A Chinese homozygote of familial hypercholesterolemia: identification of a novel C263R mutation in the LDL receptor gene

Evolving Concepts of the SCORE System: Subtracting Cholesterol from Risk Estimation: A Way for a Healthy Longevity?

The role of cholesterol, mainly low-density lipoproteins (LDL-C), as a causal risk factor for atherosclerotic cardiovascular disease (ASCVD) is now established and accepted by the international scientific community. Based on this evidence, the European and American guidelines recommend early risk stratification and "rapid" achievement of the suggested target according to the risk estimation to reduce the number of major cardiovascular events. Prolonged exposure over the years to high levels of LDL-C is one of the determining factors in the development and progression of atherosclerotic plaque, on which the action of conventional risk factors (cigarette smoking, excess weight, sedentary lifestyle, arterial hypertension, diabetes mellitus) as well as non-conventional risk factors (gut microbiota, hyperuricemia, inflammation), alone or in combination, favors the destabilization of the atherosclerotic lesion with rupture/fissuration/ulceration and consequent formation of intravascular thrombosis, which leads to the acute clinical manifestations of acute coronary syndromes. In the current clinical practice, there is a growing number of cases that, although extremely common, are emblematic of the concept of long-term exposure to the risk factor (LDL hypercholesterolemia), which, not adequately controlled and in combination with other risk factors, has favored the onset of major cardiovascular events. The triple concept of "go lower, start earlier and keep longer!" should be applied in current clinical practice at any level of prevention. In the present manuscript, we will review the current evidence and documents supporting the causal role of LDL-C in determining ASCVD and whether it is time to remove it from any score.

Impact of LDLR polymorphisms on lipid levels and atorvastatin's efficacy in a northern Chinese adult Han cohort with dyslipidemia

BACKGROUND

Dyslipidemia, a significant risk factor for atherosclerotic cardiovascular disease (ASCVD), is influenced by genetic variations, particularly those in the low-density lipoprotein receptor (LDLR) gene. This study aimed to elucidate the effects of LDLR polymorphisms on baseline serum lipid levels and the therapeutic efficacy of atorvastatin in an adult Han population in northern China with dyslipidemia.

METHODS

In this study, 255 Han Chinese adults receiving atorvastatin therapy were examined and followed up. The 3' untranslated region (UTR) of the LDLR gene was sequenced to identify polymorphisms. The associations between gene polymorphisms and serum lipid levels, as well as changes in lipid levels after intervention, were evaluated using the Wilcoxon rank sum test, with a P < 0.05 indicating statistical significance. Assessment of linkage disequilibrium patterns and haplotype structures was conducted utilizing Haploview.

RESULTS

Eleven distinct polymorphisms at LDLR 3' UTR were identified. Seven polymorphisms (rs1433099, rs14158, rs2738466, rs5742911, rs17249057, rs55971831, and rs568219285) were correlated with the baseline serum lipid levels (P < 0.05). In particular, four polymorphisms (rs14158, rs2738466, rs5742911, and rs17249057) were in strong linkage disequilibrium (r2 = 1), and patients with the AGGC haplotype had higher TC and LDL-C levels at baseline. Three polymorphisms (rs1433099, rs2738467, and rs7254521) were correlated with the therapeutic efficacy of atorvastatin (P < 0.05). Furthermore, carriers of the rs2738467 T allele demonstrated a significantly greater reduction in low-density lipoprotein cholesterol (LDL-C) levels post-atorvastatin treatment (P = 0.03), indicating a potentially crucial genetic influence on therapeutic outcomes. Two polymorphisms (rs751672818 and rs566918949) were neither correlated with the baseline serum lipid levels nor atorvastatin's efficacy.

CONCLUSIONS

This research outlined the complex genetic architecture surrounding LDLR 3' UTR polymorphisms and their role in lipid metabolism and the response to atorvastatin treatment in adult Han Chinese patients with dyslipidemia, highlighting the importance of genetic profiling in enhancing tailored therapeutic strategies. Furthermore, this investigation advocates for the integration of genetic testing into the management of dyslipidemia, paving the way for customized therapeutic approaches that could significantly improve patient care.

TRIAL REGISTRATION

This multicenter study was approved by the Ethics Committee of Xiangya Hospital Central South University (ethics number K22144). It was a general ethic. In addition, this study was approved by The First Hospital of Hebei Medical University (ethics number 20220418).

The distribution and characteristics of LDL receptor mutations in China: A systematic review

Familial hypercholesterolemia (FH) is a common and serious dominant genetic disease, and its main pathogenic gene is the low-density lipoprotein receptor (LDLR) gene. This study aimed to perform a systematic review of LDLR mutations in China. Using PubMed, Embase, Wanfang (Chinese), the Chinese National Knowledge Infrastructure (Chinese), and the Chinese Biological and Medical database (Chinese), public data were limited to December 2014. The Medical Subject Headings terms and the following key words were used: “familial hypercholesterolemia”, “Chinese”, “China”, “Hong Kong”, and “Taiwan”. A total of 74 studies including 295 probands with 131 LDLR mutations were identified. Most of the mutations were located in exon 4 of LDLR and approximately 60% of the mutations were missense mutations. Thirty new mutations that were not recorded in the LDLR databases were found. In silico analysis revealed that most of the mutations were pathogenic. The primary LDLR mutations were C308Y, H562Y, and A606T, and all of the mutations had functional significance. Prevalence data suggest that there are nearly 3.8 million FH patients in China, although reported numbers are much smaller, suggesting that FH is widely misunderstood. This systematic review provides information that is specific to China for inclusion in the international FH database.

Mutations in the LDL receptor gene in four Chinese homozygous familial hypercholesterolemia phenotype patients

BACKGROUND AND AIMS

Familial hypercholesterolemia (FH) is an autosomal dominant disorder of lipoprotein metabolism caused by mutations in the low-density lipoprotein receptor (LDL-R) gene, leading to elevated levels of cholesterol and an increased risk of coronary heart disease. In this article, from four homozygous FH phenotype probands we identified disease causing mutations and analyzed the relationship between genotype and phenotype.

METHODS AND RESULTS

DNA sequencing identified five LDL-R point mutations in four unrelated families. We found a novel homozygous mutation (C210R), a homozygous mutation at W462X, a compound heterozygous mutation of C122Y and T383I, and a G>A intron 3 splice site homozygous mutation. The functional alteration caused by the novel C210R mutation was confirmed by FACS analysis. Four probands have high low-density lipoprotein cholesterol (LDL-C) levels, ranging from 14.65 to 27.66 mmol/L. Their heterozygous parents had relatively low levels. B-mode ultrasound supplemented by Doppler was used to examine aortic/mitral valve structural alterations and carotid intima-media thickness (ITM) in all probands. The ITM values were between 1.2 and 2.3mm, much higher than the normal value of <0.8mm.

CONCLUSION

Our data demonstrated that all the probands were associated with severe hypercholesterolemia, thick carotid IMT and a low CFVR (coronary flow velocity reserve) value. The novel mutation (C120Y) is a disease causing mutation.

Identification and characterization of novel low-density lipoprotein receptor mutations of familial hypercholesterolaemia patients in Taiwan

BACKGROUND

Familial hypercholesterolaemia (FH) is an autosomal dominant disease associated with a very high risk of coronary vascular disease. The study objective was to identify patients with FH in Taiwan and characterize novel mutations.

MATERIALS AND METHODS

Fifty-one patients with suspected FH living in Taiwan were screened for mutations in both the low-density lipoprotein (LDL) receptor and the apolipoprotein (apoB) genes using the multiplex polymerase chain reaction and exon-by-exon DNA sequencing technique. Functional consequences on LDL receptor activity were characterized in vitro for novel mutations and family pedigree was also analyzed.

RESULTS

Thirteen different functional mutations in the LDL receptor gene and one mutation in the apoB gene were found in 21 patients. Among the 13 mutations in the LDL receptor gene, 10 were single-point missense mutations, one was a two-point mutation in the same allele, one was a non-sense mutation and one was a frame-shift mutation. There were three novel mutations, including two missense mutations (M510K and W512R) and one frame-shift mutation (1953 delTA mutation). The characterization of missense M510K retained 36.2% of the activity of the normal receptor. Conversely, frame-shift 1953 delTA and missense W512R led to defective proteins, with only 0-6% of normal receptor activity.

CONCLUSIONS

The study identified 13 LDL receptor gene mutations and characterized three novel mutations causing FH in Taiwan. This facilitated a better understanding of FH among the Chinese population and may enable diagnosis of FH at the molecular level at a presymptomatic, early age.

Identification and characterization of LDL receptor gene mutations in hyperlipidemic Chinese

DNA screening for LDL receptor mutations was performed in 170 unrelated hyperlipidemic Chinese patients and two clinically diagnosed familial hypercholesterolemia patients. Two deletions (Del e3-5 and Del e6-8), eight point mutations (W-18X, D69N, R94H, E207K, C308Y, I402T, A410T, and A696G), and two polymorphisms (A370T and I602V) were identified. Of these mutations, C308Y and Del e6-8 were found in homozygosity, and D69N and C308Y were seen in unrelated patients. The effects of mutations on LDL receptor function were characterized in COS-7 cells. The LDL receptor level and activity were close to those of wild type in A696G transfected cells. A novel intermediate protein and reduction of LDL receptor activity were seen in D69N transfected cells. For R94H, E207K, C308Y, I402T, and A410T mutations, only approximately 20-64% of normal receptor activities were seen. Conversely, Del e3-5 and Del e6-8 lead to defective proteins with approximately 0-13% activity. Most of the mutant receptors were localized intracellularly, with a staining pattern resembling that of the endoplasmic reticulum and Golgi apparatus (D69N, R94H, E207K, C308Y, and I402T) or endosome/lysosome (A410T and Del e6-8). Molecular analysis of the LDL receptor gene will clearly identify the cause of the patient's hyperlipidemia and allow appropriate early treatment as well as antenatal and family studies.