Familial hypercholesterolemia: Analysis of homozygous and heterozygous types and lipid management

Dyslipidemia, a serious concern in adults: The prevalence of dyslipidemia is extremely high and widespread, and it is gradually increasing with improved living standards. In the United States, approximately half of adults have unsatisfactory blood lipid levels. Recent surveys in China show that about 23.5% of adults over 35 years of age have blood cholesterol levels exceeding 5.2 mmol/L (200 mg/dL), a prevalence comparable to hypertension.

Familial hyperlipidemia: Some types of hyperlipidemia have a clear genetic predisposition and exhibit familial aggregation; this type of hyperlipidemia is called familial hyperlipidemia.

Currently, the genetic defects of a few cases of familial hyperlipidemia are partially understood, but the genetic defects of most cases remain unclear.

Common types of familial hyperlipidemia include familial hypercholesterolemia, familial hypertriglyceridemia, familial mixed hyperlipidemia, and familial dysbenolipoproteinemia.

Familial hypercholesterolemia: Familial hypercholesterolemia is an autosomal dominant inherited disorder, also known as type II hyperbeta-lipoproteinemia. It is primarily caused by a gene defect leading to the absence or abnormality of low-density lipoprotein receptors on cell membranes, resulting in abnormal low-density lipoprotein metabolism and significantly elevated plasma total cholesterol and low-density lipoprotein cholesterol levels. It may be accompanied by elevated triglycerides and often presents clinically as xanthelasma in multiple sites and early-onset coronary heart disease.

Based on the number of low-density lipoprotein receptors, it is divided into homozygous familial hypercholesterolemia and heterozygous familial hypercholesterolemia.

Homozygous familial hypercholesterolemia: Homozygous familial hypercholesterolemia is extremely rare clinically, with an incidence of only 1 in 1,000,000. Because they inherit an abnormal low-density lipoprotein receptor gene from each of their parents, they have little or no functional low-density lipoprotein receptors in their bodies. Consequently, their plasma cholesterol levels are 6-8 times higher than normal, leading to early onset of atherosclerosis. Symptoms and signs of coronary heart disease often appear as early as age 10, and some even die from myocardial infarction as young as age 3. Without effective treatment, these patients rarely live to 30.

Heterozygous familial hypercholesterolemia: Heterozygous familial hypercholesterolemia is not uncommon clinically.