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.

Detailed analysis of serum lipids and lipoproteins from Japanese type III hyperlipoproteinemia with apolipoprotein E2/2 phenotype.

BACKGROUND: To clarify a detailed profile of serum lipids, lipoproteins and apolipoproteins (apo) in type III hyperlipoproteinemia (HLP) with apolipoprotein E (apo E) phenotype 2/2. METHODS: Nineteen consecutive Japanese type III HLP (9 men, 10 women) were studied. All had hypertriglyceridemia and 74% showed hypercholesterolemia. RESULTS: The degree of hyperlipidemia [total cholesterol (TC) 8.1 +/- 3.2 mmol/l, triglycerides (TG) 5.2 +/- 2.9 mmol/l] was milder than that in type III HLP in western countries. Lipoprotein fractions analyzed by ultracentrifugation showed that very low density lipoprotein cholesterol (VLDL-C) concentrations were considerably increased and that intermediate density lipoprotein cholesterol (IDL-C) concentrations were also increased, whereas low-density lipoprotein cholesterol (LDL-C) concentrations were low. Serum apo A-I, A-II and B concentrations were not increased, while apo C-II, C-III and E concentrations were considerably increased. However, the increase of apo E concentrations in the study subjects was far more pronounced than that of apo C-III, causing the ratio of apo E/C-III to be considerably higher than hyperlipidemia with other apo E phenotypes. CONCLUSION: By using this index apo E/C-III, it is possible to segregate type III HLP with apo E2/2 phenotype from other types of hyperlipidemia.

Identification of two novel missense mutations (p.R1221C and p.R1357W) in the ABCC6 (MRP6) gene in a Japanese patient with pseudoxanthoma elasticum (PXE).

Pseudoxanthoma elasticum (PXE) is a rare, inherited, systemic disease of elastic tissue that in particular affects the skin, eyes, and cardiovascular system. Recently, the ABCC6 (MRP6) gene was found to cause PXE. A defective type of ABCC6 gene (16pl3.1) was determined in two Japanese patients with PXE. In order to determine whether these patients have a defect in ABCC6 gene, we examined each of 31 exons and flanking intron sequences by PCR methods (SSCP screening and direct sequencing). We found two novel missense variants in exon 26 and 29 in a compound heterozygous state in the first patient. One is a missense mutation (c.3661C>T; p.R1221C) in exon 26 and the other is a missense mutation (c.4069C>T; p.R1357W) in exon 29. These mutations have not been detected in our control panel of 200 alleles. To our knowledge, this is the first report of mutation identification in the ABCC6 gene in Japanese PXE patients. The second patient was homozygous for 2542_2543delG in ABCC6 gene and heterozygous for 6 kb deletion of LDL-R gene. This case is the first report of a genetically confirmed case of double mutations both in PXE and FH loci.