Phenotypic variability in 4 homozygous familial hypercholesterolemia siblings compound heterozygous for LDLR mutations

Pediatrics cascade screening in inherited dyslipidemias: a lipoprotein apheresis center experience

Familial hypercholesterolemia (FH) is less rare than one might think and, despite highly effective lipid-lowering therapies (LLT), more than half of the patients treated do not reach the lipid target indicated by the guidelines. In these patients, lipoprotein apheresis (LA) is the most effective tool to lowering apo-B containing atherogenic lipoproteins. In own center, since 1994, thanks to routinely cascade testing performed in patients who start LA, we have identified a pediatric population (30 subjects) that we analyzed retrospectively. Cascade screening, performed in subject with premature cardiovascular events or inherited dyslipidemias, is an effective approach to identified pediatric FH, a condition that pediatricians should also be aware. A dedicate network is required to investigate the involved genetic mutations and to set up a management program, including lipoprotein (a) measurement and subclinical atherosclerosis evaluation. Moreover, it is important that medical staff use a therapeutic pathway to help patients overcome discomfort associated with disease and chronic LLT, as well as improve adherence to lipid-lowering drugs.

Women and lipoprotein apheresis: another side of gender medicine

AIM

In heterozygous Familial Hypercholesterolemia (FH) woman atherosclerotic cardiovascular disease occurs 20-years earlier respect woman without FH while homozygous FH women may suffer from atherosclerotic cardiovascular disease even in childhood. Lipoprotein apheresis, a therapeutic "last chance saloon", is a well-tolerated procedure that markedly lowers LDL-cholesterol and Lp(a) levels in patients who do not achieve acceptable levels with maximal lifestyle and drug therapy.

METHODS AND RESULTS

The experience of LA treatment in 3 female homozygous FH patients was described. Moreover, an explore analysis on pre and post-LA hormonal levels was performed in 8 HeFH women showing a significant improvement in the atherogenic lipid profile (total cholesterol -56%, LDL cholesterol -71%, triglycerides -72%, Apo B lipoprotein -69%, Lp(a) -59%;) and a reduction of FSH and LH values (FSH - 28%, LH -31%).

CONCLUSIONS

Women with FH experience specific barriers to care, including underrepresentation in research, significant underestimation of risk, and discontinuation of therapy during pregnancy. Therefore, in this study, we investigated the possible effects of LA treatment on plasma FSH and LH levels.

Autosomal recessive hypercholesterolemia: Case report

INTRODUCTION

Autosomal recessive hypercholesterolemia (ARH; OMIM #603813) is a very rare monogenic disorder affecting less than 1 in 1000,000 people and is characterized by very high levels of low-density lipoprotein cholesterol (LDL-C), leading to aggressive and premature atherosclerotic cardiovascular disease if left untreated. Lowering of LDL-C is the main target of the treatment. We report on a 29-year-old male patient born in nonconsanguineous Lithuanian family homo(hemi-)zygous for LDLRAP1 gene variant causing ARH. This variant is not present in population databases and, to our knowledge, has not been reported in scientific literature before.

METHODS AND RESULTS

The earliest clinical sign, noticed at the age of 5 years, was painful and enlarging nodules on Achilles tendons. At the age of 10 years, xanthomas of the metacarpal joint area on both hands emerged. The first lipid panel was performed at the age of 12 years. In accordance with Dutch Lipid Clinic Network diagnostic criteria for familial hypercholesterolemia (FH), definite FH (type IIA hyperlipoproteinemia) was diagnosed and the treatment with cholestyramine 4 grams per day was initiated. As the patient was 15 years old, direct adsorption of low-density lipoprotein apheresis was started and repeated monthly. At the age of 20 years, along with lipoprotein apheresis, 10 mg of rosuvastatin daily intake was prescribed. At the age of 28 years, the dose of rosuvastatin was increased to 40 mg per day, and 10 mg of ezetimibe daily intake was added. At the age of 28 years, homozygous LDLRAP1 gene variant NM_015627.2:c.488A>C, NP_056442.2:p.(Gln163Pro) causing autosomal recessive hypercholesterolemia was determined by genetic testing.

CONCLUSIONS

This case report implies that ARH, being an extremely rare disorder, is a severe disease. As there is limited routine testing, including genetic testing, patients suffering from both this disease and FH may remain undiagnosed. Cascade screening and genetic counseling differ for ARH as compared with FH, as the carrier of a pathogenic variant in the LDLRAP1 gene does not have marked total cholesterol and LDL-C elevations. However, genetic testing of the proband and their relatives is essential to evaluate the risk of development of FH and to provide prognosis as well as adequate, timely treatment. To improve the quality of life of patients with FH and prolong their life expectancy, national registries of FH and wider laboratory and genetic testing are undoubtedly necessary. A national FH screening program was set up in Lithuania, which helps to identify, monitor, and treat subjects with FH.

In search of a genetic explanation for LDLc variability in an FH family: common SNPs and a rare mutation in MTTP explain only part of LDL variability in an FH family

We previously identified a highly consanguineous familial hypercholesterolemia (FH) family demonstrating segregation of the JD Bari mutation in the LDL receptor as well as a putative cholesterol-lowering trait. We aimed to identify genes related to the latter effect. LDL cholesterol (LDLc) values were normalized for FH affectation status, age, and gender. Using genome-wide SNP data, we examined whether known SNPs gleaned from a genome-wide association study could explain the variation observed in LDLc. Four individuals with markedly reduced LDL levels underwent whole exome sequencing. After prioritizing all potential mutations, we identified the most promising candidate genes and tested them for segregation with the lowering trait. We transfected a plasmid carrying the top candidate mutation, microsomal triglyceride transfer protein (MTTP) R634C, into COS-7 cells to test enzymatic activity. The SNP score explained 3% of the observed variability. MTTP R634C showed reduced activity (49.1 nmol/ml) compared with the WT allele (185.8 nmol/ml) (P = 0.0012) and was marginally associated with reduced LDLc in FH patients (P = 0.05). Phenotypic variability in a FH pedigree can only partially be explained by a combination of common SNPs and a rare mutation and a rare variant in the MTTP gene. LDLc variability in FH patients may have nongenetic causes.

Heterozygous familial hypercholesterolaemia in a pair of identical twins: a case report and updated review

BACKGROUND

Familial hypercholesterolaemia (FH) is the most common inherited metabolic disease with an autosomal dominant mode of inheritance. It is characterised by raised serum levels of total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-c), leading to premature coronary artery disease. Children with FH are subjected to early and enhanced atherosclerosis, leading to greater risk of coronary events, including premature coronary artery disease. To the best of our knowledge, this is the first report of a pair of monochorionic diamniotic identical twins with a diagnosis of heterozygous FH, resulting from mutations in both LDLR and ABCG8 genes.

CASE PRESENTATION

This is a rare case of a pair of 8-year-old monochorionic diamniotic identical twin, who on family cascade screening were diagnosed as definite FH, according to the Dutch Lipid Clinic Criteria (DLCC) with a score of 10. There were no lipid stigmata noted. Baseline lipid profiles revealed severe hypercholesterolaemia, (TC = 10.5 mmol/L, 10.6 mmol/L; LDL-c = 8.8 mmol/L, 8.6 mmol/L respectively). Their father is the index case who initially presented with premature CAD, and subsequently diagnosed as FH. Family cascade screening identified clinical FH in other family members including their paternal grandfather who also had premature CAD, and another elder brother, aged 10 years. Genetic analysis by targeted next-generation sequencing using MiSeq platform (Illumina) was performed to detect mutations in LDLR, APOB100, PCSK9, ABCG5, ABCG8, APOE and LDLRAP1 genes. Results revealed that the twin, their elder brother, father and grandfather are heterozygous for a missense mutation (c.530C > T) in LDLR that was previously reported as a pathogenic mutation. In addition, the twin has heterozygous ABCG8 gene mutation (c.55G > C). Their eldest brother aged 12 years and their mother both had normal lipid profiles with absence of LDLR gene mutation.

CONCLUSION

A rare case of Asian monochorionic diamniotic identical twin, with clinically diagnosed and molecularly confirmed heterozygous FH, due to LDLR and ABCG8 gene mutations have been reported. Childhood FH may not present with the classical physical manifestations including the pathognomonic lipid stigmata as in adults. Therefore, childhood FH can be diagnosed early using a combination of clinical criteria and molecular analyses.

ANGPTL3: a novel biomarker and promising therapeutic target

Angiopoietin-like protein 3 (ANGPTL3) belongs to a multifunctional secreted protein that mainly expresses in the liver, and is regulated by numerous post-translational modifications, including multiple cleavage and glycosylation. Accumulating evidences have revealed that ANGPTL3 plays a critical role in both biological processes, such as lipid metabolism, angiogenesis and haematopoietic function and pathological changes, including atherosclerosis, carcinogenesis, nephrotic syndrome, diabetes, liver diseases and so on. Thus, ANGPTL3 may serve as a potential biomarker in these diseases. Furthermore, ANGPTL3 signalling pathways including LXR/ANGPTL3, thyroid hormone/ANGPTL3, insulin/ANGPTL3 and leptin/ANGPTL3 are also involved in physiological and pathological processes. Some biological ANGPTL3 inhibitors, chemical drugs and traditional Chinese medicine exert beneficial effects by targeting ANGPTL3 directly or indirectly. Therefore, elucidating the effects and underlying mechanisms of ANGPTL3 is essential to develop promising strategies in the diagnosis and treatment of related diseases.