Hokuriku-plus familial hypercholesterolaemia registry study: rationale and study design.

INTRODUCTION: Familial hypercholesterolaemia (FH) is an autosomal-dominant inherited genetic disease. It carries an extremely high cardiovascular risk associated with significantly elevated low-density lipoprotein (LDL) cholesterol. The diagnostic rate of this disease in some European nations is quite high, due to the presence of multiple prospective registries. On the other hand, few data-and in particular multicentre data-exist regarding this issue among Japanese subjects. Therefore, this study intends to assemble a multicentre registry that aims to comprehensively assess cardiovascular risk among Japanese FH patients while taking into account their genetic backgrounds. METHODS AND ANALYSIS: The Hokuriku-plus FH registry is a prospective, observational, multicentre cohort study, enrolling consecutive FH patients who fulfil the clinical criteria of FH in Japan from 37 participating hospitals mostly in Hokuriku region of Japan from April 2020 to March 2024. A total of 1000 patients will be enrolled into the study, and we plan to follow-up participants over 5 years. We will collect clinical parameters, including lipids, physical findings, genetic backgrounds and clinical events covering atherosclerotic and other important events, such as malignancies. The primary endpoint of this study is new atherosclerotic cardiovascular disease (ASCVD) events. The secondary endpoints are as follows: LDL cholesterol, secondary ASCVD events and the occurrence of other diseases including hypertension, diabetes and malignancies. ETHICS AND DISSEMINATION: This study is being conducted in compliance with the Declaration of Helsinki, the Ethical Guidelines for Medical and Health Research Involving Human Subjects, and all other applicable laws and guidelines in Japan. This study protocol has been approved by the Institutional Review Board at Kanazawa University. We will disseminate the final results at international conferences and in a peer-reviewed journal. TRIAL REGISTRATION NUMBER: UMIN000038210.

Genotypic and phenotypic features in homozygous familial hypercholesterolemia caused by proprotein convertase subtilisin/kexin type 9 (PCSK9) gain-of-function mutation.

BACKGROUNDS: Familial hypercholesterolemia (FH) is an autosomal dominant disease characterized by hypercholesterolemia, tendon xanthomas, and premature coronary heart disease. FH is caused by mutations of "FH genes," which include the LDL-receptor (LDLR), apolipoprotein B-100 (APOB) or proprotein convertase subtilisin/kexin type 9 (PCSK9). We evaluated the usefulness of FH gene analysis for diagnosing homozygous FH (homo-FH), particularly in cases caused by gain-of-function (g-o-f) mutations in PCSK9 (PCSK9 E32K). OBJECTIVES: To evaluate the frequency of homo-FH caused by PCSK9 E32K compared with FH due to other genetic causes and to report the phenotypic features of homo-FH caused by PCSK9 E32K. METHODS: Genomic DNA was prepared from white blood cells, and LDLR and PCSK9 mutations were identified using the Invader assay method. RESULTS: Of the 1055 hetero-FH patients, 62 patients (5.9%) carried the PCSK9 E32K mutation, while in the 82 alleles of 41 homo-FH patients, 13 (15.9%) had double mutations of LDLR allele and PCSK9 E32K mutation. Mean plasma total cholesterol (TC) (9.93 ± 2.95 mmol/L, mean ± SD) in true homo-FH cases with PCSK9 E32K or double hetero-FH cases with PCSK9 E32K and LDLR mutations were significantly lower than those in true homo-FH (18.06 ± 4.96 mmol/L) and compound heterozygous cases with LDLR mutations (14.84 ± 1.62 mmol/L). Mean plasma TC concentrations in the 59 hetero-FH cases with PCSK9 E32K (7.21 ± 1.55 mmol/L) were significantly lower than those (8.94 ± 1.53 mmol/L) in the hetero-FH by LDLR mutations. CONCLUSIONS: FH caused by PCSK9 g-o-f mutations is relatively common in Japan and causes a mild type of homo- and hetero-FH compared with FH caused by LDLR mutations.

Molecular genetic epidemiology of homozygous familial hypercholesterolemia in the Hokuriku district of Japan.

AIM: Familial hypercholesterolemia (FH) is caused by mutations of FH genes, i.e. LDL-receptor (LDLR), PCSK9 and apolipoprotein B (ApoB) gene. We evaluated the usefulness of DNA analysis for the diagnosis of homozygous FH (homo-FH), and studied the frequency of FH in the Hokuriku district of Japan. METHODS: Twenty-five homo-FH patients were recruited. LDLR mutations were identified using the Invader assay method. Mutations in PCSK9 were detected by PCR-SSCP followed by direct sequence analysis. RESULTS: We confirmed 15 true homozygotes and 10 compound heterozygotes for LDLR mutations. Three types of double heterozygotes for LDLR and PCSK9 were found. No FH patients due to ApoB mutations were found. The incidences of homo-FH and hetero-FH in the Hokuriku district were 1/171,167 and 1/208, respectively. CONCLUSIONS: Our observations underlined the value of FH gene analysis in diagnosing homo-FH and confirmed extraordinarily high frequency of FH in the Hokuriku district of Japan.

Identification of a novel missense mutation in the sterol 27-hydroxylase gene in two Japanese patients with cerebrotendinous xanthomatosis.

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive sterol storage disease caused by a mutated sterol 27-hydroxylase (CYP27A1) gene. We analyzed the CYP27A1 gene in two Japanese CTX patients. The CYP27A1 gene was amplified by PCR and screened by PCR-SSCP. The nucleotide sequence was analyzed to confirm mutations. Case 1 was a compound heterozygote for Arg104Gln in exon 2 and Arg441Gln in exon 8. To our knowledge, this is the first report in which the Arg104Gln mutation is identified in CTX patients. Probably case 2 would be a compound heterozygote for Arg441Trp in exon 8 and a mutation that was not identified.

Cholesterol efflux from J774 macrophages and Fu5AH hepatoma cells to serum is preserved in CETP-deficient patients.

BACKGROUND: The role of CETP in the development of atherosclerosis is debatable, and few data exist regarding the total impact of CETP inhibition on cholesterol efflux. METHODS: Acceptor capacities of whole serum and HDL subfractions separated by HPLC were compared using 2 different cell systems. Subjects with CETP deficiency (2 homozygous, 1 compound heterozygous, and 5 heterozygous) were analyzed along with 10 normolipidemic controls. The fractional efflux from cholesterol-labeled Fu5AH hepatoma cells was determined to be SR-BI mediated. The efflux difference between control and liver X receptor (LXR) agonist-induced ABCA1-upregulated J774 macrophages was considered as a measure of ABCA1-mediated efflux. RESULTS: For the Fu5AH cell system, the total acceptor capacities of whole serum and HPLC-separated HDL fraction 2 obtained from the homozygous subjects were 38% and 116% higher than the corresponding values for the controls, respectively (p<0.05). For the J774 cell system, the total acceptor capacities of whole serum and HPLC-separated HDL fractions were similar among the CETP-deficient subjects and controls. CONCLUSIONS: Serum from homozygous subjects with CETP-null defects exhibited enhanced acceptor capacity via an SR-BI dependent pathway, which is regulated by the middle HPLC-separated HDL fraction. Further, the cholesterol acceptor capacity of serum obtained from patients having complete and partial CETP deficiency was preserved via an ABCA1-dependent pathway.

Marked aortic valve stenosis progression after receiving long-term aggressive cholesterol-lowering therapy using low-density lipoprotein apheresis in a patient with familial hypercholesterolemia.

In 1982, a 49-year-old Japanese woman had been referred to our hospital for further investigation of her hypercholesterolemia. She was diagnosed as heterozygous familial hypercholesterolemia, because of Achilles tendon xanthoma and a family history of primary hypercholesterolemia. Three years later, she had chest pain on effort and angina pectoris was diagnosed by coronary angiography. At that time, she underwent coronary artery bypass grafting surgery with 2 saphenous vein grafts (SVG). Because more aggressive cholesterol-lowering therapy was needed for secondary prevention of coronary artery disease (CAD), weekly low-density lipoprotein (LDL) apheresis was started postoperatively, combined with drug therapy. Since 1986, her serum total cholesterol levels before and after LDL apheresis remained approximately 200 mg/dl and 90 mg/dl, respectively. Although her coronary sclerosis, including the SVG, did not progress appreciably for a period of 20 years, stenotic changes of the aortic valve developed rapidly at age 70, leading to aortic valve replacement surgery in 2005 at age 72. These findings suggest that careful attention to the progression of aortic valve stenosis is needed for extreme hypercholesterolemic patients even under optimal cholesterol-lowering therapy for the secondary prevention of CAD.

The lysophospholipid mediator sphingosine-1-phosphate promotes angiogenesis in vivo in ischaemic hindlimbs of mice.

AIMS: The lysophospholipid mediator sphingosine-1-phosphate (S1P) acts on vascular endothelial cells to stimulate migration, proliferation, and capillary-like tube formation in vitro. It is unknown whether S1P stimulates in vivo angiogenesis induced under tissue ischaemia. We investigated the effects of both exogenously and endogenously overproduced S1P on post-ischaemic angiogenesis in murine hindlimbs. METHODS AND RESULTS: The effects of locally injected S1P on blood flow recovery, angiogenesis, and vascular permeability in mouse ischaemic hindlimbs that underwent femoral arteriectomy were assessed by a laser Doppler blood flow (LDBF) analysis, anti-CD31 immunohistochemistry, and Miles assay, respectively, and compared with those induced by fibroblast growth factor (FGF)-2. Blood flow recovery and angiogenesis in sphingosine kinase 1-transgenic mice that overproduce S1P endogenously were also assessed and compared with wild-type mice. The LDBF analysis showed that daily intramuscular administration of S1P dose-dependently stimulated blood flow recovery, resulting in up to twice as much blood flow when compared with vehicle control, which was accompanied by 1.7-fold increase in the capillary density. The optimal S1P effects were comparable with those obtained with FGF-2. S1P injection did not increase vascular permeability. The post-ischaemic blood flow recovery and angiogenesis were accelerated in sphingosine kinase 1-transgenic mice, which showed 40-fold higher sphingosine kinase activity and 1.8-fold higher S1P content in skeletal muscle than in wild-type (WT) mice, without an increase in the vascular permeability when compared with WT mice. CONCLUSION: These results indicate that either local exogenous S1P administration or endogenous S1P overproduction promotes post-ischaemic angiogenesis and blood flow recovery. These observations suggest potential therapeutic usefulness of S1P for tissue ischaemia.

Cholesterol-years score is associated with development of senile degenerative aortic stenosis in heterozygous familial hypercholesterolemia.

We retrospectively evaluated the frequency and identified the factors associated with the development of aortic stenosis (AS) in 96 patients with heterozygous familial hypercholesterolemia (FH). The frequency of AS was 31% (4/13) and that of critical stenosis was 15% (2/13) in older patients over the age of 70 years. All 4 patients with AS were female aged more than 70 years who were diagnosed with FH when aged more than 60 years. There were no significant differences in conventional coronary risk factors; however, the age at cardiac catheterization, age at diagnosis of FH and the cholesterol-years score (CYS) with AS were significantly higher than those without AS (p=0.006, p=0.017, p=0.021, respectively). In multiple regression analysis, CYS was a significant independent predictor for the development of AS (p=0.037) in 13 older patients over the age of 70 years. These results suggest that physicians should be aware that AS needs attention in older patients with heterozygous FH, especially women who have been diagnosed late in life and those who have been inadequately treated.

Type III hyperlipoproteinemia exaggerated by Sheehan's syndrome with advanced systemic atherosclerosis: a 28-year clinical course.

A 38-year-old Japanese woman was admitted to hospital for further examination of systemic xanthomas. She had a past history of genital bleeding during her third delivery at the age of 21 years. She was diagnosed with Sheehan's syndrome. Her serum total cholesterol and triglyceride concentrations were 500 and 898 mg/dl, respectively. She was also diagnosed as having type III hyperlipoproteinemia on the basis of the presence of a broad-beta-band on agarose gel electrophoresis and extremely high concentrations of very-low-density lipoprotein cholesterol (310 mg/dl). The diagnosis was later confirmed by her apolipoprotein E isoforms (E2/E2) and genotypes (epsilon2/epsilon2). Thyroid and corticosteroid hormone replacement therapy cured the xanthomas, but also elevated her blood pressure. The serum concentration of intermediate-density lipoprotein cholesterol was consistently high, whereas that of low-density lipoprotein cholesterol was relatively low during the follow-up. Coronary atherosclerosis had already developed by the age of 38 years, and progressed significantly over the following 28 years. Severe stenotic lesions were observed in the bilateral renal arteries and carotid arteries, and in the abdominal aorta when she was 66 years old. These findings suggest that the continuous elevation of intermediate-density lipoprotein cholesterol for a long period contributed to the development of the atherosclerotic lesions.

Association of coronary artery ectasia with plasma insulin levels in Japanese men of heterozygous familial hypercholesterolemia with the low-density lipoprotein receptor gene mutation K790X.

BACKGROUND: Hyperinsulinemia is widely believed to be an important coronary risk factor. We investigated the effect of plasma insulin levels on the development of coronary ectasia in Japanese men with heterozygous familial hypercholesterolemia (FH). METHODS: A cross-sectional study was conducted in 20 FH men with the LDL receptor mutation (K790X) [age 42.3+/-2.8 years old, body mass index (BMI) 24.6+/-0.7 kg/m2, total cholesterol (TC) 8.68+/-0.36 mmol/l, triglycerides (TG) 1.76+/-0.23 mmol/l, high-density lipoprotein cholesterol (HDL-C) 0.977+/-0.065 mmol/l]. Subjects with diabetes mellitus were excluded. Plasma insulin levels, either fasting or during oral glucose tolerance test, were compared between subjects with and without coronary artery ectasia. RESULTS: FH subjects with coronary ectasia had significantly higher fasting plasma insulin levels than those without (12.6+/-1.4 vs. 7.7+/-0.5 mU/l; p<0.05). Also, plasma insulin levels during oral glucose tolerance test tended to be higher in the former than in the latter. CONCLUSIONS: Plasma insulin level could be an important determinant of the development of coronary artery ectasia in Japanese heterozygous FH men.

Efficacy of colestimide coadministered with atorvastatin in japanese patients with heterozygous familial hypercholesterolemia (FH).

BACKGROUND: Colestimide, a 2-methylimidazole-epichlorohydrin polymer, is a new bile-acid-sequestering resin, that is 4-fold as powerful at lowering low-density lipoprotein cholesterol (LDL-C) as the conventional resin (cholestyramine). Moreover, colestimide has excellent patient compliance because it is available in tablet form. METHODS AND RESULTS: The clinical efficacy of colestimide coadministered with atorvastatin on lipid and apolipoprotein concentrations was examined in 15 patients (M/F=10/5, mean+/-SE age=54+/-9 years) with heterozygous familial hypercholesterolemia (FH). After a period of wash-out of any lipid-lowering drugs, atorvastatin (20-40 mg) was administered to patients for at least 8 weeks, and then 3 g of colestimide was administered for a further 8 weeks. Total and LDL-C significantly (<0.0001) decreased by 35% from 361 to 233 mg/dl and 41% from 274 to 161 mg/dl, respectively. Addition of colestimide caused a further significant 12% and 20% reduction, respectively, from the initial values to 205 and 129 mg/dl, respectively. Colestimide was also effective in reducing serum LDL-C concentrations in heterozygous FH patients with hypertriglyceridemia (triglycerides>or=150 mg/dl). CONCLUSIONS: When monotherapy with atorvastatin is insufficient to treat severely hypercholesterolemic patients, such as those with heterozygous FH, colestimide acts to reinforce the action of statins.

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.

Long-term treatment with pitavastatin (NK-104), a new HMG-CoA reductase inhibitor, of patients with heterozygous familial hypercholesterolemia.

The clinical efficacy and safety of pitavastatin (NK-104), a novel HMG-CoA reductase inhibitor, during long-term treatment, were examined in 25 patients (male/female=11/14, mean age=53+/-13 (mean+/-SD) years) with heterozygous familial hypercholesterolemia (FH). After a period on placebo of >4 weeks, 2 mg/day of pitavastatin was administered for 8 weeks, and the dose was increased to 4 mg/day for up to 104 weeks. Total cholesterol (TC) decreased by 31% from the initial value of 340+/-57 to 237+/-40 mg/dl (P<0.0001) at week 8. During treatment with the higher dose, TC decreased even further to 212+/-35 mg/dl at week 12; it decreased by 37% from the initial value (P<0.0001). Similarly, the baseline low-density lipoprotein (LDL)-cholesterol (LDL-C) decreased by 41% at week 8, and by 49% at week 12, from 267+/-61 mg/dl at baseline. These findings indicate a dose-dependent effect of the drug on TC and LDL-C concentrations. To examine whether the levels of circulating matrix metalloproteinases (MMPs) and their endogenous inhibitors (tissue inhibitors of metalloproteinases: TIMPs) are altered during lipid-lowering therapy, we also measured their plasma levels. The mean levels of MMP-2 and -3 were significantly increased. No significant alteration was found in MMP-9, TIMP-1 and -2 levels. As for the safety of pitavastatin, adverse reactions were observed in one case (4%) of subjective and objective symptoms. The effects of pitavastatin on TC and LDL-C were stable during long treatment of patients with heterozygous FH.