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The early detection and treatment of familial hypercholesterolemia (FH) in childhood and adolescence are critical for increasing life expectancy. The purpose of our study was to investigate blood lipid parameters, features of physical signs of cholesterol accumulation, and a personal and family history of premature cardiovascular diseases in children and young adults when FH is diagnosed. The analysis included patients under 18 years of age (n = 17) and young adults (18-44 years of age; n = 43) who received a diagnosis of FH according to clinical criteria. Targeted high-throughput sequencing was performed using a custom panel of 43 genes. A family history of cardiovascular diseases was more often noted in the group under 18 years of age than in young adults ( p < 0.001). Among young adults, there was a high prevalence of typical signs of the disease such as tendon xanthomas and the early development of arterial atherosclerosis ( p < 0.001). By molecular genetic testing, "pathogenic" and "probably pathogenic" variants were identified in the genes of 73.3% of patients under 18 years of age and 51.4% of patients 18-44 years of age. Thus, blood lipid screening tests combined with an accurate assessment of the family history is a highly relevant and inexpensive option for diagnosing FH in childhood. Molecular genetic testing allows us to make an accurate diagnosis and to improve adherence to treatment.

The aim of this work was to identify genetic variants potentially involved in familial hypercholesterolemia in 43 genes associated with lipid metabolism disorders. Targeted high-throughput sequencing of lipid metabolism genes was performed (80 subjects with a familial-hypercholesterolemia phenotype). For patients without functionally significant substitutions in the above genes, multiplex ligation-dependent probe amplification was conducted to determine bigger mutations (deletions and/or duplications) in the LDLR promoter and exons. A clinically significant variant in some gene associated with familial hypercholesterolemia was identified in 47.5% of the subjects. Clinically significant variants in the LDLR gene were identified in 19 probands (73.1% of all variants identified in probands); in three probands (11.5%), pathogenic variants were found in the APOB gene; and in four probands (15.4%), rare, clinically significant variants were identified in genes LPL , SREBF1 , APOC3 , and ABCG5 . In 12 (85.7%) of 14 children of the probands, clinically significant variants were detectable in genes associated with familial hypercholesterolemia. The use of clinical criteria, targeted sequencing, and multiplex ligation-dependent probe amplification makes it possible to identify carriers of rare clinically significant variants in a wide range of lipid metabolism genes and to investigate their influence on phenotypic manifestations of familial hypercholesterolemia.

This review addresses the contribution of some genes to the phenotype of familial hypercholesterolemia. At present, it is known that the pathogenesis of this disease involves not only a pathological variant of low-density lipoprotein receptor and its ligands (apolipoprotein B, proprotein convertase subtilisin/kexin type 9 or low-density lipoprotein receptor adaptor protein 1), but also lipids, including sphingolipids, fatty acids, and sterols. The genetic cause of familial hypercholesterolemia is unknown in 20%-40% of the cases. The genes STAP1 (signal transducing adaptor family member 1), CYP7A1 (cytochrome P450 family 7 subfamily A member 1), LIPA (lipase A, lysosomal acid type), ABCG5 (ATP binding cassette subfamily G member 5), ABCG8 (ATP binding cassette subfamily G member 8), and PNPLA5 (patatin like phospholipase domain containing 5), which can cause aberrations of lipid metabolism, are being evaluated as new targets for the diagnosis and personalized management of familial hypercholesterolemia.