Apolipoprotein polymorphisms and familial hypercholesterolemia

Are H1 and H3 haplotypes of endothelial protein C receptor (PROCR) an important factor in contracting COVID-19?

The development of cardiovascular disease shows increase after contracting coronavirus 2019 (COVID-19) disease and myocardial damage is observed in patients who have had the disease severely. The relationship between genetic cardiovascular risk factors with COVID-19 infection was investigated in our study. One hundred thirty-five patients, 27 of whom were COVID-19 (-) and 108 were COVID-19 (+) patients, were included in the study. Patients were divided into three groups ([COVID-19 [-], COVID-19 [+] asymptomatic, and COVID-19 [+] symptomatic + patients with pulmonary involvement]). Genetic cardiovascular risk factors were examined in blood samples taken from the patients with new generation sequencing analysis. In the clinical classification, there were no significant differences between the three groups in fibrinogen beta chain-455G>A, human platelet antigen 1 (HPA1b)/platelet receptor GPIIIa/(ITGB3) (HPA1a/b; GpIIIa; integrin beta 3 L33P), ACE I/D, AGT (M268T), AGTR1 (1166A>C), Apo E (E2/E3/E4) (rs7412, rs429358), eNOS (786T>C), eNOS (894G>T) genes (p > 0.05). However, significant differences were observed in PROCR H3 haplotype/G (endothelial protein C receptor gene [EPCR] 4600A>G [A3 haplotype]), PROCR H1 haplotype/C (EPCR 4678G>C [A1 haplotype]) genes (p < 0.05). When COVID-19 (+) and COVID-19 (-) groups were compared, it was observed that the infection was more common in people with PROCR H1 haplotype/C and PROCR H3 haplotype/G genotypes (p < 0.05). PROCR H1 and PROCR H3 haplotypes may be an important factor in contracting COVID-19 disease. In people with COVID-19 disease, revealing PROCR genetic differences and measuring sEPCR levels will be beneficial in the follow-up of the disease.

Screening of LDLR and APOB gene mutations in Mexican patients with homozygous familial hypercholesterolemia

BACKGROUND

Familial hypercholesterolemia (FH) is an autosomal dominant disorder that causes accumulation of serum low-density lipoprotein cholesterol and premature cardiovascular disease. It is mainly related to mutations in the LDLR gene. Homozygous FH (HoFH) patients have the most severe form of the disease accounting for a worldwide prevalence of 1:1,000,000. In Mexico, at least 5 cases of HoFH have been reported.

OBJECTIVE

The aim of this study was to describe the clinical, biochemical, and molecular data observed in patients with HoFH phenotype.

METHODS

We included 13 patients, belonging to 11 families, with clinical and biochemical diagnoses suggestive of HoFH. Molecular analyses of the LDLR and APOB genes were performed by means of polymerase chain reaction followed by Sanger sequencing.

RESULTS

The causal mutation of HoFH was found in 8 of 11 unrelated patients. Excepting 1, all were true homozygotes. Six different variants in LDLR were identified: c.-139delCTCCCCCTGC, p.Glu140Lys, p.Asp360His, p.Asn405Lys, p.Ala755Glyfs*7, and p.Leu759Serfs*6. Of these, p.Asp360His and p.Asn405Lys were detected for the first time in Mexico; p.Leu759Serfs*6 showed to be the most frequent (43.7% of the alleles 7/16), and c.-139delCTCCCCCTGC is a new variant located in the promoter region.

CONCLUSIONS

This work increases knowledge of biochemical and genetic features in Mexican patients with HoFH. A novel mutation in the LDLR gene promoter was detected: c.-139delCTCCCCCTGC, which possibly inhibits its expression.

Silencing human genetic diseases with oligonucleotide-based therapies

RNA interference is an endogenous mechanism present in most eukaryotic cells that enables degradation of specific mRNAs. Pharmacological exploitation of this mechanism for therapeutic purposes attracted a whole amount of attention in its initial years, but was later hampered due to difficulties in delivery of the pharmacological agents to the appropriate organ or tissue. Advances in recent years have to a certain level started to address this specific issue. Genetic diseases are caused by aberrations in gene sequences or structure; these particular abnormalities are in theory easily addressable by RNAi therapeutics. Sequencing of the human genome has largely contributed to the identification of alterations responsible for genetic conditions, thus facilitating the design of compounds that can address these diseases. This review addresses the currently on-going programs with the aim of developing RNAi and other antisense compounds for the treatment of genetic conditions and the pros and cons that these products may encounter along the way. The authors have focused on those programs that have reached clinical trials or are very close to do so.

Connections between apolipoprotein E genotypes and the development of cardiovascular diseases

Elevated plasma lipid level is one of the main risk factors for cardiovascular diseases, which are considered to be pimary causes of death. Apolipoprotein E plays a part in the lipid transport in the blood, thus polimophisms of that affect the lipid composition of the plasma. The three most common alleles of apolipoprotein E are e2, e3, e4. Out of the two non-wild type alleles, the e2 and e4, the latter was shown to play a role in the development of cardiovascular diseases and Alzheimer’s disease. Some studies mention the e2/e2 homozygote genotype as one of the causes of hyperlipoproteinemia type III. Besides lipid metabolism, apolipoprotein E also influences the manifestation of cardiovascular diseases through other biochemical pathways, therefore it is essential to explore the molecular background of these metabolic pathways. Orv. Hetil., 2012, 153, 2070–2076.

Early onset of coronary heart disease in a young woman with familial hypercholesterolemia: coronary findings and effect of short term treatment with high dose atorvastatin

We describe the case of a 22-year old woman affected by familial hypercholesterolemia, referred for chest pain and treated with angioplasty of left anterior descending coronary artery. Marked systemic inflammation associated with acute coronary syndrome was reduced by 1-month therapy with high dose atorvastatin.

APOE and FABP2 Polymorphisms and History of Myocardial Infarction, Stroke, Diabetes, and Gallbladder Disease

Dysfunctional lipid metabolism plays a central role in pathogenesis of major chronic diseases, and genetic factors are important determinants of individual lipid profiles. We analyzed the associations of two well-established functional polymorphisms (FABP2 A54T and APOE isoforms) with past and family histories of 1492 population samples. FABP2-T54 allele was associated with an increased risk of past history of myocardial infarction (odds ratio (OR) = 1.51). Likewise, the subjects with APOE4, compared with E2 and E3, had a significantly increased risk of past history myocardial infarction (OR = 1.89). The OR associated with APOE4 was specifically increased in women for past history of myocardial infarction but decreased for gallstone disease. Interactions between gender and APOE isoforms were also significant or marginally significant for these two conditions. FABP2-T54 allele may be a potential genetic marker for myocardial infarction, and APOE4 may exert sex-dependent effects on myocardial infarction and gallbladder disease.

Genetic cardiovascular risk factors and age-related macular degeneration

PURPOSE

To investigate the association between genetic cardiovascular risk factors and exudative age-related macular degeneration (AMD) in a White Austrian population.

METHODS

Seventy-five unrelated AMD patients and 75 unrelated healthy, sex- and age-matched control patients were genotyped for the following 19 single nucleotide polymorphisms (SNPs) in 14 different genes: blood coagulation factor V (FV) R506Q, factor II (prothrombin) G20210A and factor XIII (FXIII) V34L; 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T, A1298C; plasminogen activator inhibitor 1 (PAI-1) 4G/5G; endothelial protein C receptor (EPCR) 4600 A>G (A3 haplotype), 4678 G>C (A1 haplotype); apolipoprotein B (ApoB) R3500Q; apolipoprotein E (ApoE) E2/E3/E4; β-fibrinogen -455 G>A; human platelet antigen 1 (HPA1) a/b; angiotensin-converting enzyme (ACE) I/D; endothelial nitric oxide synthase (eNOS) 786 T>C, 894 G>T; lymphotoxin alpha (LTA) 804 C>A and 9p21 rs10757278. Genotyping was carried out by polymerase chain reaction (PCR) followed by reverse hybridization (CVD StripAssays; ViennaLab Diagnostics, Vienna, Austria).

RESULTS

No statistically significant association could be observed between AMD and the investigated genetic risk factors for cardiovascular disease (CVD). All factors seem to be uniformly distributed in the two groups of AMD patients and healthy controls. Two variables -β-fibrinogen: -455 G>A (p = 0.0786) and apolipoprotein E4 (p = 0.0636) - were not as far from association as the others.

CONCLUSION

Our data show that the 19 tested CVD risk markers do not play a significant role in AMD. β-Fibrinogen and apolipoprotein E4 should be examined in a larger cohort.

Familial hypercholesterolemia: the lipids or the genes?

Familial Hypercholesterolemia (FH) is a common cause of premature cardiovascular disease and is often undiagnosed in young people. Although the disease is diagnosed clinically by high LDL cholesterol levels and family history, to date there are no single internationally accepted criteria for the diagnosis of FH. Several genes have been shown to be involved in FH; yet determining the implications of the different mutations on the phenotype remains a hard task. The polygenetic nature of FH is being enhanced by the discovery of new genes that serve as modifiers. Nevertheless, the picture is still unclear and many unknown genes contributing to the phenotype are most likely involved. Because of this evolving polygenetic nature, the diagnosis of FH by genetic testing is hampered by its cost and effectiveness.

In this review, we reconsider the clinical versus genetic nomenclature of FH in the literature. After we describe each of the genetic causes of FH, we summarize the known correlation with phenotypic measures so far for each genetic defect. We then discuss studies from different populations on the genetic and clinical diagnoses of FH to draw helpful conclusions on cost-effectiveness and suggestions for diagnosis.

Bevacizumab-associated hyperlipoproteinemia type IIb in a patient with advanced invasive-ductal breast cancer

AIM

We report a case of bevacizumab-associated hyperlipoproteinemia in a patient with advanced breast cancer.

CASE SUMMARY

A 57-year-old woman with advanced invasive-ductal breast cancer was administered bevacizumab from March 2008 to February 2009. Pretreatment laboratory showed borderline hypercholesterolemia (5.1 mmol/L, 197 mg/dL) and normal triglycerides (1.3 mmol/L, 115 mg/dL). Three months on treatment with bevacizumab, both serum cholesterol (11.9 mmol/L, 460 mg/dL) and triglycerides (7.4 mmol/L, 655 mg/dL) increased substantially, and remained well above the normal range for a period of bevacizumab treatment. From March 2008 to August 2008, the patient also received anticancer treatment with liposomal doxorubicin that was stopped early due to hand-foot syndrome. No concurrent hyperlipidemic drugs have been taken by the patient at the time of bevacizumab treatment. In February 2009, bevacizumab was stopped and the patient went on to receive paclitaxel for hepatic tumor progression. By December 2009, both serum triglycerides (1.3 mmol/L, 115 mg/dL) and cholesterol (3.2 mmol/L, 123 mg/dL) had normalized.

DISCUSSION

This is the first published case of bevacizumab-associated hyperlipoproteinemia. By applying the Naranjo ADR probability scales, at least a possible relationship between hyperlipoproteinemia type IIb and bevacizumab in this patient is supported by the data (Naranjo score 4). No hyperlipidemic drugs were given concurrently with bevacizumab, and the serum cholesterol and triglycerides decreased quickly after bevacizumab was discontinued.

CONCLUSIONS

This study describes a case of bevacizumab-associated hyperlipidemia. Patients receiving bevacizumab should have their cholesterol and triglycerides checked for potential worsening.

Joint linkage and segregation analysis under multiallelic trait inheritance: simplifying interpretations for complex traits

Identification of the genetic basis of common traits may be hindered by underlying complex genetic architectures that are inadequately captured by existing models, including both multiallelic and multilocus modes of inheritance (MOI). One useful approach for localizing genes underlying continuous complex traits is the joint oligogenic linkage and segregation analysis implemented in the package Loki. The method uses reversible jump Markov chain Monte Carlo to eliminate the need to prespecify the number of quantitative trait loci (QTLs) in the trait model, thus providing posterior distributions for the number of QTLs in a Bayesian framework. The current implementation assumes QTLs are diallelic, and therefore can overestimate the number of linked QTLs in the presence of a multiallelic QTL. To address the possibility of multiple alleles, we extended the QTL model to allow for a variable number of additive alleles at each locus. Application to simulated data shows that, under a diallelic MOI, the multiallelic and diallelic analysis models give similar results. Under a multiallelic MOI, the multiallelic analysis model provides better mixing and improved convergence, and leads to a more accurate estimate of the underlying trait MOI and model parameter values, than does the diallelic model. Application to real data shows the multiallelic model results in fewer estimated linked QTLs and that the predominant QTL model is similar to one of two predominant models estimated from the diallelic analysis. Our results indicate that use of a multiallelic analysis model can lead to better understanding of the genetic architecture underlying complex traits.