Russian patients with familial hypercholesterolemia (FH) were screened for pathogenic mutations using targeted next generation sequencing. Genetic testing was performed in 52 probands with definite or probable FH based on the Dutch lipid clinic network criteria (DLCN score ≥ 6). Blood samples were studied by massive parallel sequencing (Illumina HiSeq 1500 platform) using a custom capture library related to dyslipidemia and premature atherosclerosis. Mutations considered to be responsible for monogenic FH were identified in 48% of the probands: 24 with mutations in the LDLR gene and two with a mutation in the APOB gene. There were 22 pathogenic/likely pathogenic mutations in LDLR, eight of which have not been previously described in the literature. Four patients with a clinical picture of homozygous FH had two heterozygous LDLR mutations. Although mutation-negative patients had highly elevated total cholesterol and low-density lipoprotein cholesterol levels, only half of them had a family history of hypercholesterolemia. With respect to heterozygous FH, mutation-positive patients had higher maximum total cholesterol levels (p = 0.01), more severe carotid atherosclerotic lesions, and a higher percentage of premature peripheral artery disease (p = 0.03) than mutation-negative ones. However, the number of patients who suffered from myocardial infarction was similar between the two groups.

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Background Normally, von Willebrand factor (vWF) becomes highly reactive with platelets upon unfolding into a fibrillar conformation at critical shear rate (more than 5000 s–1), that may occur in stenotic arteries. At shear rates below critical value (1200–1300 s–1), which occur in intact coronary arteries, normally there is no conformational rearrangement of vWF. Pathologic unfolding of vWF at shear rates below critical value may increase a risk of the development of coronary thrombosis. There is little information on the role of shear stress induced conformational rearrangement of vWF in the development of myocardial infarction in young individuals. Purpose To investigate vWF-dependent platelet adhesion of patients with premature myocardial infarction at shear rates below critical value (1200–1300 s–1). Methods Using a microfluidic system, we measured platelet adhesion to a fibrinogen-coated optical surface at shear rates of 1200–1300 s–1 during 10 minutes. We assessed platelet-rich plasma of 8 male persons 40–52 years old, who had previous myocardial infarction at the age of 34–39. The control group comprised 6 healthy male volunteers 30–55 years old. We compared the intensity of scattered laser light measured in volts (V) at 10th minute. To study vWF-dependent platelet adhesion, we blocked GPIb receptor with monoclonal antibody to inhibit platelet interaction with vWF. To compare the intensity of vWF-dependent platelet adhesion with normally occurring adhesion to fibrinogen, we blocked GPIIb/IIIa receptor with monoclonal antibody. Results The inhibition of GPIb vWF-receptor decreased platelet adhesion to fibrinogen surface at shear rates of 1200–1300 s–1 by 17.8±4.7% in healthy volunteers and by 92±2.8% in persons with premature myocardial infarction (p<0.05). Inhibition of GPIIb/IIIa receptor decreased platelet adhesion by 91.5±3.8% in healthy volunteers and by 97.3±3.2% in persons with premature myocardial infarction. Conclusion Pathologic unfolding of vWF at shear rates below critical value may be involved in the development of premature myocardial infarction. Acknowledgement/Funding This work was supported by the grant of the Russian Science Foundation (project #16-15-10098)

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