient and user-friendly. For a patient with cutaneous or tendon xanthomas, the probability of FH is very high; however, an absence of xanthoma does not rule out FH.

Brown and Goldstein elucidated the pathogenesis of FH by their work on LDL-receptor (LDL-R), for which they were awarded the Nobel Prize in 1985. In the 1950s, FH patients were divided into heterozygous (hetero-) and homozygous (homo-) FH, and diagnosing homo- and hetero-FH based on the phenotypic features of ASCVD or xanthomas frequently became difficult without the DNA analysis of FH genes. It is estimated that heterozygous mutations in the LDL-R or the proprotein convertase subtilisin/kexin type 9 (PCSK9) gene will be found at a combined frequency of 0.005, which corresponds to 1/199 people in the general population in Japan.

Statins and anti-PCSK9 monoclonal antibodies are highly specific and efficient drugs for treating hetero- or homo-FH patients. Most clinical studies have reported an amelioration of ASCVD using long-term statin therapy. Clinical results using anti-PCSK9 monoclonal antibodies will emerge in a few years. In homo-FH patients, mipomersen and lomitapide are expected to yield good results. It is important to sequentially unravel the unrecognized pathogenetic mechanisms of FH to reduce its under-recognition and develop new management strategies for it.

Effect of Statin Therapy in 4-Year-Old Dichorionic Diamniotic Twins with Familial Hypercholesterolemia Showing Multiple Xanthomas

Familial hypercholesterolemia (FH) is characterized by a high level of low-density lipoprotein cholesterol (LDL-C) and is inherited as an autosomal dominant trait. We report 4-year-old dichorionic diamniotic twins (boy and girl) with FH who presented with multiple xanthomas on the face, both knees, both feet, and buttocks. Family history revealed vertical transmission of hypercholesterolemia from father to patients, thereby suggesting dominant inheritance. Lipid data of their mother did not match the criteria of FH. However, lipid data of maternal grandmother and maternal sister matched the criteria of FH. LDL receptor gene analysis of the family revealed that their father was heterozygous for a missense mutation, L547V, their mother was heterozygous for a nonsense mutation, C675X, and patients were compound heterozygous for L547V and C675X. After 10 months of treatment with pitavastatin (2 mg/day) and ezetimibe (10 mg/day), LDL-C decreased from 595 mg/dL to 267 mg/dL in the boy and from 530 mg/dL to 182 mg/dL in the girl. These findings suggest that lipid-lowering therapy with statin may be considered in pediatric patients with compound heterozygous FH (hetero FH) before inducing LDL apheresis, and gene analysis for true diagnosis in pediatric patients with multiple xanthomas should be considered, though they appear to be hetero FH from the family history and lipid data of parents.

Autosomal recessive hypercholesterolemia: a mild phenotype of familial hypercholesterolemia: insight from the kinetic study using stable isotope and animal studies

Autosomal recessive hypercholesterolemia (ARH) is an extremely rare inherited disorder, the cause of which is mutations in the low-density lipoprotein (LDL) receptor adaptor protein 1 (LDLRAP1) gene. Only 36 families with 14 different mutations have been reported in the literature to date. The clinical phenotype of ARH is milder than that of homozygous familial hypercholesterolemia (FH) caused by LDL receptor gene mutations. Recently, the lipoprotein metabolism of ARH was investigated in both humans and mice by several investigators, including ourselves. Based on these findings the preserved clearance of LDL receptor-dependent very-LDL (VLDL) may be a possible mechanism underlying the responsiveness to statins and the milder phenotype of ARH. Although ARH has been described as being "recessive," several studies, including ours, have indicated that a heterozygous carrier status of the LDLRAP1 gene is associated with mild hypercholesterolemia and exacerbates the phenotype of FH resulting from LDL receptor gene mutations. This review summarizes current understanding regarding ARH and its causative gene, LDLRAP1, and attempts to provide new insight into novel pharmacological targets for treating dyslipidemic patients.

Autosomal dominant hypercholesterolemia: needs for early diagnosis and cascade screening in the tunisian population

Autosomal dominant hypercholesterolemia (ADH) is characterized by an isolated elevation of plasmatic low-density lipoprotein (LDL), which predisposes to premature coronary artery disease (CAD) and early death. ADH is largely due to mutations in the low-density lipoprotein receptor gene (LDLR), the apolipoprotein B-100 gene (APOB), or the proprotein convertase subtilisin/kexin type 9 (PCSK9). Early diagnosis and initiation of treatment can modify the disease progression and its outcomes. Therefore, cascade screening protocol with a combination of plasmatic lipid measurements and DNA testing is used to identify relatives of index cases with a clinical diagnosis of ADH. In Tunisia, an attenuated phenotypic expression of ADH was previously reported, indicating that the establishment of a special screening protocol is necessary for this population.

An Infantile Case of Transient, Severe Hypercholesterolemia with Normalization after Complete Weaning from Breast-feeding

A 20-d-old boy was referred to our department because of hyperthyrotropinemia at neonatal mass screening and diagnosed with neonatal transient hyperthyrotropinemia. A follow-up examination when the patient was 5 mo old revealed severe hypercholesterolemia. Familial hypercholesterolemia was first suspected because of the patient’s significantly high levels of total and low-density lipoprotein cholesterol. The parent’s serum lipid profiles were examined and found to be normal. He was completely breast-fed until 6 mo of age. Breast milk was still the main source of food for a period following weaning. At 14 mo old, the patient was weaned completely from breast milk, and his serum cholesterol levels decreased dramatically. According to the normal lipid profiles of the patient’s parents and the spontaneous normalization of serum cholesterol levels after complete weaning from breast milk, breast-feeding was suggested to be responsible for his transient severe hypercholesterolemia. It is well documented that breast-fed infants have higher serum cholesterol levels than formula-fed infants. However, there is no reported case with severe hypercholesterolemia equivalent to or higher than the levels observed in the case of familial hypercholesterolemia. Although the exact mechanism is unknown, it is necessary to consider that a small number of cases develop severe hypercholesterolemia related to breast-feeding.

Fatal myocardial infarction at 4.5 years in a case of homozygous familial hypercholesterolaemia

Management of homozygous familial hypercholesterolaemia is notoriously difficult. For these patients, LDL apheresis is considered the treatment of choice. Treatment initiation is advocated generally from the age of seven years onwards (Thompson et al., Atherosclerosis 198:247-255, 2008). Here, we present the case of a young girl from a large inbred family of Turkish descent with homozygous familial hypercholesterolaemia and fatal outcome at the early age of 4½ years.In conclusion, this case suggests that management of homozygous familial hypercholesterolaemia may require earlier and more aggressive treatment, including LDL apheresis before the age of seven years.

Moderate phenotypic expression of familial hypercholesterolemia in Tunisia

BACKGROUND

Autosomal Dominant Hypercholesterolemia (ADH) is an autosomal dominant disease caused by mutations in the low density lipoprotein receptor (LDLR), apolipoprotein B (APOB), and proprotein convertase subtilisin/kexin type 9 (PCSK9) genes. Xanthomas and coronary heart diseases (CHD) at an early age are the major clinical manifestations of the disease.

METHODS

16 families with familial hypercholesterolemia from different regions in Tunisia participated in the study. Mutations within the LDLR gene were screened through DNA sequencing. Lipids values were measured by standard enzymatic methods.

RESULTS

We present here thirty five homozygotes and fifty six heterozygotes. Homozygotes presented extensive xanthomatosis, variable clinical manifestations of CHD, and total cholesterol levels in males and females of 17.26+/-4.18 and 17.64+/-2.59 mmol/L respectively. HDL-cholesterol levels were 0.62+/-0.24 and 1.00+/-0.61 mmol/L for males and females, respectively. None of the heterozygotes had tendon xanthomas (except for one female aged 62), eight had corneal arcus, and nine developed CHD mean between 46 and 88 years old. Total cholesterol levels in males and females ranged from 4.60 to 8.90 and from 4.30 to 10.50 mmol/L, respectively.

CONCLUSION

Tunisian FH heterozygotes are characterized by a moderate clinical and biological expression of the disease.

An 11-year-old boy with familial hypercholesterolemia showing multiple xanthomas and advanced atherosclerosis, who responded to lipid-lowering therapy using statin

Familial hypercholesterolemia (FH) is characterized by a high level of LDL-cholesterol (LDL-C) and a high prevalence of atherosclerotic coronary heart disease; however, hypercholesterolemia is usually the only clinical finding in children with heterozygous FH in their first decade of life. We report a case of FH in an 11-year-old boy who presented with multiple xanthomas at both elbows, thickened Achilles tendons, and hyperplasia of the intima-media complex of the carotid artery. Echocardiogram revealed partial calcification of the aortic and mitral valves, but no stenosis of the coronary arteries was detected on 3D-computed tomography. The activity of LDL receptors was reduced to 32% by lymphocyte assay. The family history showed vertical transmission of hypercholesterolemia from father to son, thereby suggesting dominant inheritance. After 12 months of treatment with statin and resin, his LDL-C decreased from 446 to 220 mg/dL, thickening of the Achilles tendons decreased from 1618 mm to 13 mm, and hyperplasia of the intima-media complex decreased from 1.3 mm to 0.7 mm. These findings suggest that our patient had heterozygous FH. However, based on his advanced atherosclerosis, we cannot exclude the possibility that our patient may be accompanying dyslipidemia due to causes in addition to heterozygous FH.

The challenge produced by familial homozygous hypercholesterolemia when treating premature coronary arterial disease in the young

BACKGROUND

Familial hypercholesterolemia is a monogenic, autosomal dominant disorder caused by mutations in the LDL receptor gene. Familial homozygous hypercholesterolemia results when both the alleles have the defective mutation. It is characterized by cutaneous and tendinous xanthomas, premature corneal arcing, and is associated with an increased risk of coronary arterial disease. It is also seriously underdiagnosed, resulting in delayed treatment.

METHODS

We present a cross-sectional study of 5 patients with familial homozygous hypercholesterolemia who presented to the department of cardiology at Sri Jayadeva Institute of Cardiology, Bangalore, India. All of them underwent coronary angiography as part of the investigation of their angina.

RESULTS

All 5 patients were in 2nd or 3rd decade of life, 4 being male, and 4 presenting with effort angina, the other having unstable angina. All had multiple tendinous xanthomas. The majority had significant high grade coronary arterial stenosis. Coronary arterial bypass grafting was necessary in 3, with the others undergoing percutaneous insertion of coronary arterial stents.

CONCLUSION

Familial homozygous hypercholesterolemia is a potentially dangerous risk factor that can result in premature coronary arterial disease in children and young adults. This can result in severe morbidity and premature death in young individuals. We also emphasise the need to screen first-degree relatives and extended family members, this playing an important role in early detection and treatment. Despite recent advances in treatment using lipid lowering agents, the disease remains a significant challenge.

[Familial hypercholesterolemia in Tunisia]

Familial hypercholesterolemia or autosomal dominant hypercholesterolemia is characterized by raised serum LDL (low density lipoproteins)-cholesterol levels, which result in excess deposition of cholesterol in tissues, leading to accelerated atherosclerosis and increased risk of premature coronary heart disease. Familial hypercholesterolemia results from defects in the hepatic uptake and degradation of LDL via the LDL receptor pathway. Familial hypercholesterolemia is commonly caused by a loss of function in the LDL receptor gene, or by a mutation in the gene encoding apolipoprotein B (APOB) or PCSK9 gene. In Tunisia, the frequency of this disease is about one of 165 for heterozygote. It is a higher frequency compared to most European countries, which is about one of 500 for heterozygote. Only five mutations in the LDLR gene were reported in this population. No mutations in the APOB or PCSK9 gene were reported.

Cutoff point separating affected and unaffected familial hypercholesterolemic patients validated by LDL-receptor gene mutants

Familial hypercholesterolemia (FH) results from low-density lipoprotein (LDL) receptor gene mutations. Heterozygotes have twice normal LDL-cholesterol concentrations in early childhood, and experience early myocardial infarction. We demonstrated bimodal cholesterol frequency distributions, independently confirming existence of an identifiable hypercholesterolemic subpopulation. We assayed blood lipids in 181 FH patients genetically diagnosed and 100 unaffected relatives. Receiver operating characteristics curves were constructed. Total cholesterol and LDL-cholesterol concentrations showed bimodality. A total cholesterol cutoff of 225 mg/dl produced results agreeing with DNA testing (specificity, 98.5%; sensitivity, 99.4%). An LDL-cholesterol cutoff of 161-163 mg/dl produced 98.5% specificity and 98.3% sensitivity. Areas under curves were 0.9826 +/- 0.0058 for total cholesterol, and 0.9852 +/- 0.0043 for LDL-cholesterol. In conclusion, we define total cholesterol and LDL-cholesterol levels of 225 and 160 mg/dl, respectively, as cutoff points of normal subjects and FH patients.

Dyslipidemia in young Japanese children: its relation to familial hypercholesterolemia and familial combined hyperlipidemia

BACKGROUND

Most cases of dyslipidemia found in adults are non-familial. However, in children, especially young children, dyslipidemias other than familial hypercholesterolemia (FH) have not yet been characterized.

METHODS

From April 1990 to March 1999, 56 181 children were screened, and 1380 showed abnormal levels of apolipoprotein B (more than 2.5 standard deviations above the mean). Among these, 1198 were re-examined and further characterized by measuring lipids and apolipoproteins, and by their familial histories.

RESULTS

Seventy-seven percent of the children (928 of 1198) recalled were diagnosed as being dyslipidemic. Ninety-one children were FH, 423 were type IIa, 128 were type IIb, 98 were type IV, and 188 were hypoalphalipoproteinemia. The presumed incidence of FH was 0.19%, IIa 0.87%, IIb 0.26%, IV 0.20%, and hypoalphalipoproteinemia 0.39%, taking into account the percentage of subjects who refused recall. At regular follow-ups, in many children with type IIb, the phenotypic expression changes from type IIb to IIa or IV. Thus, lipid and apolipoprotein levels were determined in 77 family members in 34 families of children with type IIb. Forty-five family members were dyslipidemic (type IIa 18, type IIb 11, type IV 16). As a result, 27 children (79%) with type IIb met the criteria for familial combined hyperlipidemia.

CONCLUSIONS

Children with dyslipidemia had more family or genetic background than adults. Unexpectedly, children with type IIb were mostly familial combined hyperlipidemia. Thus, setting appropriate eating patterns during childhood might be important for normalizing risk factors for atherosclerotic coronary heart disease, especially in children with FH or type IIb.

Coronary heart disease, hypercholesterolemia, and atherosclerosis. I. False premises

Lipid-rich caseous debris of advanced lesions stimulated interest in the role of cholesterol and lipids in atherosclerosis. Lipid-containing arterial lesions in cholesterol-overfed animals (cholesterolosis) and xanthomatous vascular lesions in subjects with familial hypercholesterolemia were then misrepresented as being atherosclerotic and led to the development of the hypercholesterolemic/lipid hypothesis. It is untenable that cholesterol, an essential multifunctional metabolite, is pathogenic at all blood levels and hypercholesterolemia is not prerequisite for human or experimental atherosclerosis. Serum cholesterol levels display a poor correlation with atherosclerosis at autopsy and with unreliable national coronary heart disease (CHD) mortality in each sex. Atherosclerosis topography and its iatrogenic production in humans and experimentally in herbivores by hemodynamic means both support a biomechanical causation and preclude causality by any circulating humoral factor. CHD, not a specific disease, is a nonspecific complication of many diseases including atherosclerosis and cannot be equated with coronary atherosclerosis due to differences in pathology and pathogenesis. Thus, extrapolations from CHD risk factors or correlations with fallacious vital statistics to atherosclerosis are invalid. It follows that the hypercholesterolemic/lipid hypothesis evolving from false premises, misuse of CHD, scientific misrepresentation, and fallacious data has no legitimate basis.

Coronary lesion morphology and prognosis in young males with myocardial infarction with or without familial hypercholesterolemia

The present study examined the angiographic characteristics and prognosis of young males under 40 years of age with acute myocardial infarction (AMI) and familial hypercholesterolemia (FH). The study group was divided into an FH group (n=16) and a non-FH group (n=27). Lesion morphology was classified as complex or smooth. Overall 36 patients were followed up for an average of 9.4 years. The frequency of angiographic normal or nonobstructive culprit lesions was significantly higher in the non-FH group (p<0.01). In contrast, the incidence of complex or totally occlusive lesions was higher in the FH group (p<0.01). At 10-year follow-up, survival rates from cardiac death (FH 85% vs non-FH 100%, p=0.06), from AMI (FH 43% vs non-FH 80%, p<0.05), and from any ischemic event at a new lesion (FH 9% vs non-FH 67%, p<0.01) were all reduced in the FH group. These results suggest that the mechanism of AMI in young male patients with FH differs from that in similar aged patients without FH, and that the overall prognosis of these patients is less favorable.

Clinical efficacy and safety of cerivastatin in the treatment of heterozygous familial hypercholesterolemia

Patients with heterozygous familial hypercholesterolemia are at especially high risk of premature coronary artery disease and usually require aggressive long-term lipid-lowering drug therapy to decrease plasma low-density lipoprotein (LDL) cholesterol concentrations to normal levels. In the present study, the lipid-lowering effects of cerivastatin in combination with cholestyramine and probucol were investigated in 20 patients with heterozygous familial hypercholesterolemia over a 20-week treatment period. After an initial 4-week treatment with once-daily 0.2 mg cerivastatin, serum total cholesterol and LDL cholesterol levels had decreased by a significant 22% and 25%, respectively (p <0.01). The addition of 8 g/day cholestyramine or 1 g/day probucol to ongoing cerivastatin therapy produced further significant reductions in total cholesterol of 16% and 16%, respectively, and in LDL cholesterol of 22% and 15%, respectively (p <0.01), over the 12-week combination therapy period. The potent lipid-lowering effects of combined treatment were accompanied by excellent toleration of study drugs. Only 2 patients experienced gastrointestinal side effects associated with cholestyramine therapy. There was no evidence of any abnormalities in creatine phosphokinase in either treatment group and only 2 patients exhibited minor increases in hepatic transaminases. This study has shown that cerivastatin can be safely combined with either cholesytramine or probucol to provide a safe and highly effective hypolipidemic treatment regimen for patients with heterozygous familial hypercholesterolemia.

The prevalence of peripheral vascular disease in familial hypercholesterolaemia

OBJECTIVES

In patients with familial hypercholesterolaemia (FH), the prevalence of haemodynamically significant peripheral vascular disease (PVD) was measured in relation to lipoproteins, general risk factors and the presence of coronary artery disease (CAD).

DESIGN

A case control study.

SETTING

The outpatient lipid clinic of a university hospital (tertiary referral centre).

SUBJECTS

Patients with heterozygous FH [n = 68; age 45.8 +/- 11.6 years; untreated LDL-cholesterol 9.2 +/- 2.0 mmol L-1] were compared with control subjects matched for gender, age, weight, smoking and presence of hypertension [n = 27; age 44.0 years; LDL-cholesterol 3.8 +/- 1.3 mmol L-1].

MAIN OUTCOME MEASURES

PVD was assessed during cholesterol-lowering treatment using ankle/arm blood pressure ratios and analyses of Doppler-derived blood flow velocities in the femoral artery at rest and during reactive hyperaemia. The diagnosis of CAD was assessed clinically.

RESULTS

Haemodynamically significant PVD was found in 21 (31%) FH patients and in one (3.7%) control subject, predominantly localized in the femoro-popliteal vessels. CAD was present in 30 (44.1%) FH patients and in one (3.7%) control subject. PVD could be demonstrated in 50% of FH patients with CAD [relative risk 3.2 (95% CI 1.4-7.2)] and in 19% as the first manifestation of vascular disease. Males and females were equally affected. Mean arterial blood pressure of FH patients with PVD was higher compared to FH patients without PVD.

CONCLUSIONS

Haemodynamically significant PVD appears to be more prevalent in FH patients than is generally assumed, especially in those with CAD. A relation with lipoprotein levels could not be demonstrated.

Coronary artery bypass grafting in familial hypercholesterolemia

Familial hypercholesterolemia is an autosomal dominant disorder caused by a mutation of the gene for the low-density lipoprotein receptor and is characterized by rapidly progressing coronary atherosclerosis. We assessed the long-term results of coronary artery bypass grafting performed during the past 13 years in 62 patients with heterozygous familial hypercholesterolemia, whose mean plasma total and low-density lipoprotein cholesterol level was 327 mg/dl, respectively. The patients had severe coronary atherosclerosis, with coronary stenosis index of 19.7, and the prevalence of extracoronary atherosclerotic lesions was 27%. Sixty-one patients underwent successful coronary artery bypass operation, with an average of 2.5 grafts, and the coronary stenosis index decreased to 7.1. After operation, all patients consumed a cholesterol-lowering diet and received drug therapy with pravastatin, probucol, or cholestyramine. Seven patients who were resistant to drug therapy were treated with plasma low-density lipoprotein apheresis. The cholesterol-lowering therapy reduced plasma total cholesterol level by 37%, low-density lipoprotein cholesterol level by 42%, and low-density lipoprotein/high-density lipoprotein cholesterol ratio by 37% (p < 0.001). During the follow-up period (mean, 52 months; range, 10 to 157 months), there was no cardiac death, but three patients died of malignant disease. The actuarial survival rate was 95% at 5 years and 89% at 12 years after operation. The actuarial freedom from recurrent angina was 90% at 5 years and 53% at 11 years after operation. Four patients underwent reoperation, an average of 8 years postoperatively, because of vein graft atherosclerosis. In spite of severe coronary atherosclerosis, these patients with familial hypercholesterolemia showed good long-term outcome after coronary artery bypass operation. The present findings suggest that aggressive use of arterial grafts, intensive cholesterol-lowering drug therapy, and low-density lipoprotein apheresis may be useful in patients with familial hypercholesterolemia.

Homozygous familial hypercholesterolemia among French Canadians in Québec Province

Nineteen patients with homozygous familial hypercholesterolemia (FH) living at the time of the 1981 Canada census are the subject of this report. Their mean age at that time was 15, with a range of 1 to 26 years. All patients had extensive xanthomatosis but showed variable clinical manifestations of coronary heart disease (CHD); five (mean age, 21; range, 11 to 27 years) died from sudden death due to CHD. Plasma cholesterol levels varied more than twofold (557 to 1532 mg/dl). Variation in the concentrations of both plasma and low density lipoprotein cholesterol, as well as apolipoprotein B, were related neither to age at death from CHD nor to the clinical course of CHD. The mean high density lipoprotein cholesterol concentration (37 mg/dl) was lower than the mean value (49 mg/dl) in the control population (p less than 0.001). Both the clinical and biochemical features of this cohort are typical of homozygous FH. The prevalence of homozygotes among French Canadians in Québec was approximately 1:275,000, and the minimum estimated frequency of heterozygotes was 1:270. In northeastern Québec, the frequency of homozygotes was approximately 1:100,000, and the minimum estimated frequency of heterozygotes was 1:154. Only Afrikaaners in South Africa have correspondingly higher frequencies.

Development of coronary heart disease in familial hypercholesterolemia

We studied the development of coronary artery disease in 10 homozygous and 692 heterozygous patients with familial hypercholesterolemia. Seventy-five (22%) male heterozygotes and 35 (10%) female heterozygotes were affected by myocardial infarction, which was first noted in men in the 3rd decade of life and in women in the 4th decade of life. Thirty-eight (70%) out of the deceased 54 heterozygous patients died of coronary heart disease. The mean age at death was significantly less in male heterozygotes (54 years) than in female heterozygotes (69 years). Five homozygous and 105 male and 56 female heterozygous patients received coronary angiographic evaluation. The regression equations between age (X) and coronary stenosis index (Y) obtained by assigning score (0 to 5) to each of 15 coronary artery segments were Y = 1.57X - 20.43 (r = 0.956, p less than 0.05) in the homozygotes, Y = 0.52X - 9.11 (r = 0.438, p less than 0.001) in the male heterozygotes, and Y = 0.47X - 12.54 (r = 0.343, p less than 0.01) in the female heterozygotes. From these data, we can assume that coronary artery stenosis detectable by angiography will occur after 17 and 25 years of age in male and female heterozygotes, respectively, and the treatment of heterozygotes with lipid-lowering drugs can be delayed until late adolescence.

New variant of low density lipoprotein receptor gene. FH-Tonami

A new variant of the low density lipoprotein receptor (LDLR) gene was ascertained through Southern blotting analysis of LDLR genes of 35 unrelated Japanese patients with heterozygous familial hypercholesterolemia (FH). This mutant gene had a 6 kilobase deletion which had eliminated only exon 15, an exon that encodes the O-linked sugar domain. The mutation was recognized in two patients with heterozygous FH. We refer to these patients as 'FH-Tonami', since they were both born in the Japanese district of Tonami. Although there is no evidence of a relation between families, the possibility of a common ancestor with FH does exist. Neonatal diagnosis of FH in two fetuses from one family was possible through analyses of their LDLR genes in cord blood samples at delivery.

Hypercholesterolemia and atherosclerosis: present and future therapy including LDL-apheresis

Atherosclerosis-induced coronary heart disease remains the major cause of death and disability in industrialized countries. Hypercholesterolemia is recognized as a causative factor in the development of atherosclerosis. While the lowering of cholesterol levels as a treatment goal has met with general agreement and acceptance, the preferred methods for doing so are still open to conjecture. This literature review discusses various factors in the hypercholesterolemia-atherosclerosis link and surveys a variety of treatment protocols including diet modification, drug therapy, surgical intervention, and plasmapheresis. Evidence is accumulating to prove that the ideal hypercholesterolemia therapy is one that reduces LDL levels while maintaining or increasing HDL levels. Because LDL-apheresis has this potential, this paper also reviews the various LDL-apheresis methods, including immunoadsorption, chemical affinity, and double-membrane filtration.

The longest-lived patient with homozygous familial hypercholesterolemia secondary to a defect in internalization of the LDL receptor

The authors report the longest-lived patient with homozygous familial hypercholesterolemia, the seventh case of a defect in internalization of low-density lipoprotein (LDL). The patient is a 57-year-old man, whose plasma total cholesterol (TC) and LDL-cholesterol (LDL-C) concentrations were 465-660 mg/100 ml and 461 mg/100 ml, respectively, while his plasma high-density lipoprotein-cholesterol (HDL-C) was 13.6-16.9 mg/100 ml. He was the product of a consanguineous marriage, and his parents, brothers, and a sister had mild hypercholesterolemia. His coronary angiogram revealed diffuse coronary artery narrowing. Receptor studies revealed that his fibroblasts bound as much LDL as normal cells, but could not internalize or degrade LDL.

Comparison of selectivity of LDL removal by double filtration and dextran-sulfate cellulose column plasmapheresis, and changes of subfractionated plasma lipoproteins after plasmapheresis in heterozygous familial hypercholesterolemia

The possibility of selective removal of low density lipoprotein (LDL) by double filtration (DF) and dextran-sulfate cellulose (DSC) column plasmapheresis in hypercholesterolemia and the acute recovery process of the subfractionated plasma lipoproteins after plasmapheresis in heterozygous familial hypercholesterolemia were investigated. Sixty-six percent of the LDL cholesterol and 42% of the HDL cholesterol were removed by 2.5 L DF plasmapheresis with the second filters having average pore diameters of 30 nm and 40 nm. Fifty-nine percent of the LDL cholesterol was removed by 2.5 L DSC column plasmapheresis, while HDL cholesterol did not change. Therefore, DSC column plasmapheresis could remove LDL much more specifically than DF plasmapheresis. VLDL increased rapidly and reached the preplasmapheresis level within four days after plasmapheresis. IDL returned to the preplasmapheresis level in 2 weeks. The LDL1 level was approximately 80% of the preplasmapheresis level on the 14th day. LDL2 reached the peak at the seventh day. HDL2 and HDL3 moved in the same manner and reached the peak on the seventh day after DF plasmapheresis.

Treatment of homozygous patients with familial hypercholesterolemia by double-filtration plasmapheresis

Two homozygous patients with familial hypercholesterolemia were treated by double-filtration plasmapheresis. The plasma separated by the first filter was subsequently led to the second filter of ethylene vinylalcohol co-polymer hollow fibers, which trap very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) preferentially to other plasma constituents. Serum, VLDL, IDL, LDL cholesterol levels decreased by 55, 68, 59 and 55%, respectively. HDL cholesterol levels decreased by 39%. Immunoglobulins and fibrinogen levels decreased significantly. Cutaneous and tendinous xanthomas became smaller. off

Causes of death in patients with familial hypercholesterolemia

Five out of 15 homozygotes and 41 out of 527 heterozygotes of familial hypercholesterolemia (FH) died during the past 10 years. Sudden death or heart failure was the cause of death in each of the 5 deceased homozygotes. Twenty heterozygotes died of myocardial infarction, 9 of sudden death, and 1 died after AC bypass surgery. Thus, 30 heterozygotes (73.2%) died of coronary heart disease (CHD). The mean age of death was significantly younger in male heterozygotes (54 years) than in the females (68 years). Rate of death from CHD in heterozygotes was 11 times higher than in the general population in Japan. Rate of death from pancreas cancer in FH was significantly higher than in the general population. These results suggest that FH is highly associated with pancreas cancer as well as CHD.

Coronary ectasia in a homozygous patient with familial hypercholesterolemia

A 23-year-old man with homozygous familial hypercholesterolemia was found to have coronary ectasia by coronary angiography. This case showed generalized xanthomatosis and severe hyper low density lipoproteinemia, and his cultured skin fibroblasts showed LDL receptor activities compatible with the receptor-defective homozygous type of familial hypercholesterolemia. Coronary angiography showed fusiform aneurysmal involvements in the right coronary artery and left circumflex artery, and 50% stenosis in the right coronary artery and left anterior descending artery. Thus, homozygous familial hypercholesterolemia produces coronary ectasia as well as premature coronary stenosis.

Homozygous familial hypercholesterolemic patients in China

Five homozygous patients with familial hypercholesterolemia (FH) are described. Their serum cholesterol levels were between 603 and 907 mg/dl, with an average of 714 mg/dl. The mean value of serum cholesterol levels of the obligate heterozygous parents was 270 mg/dl. In the patient group, 87% of the serum cholesterol was distributed in low density lipoprotein (LDL) and the mean LDL cholesterol level was about 8.4 times that in a control group. Phospholipids in HDL in the patient group were significantly lower than in the controls. Lipid assays of xanthoma tissues revealed that the major lipid was cholesterol and its esters. LDL receptor activity in fibroblasts from the homozygotes was markedly decreased. Two patients yielded less than 2% of normal receptor activity and were classified as receptor-negative. The other 3 revealed receptor activities greater than 2% but less than 25% of normal receptor activity and were classified as receptor-defective.

Cardiovascular features of homozygous familial hypercholesterolemia: analysis of 16 patients

Familial hypercholesterolemia (FH) is characterized by an autosomal codominant inheritance, an abnormality in low-density lipoprotein (LDL) receptor function, elevated plasma cholesterol levels and premature atherosclerosis. Sixteen patients with homozygous FH were studied to correlate the extent of their atherosclerotic disease with their lipid levels and receptor function. The age range at initial presentation was 3 to 38 years (mean 12), and at the last examination, 6 to 43 years (mean 20). The mean pretreatment total plasma cholesterol concentration for all patients was 729 +/- 58 mg/dl (+/- standard error of the mean), and the mean LDL cholesterol level was 672 +/- 58 mg/dl (normal 60 to 176). High-density lipoprotein cholesterol was 28 +/- 3 mg/dl (normal 30 to 74). In the 7 patients with FH who had symptoms of myocardial ischemia (Group I), the mean pretreatment LDL cholesterol value (817 +/- 62 mg/dl) was higher than that of the 9 asymptomatic patients (Group II) (560 +/- 74 mg/dl). In Group I, 5 of 7 patients had left or right coronary ostial narrowing and 3 had significant left ventricular outflow obstruction. Most coronary arterial narrowing occurred in the right coronary and left anterior descending arteries and the least amount in the left circumflex coronary artery. A femoral bruit was the physical finding that correlated best with the Group I population; brother:sister pairs revealed a milder clinical course for the female. Seven of the 16 patients have survived into their third decade without symptoms. Comparison of these persons with those in whom angina developed reveals a marked heterogeneity in their clinical course, which appears to be associated with receptor negative/defective status.

A case of heterozygous familial hypercholesterolemia associated with hyperthyroidism: effects of triiodothyronine on low-density lipoprotein receptor and cholesterol synthesis

A 58-year-old patient with heterozygous familial hypercholesterolemia (FH) showed normal levels of serum cholesterol (193 mg/dL) in coexistence with hyperthyroidism. After hyperthyroidism therapy with radioiodine and methimazole, the patient's lipid profile showed high concentrations of cholesterol (whole serum 318 mg/dL, VLDL 35 mg/dL, LDL 217 mg/dL, HDL 44 mg/dL). There was a significant inverse correlation between serum cholesterol levels and serum thyroxine levels (r = -0.815, p less than 0.01). Effects of triiodothyronine on LDL degradation and cholesterol synthesis from 14C-labeled acetate were studied in cultured skin fibroblasts. Triiodothyronine (T3) stimulated both LDL degradation and cholesterol synthesis in the cells from normal subjects and patients with heterozygous FH. The T3 increased cellular cholesterol synthesis markedly in the cells from patients with homozygous FH but did not increase LDL receptor activity. These results suggest that normal serum cholesterol levels in our case result in part from an enhancement of LDL receptors by thyroid hormone.

Reduction of serum cholesterol in heterozygous patients with familial hypercholesterolemia. Additive effects of compactin and cholestyramine

We studied the effects of the bile acid sequestrant cholestyramine, alone and in combination with the experimental agent compactin (ML-236B), a competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on serum levels of lipoproteins in 10 heterozygous patients with familial hypercholesterolemia. After cholestyramine treatment alone for 2 to 16 months, serum total and low-density lipoprotein cholesterol decreased by 20 and 28 per cent, respectively. With the addition of compactin for 12 weeks there was a 39 per cent total decrease in serum cholesterol from the control value--from 356 +/- 14 to 217 +/- 10 mg per deciliter (9.27 +/- 0.36 to 5.64 +/- 0.26 mmol per liter [mean +/- S.E.M.]; P less than 0.001)--and a 53 per cent decrease in low-density lipoprotein cholesterol--from 263 +/- 13 to 125 +/- 10 mg per deciliter (6.84 +/- 0.34 to 3.25 +/- 0.26 mmol per liter; P less than 0.001). High-density lipoprotein cholesterol, which had increased during cholestyramine treatment, remained at its higher level. No adverse effects were observed. If long-term safety can be demonstrated, the compactin-cholestyramine regimen may prove useful in heterozygous familial hypercholesterolemia. prove useful in heterozygous familial hypercholesterolemia.

Effects of ML-236b (compactin) on sterol synthesis and low density lipoprotein receptor activities in fibroblasts of patients with homozygous familial hypercholesterolemia

We studied biochemical genetics of low density lipoprotein (LDL) receptor mutations in fibroblasts from six homozygous and five heterozygous patients with familial hypercholesterolemia (FH). Three of six homozygotes are receptor-negative type and the other three homozygotes are receptor-defective type. In the cells from three receptor-negative homozygotes, the receptor binding, internalization, and degradation of (125)I-LDL were 0.5+/-0.3 ng/mg protein (mean+/-SEM), 14+/-8 and 8+/-6 ng/mg protein per 6 h (four normal cells; 44+/-3, 386+/-32, and 1,335+/-214 ng/mg protein per 6 h), respectively. In the cells from three receptor-defective homozygotes, the receptor binding, internalization, and degradation of (125)I-LDL were 6+/-2, 29+/-8, and 90+/-32 ng/mg protein per 6 h, respectively. In these six homozygotes, two pairs of siblings are included. Two siblings in the same family were classified as receptor-negative and two siblings in another family were classified as receptor-defective. The receptor-negative phenotypes and the receptor-defective phenotypes bred true in individual families. The cells from five heterozygotes showed approximately 46% of the normal activities of receptor.ML-236B, competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase), completely inhibited the incorporation of [(14)C]acetate into digitonin-precipitable sterols in fibroblasts from normal subjects and heterozygous and homozygous patients with FH with the concentration of 0.5 mug/ml. However, at 0.05 mug/ml of ML-236B sterol synthesis in fibroblasts from homozygotes was not completely suppressed in contrast to normal and heterozygous cells. Moreover, after preincubation with 0.05 mug/ml of ML-236B for 24 h in medium containing lipoproteins, sterol synthesis in the cells from receptor-negative homozygote showed 75% of the initial activity compared with that of 25% without preincubation. In the cells from a normal subject and a heterozygote, sterol synthesis was inhibited even after preincubation. These results suggest that (a) the inhibitory effect of ML-236B is overcome in homozygote cells by their high intracellular levels of HMG-CoA reductase and (b) that a higher dose of ML-236B may be required to lower serum cholesterol levels in FH homozygotes than in heterozygotes.

Cadiovascular complications of homozygous familial hypercholesterolaemia

Seven patients with homozygous familial hypercholesterolaemia, two female and five male, aged 12 to 25 years, underwent clinical and angiographic assessment to define the associated cardiovascular abnormalities. Four patients had angina, two of whom also had syncope on exertion. All had an ejection systolic murmur but no ejection click and a loud aortic second sound. All but one had a systolic gradient between the left ventricle and aorta, ranging from 20 to 80 mmHg at the time of presentation. Angiography showed a characteristic narrowing of the aortic root in all and five of the seven patients had coronary ostial stenosis. One patient died after an aortocoronary bypass and aortic valvotomy and two others underwent aortocoronary bypass and aortic valve replacement, one of whom also died after operation. The survivor and three other patients are now undergoing regular plasma exchange and remain well. The seventh patient died suddenly before the latter form of treatment could be started. These findings confirm that premature, severe atheroma of the aortic valve and root is a characteristic feature of homozygous familial hypercholesterolaemia and carries a high mortality.