HeFH

HeFH refers to Heterozygous Familial Hypercholesterolemia. It is a common genetic disorder characterized by very high levels of low-density lipoprotein (LDL) cholesterol, often called "bad" cholesterol, in the blood from birth. This condition is inherited in an autosomal dominant pattern, meaning that inheriting just one copy of the altered gene from either parent is enough to cause the condition. HeFH affects approximately 1 in 200 to 1 in 300 people worldwide.

The underlying cause of HeFH is typically a mutation in one of several genes responsible for removing LDL cholesterol from the bloodstream. The most common genes affected are LDLR (encoding the LDL receptor), APOB (encoding apolipoprotein B), and PCSK9. When these genes are not functioning correctly, LDL cholesterol builds up in the arteries.

Individuals with HeFH often have significantly elevated LDL cholesterol levels, typically ranging from 190 mg/dL to over 400 mg/dL, compared to average levels below 130 mg/dL. This chronic elevation of LDL cholesterol dramatically increases the risk of premature cardiovascular disease, including heart attacks and strokes, often occurring at much younger ages than in the general population. Physical signs can include xanthomas (fatty deposits under the skin) and xanthelasmas (cholesterol deposits around the eyes), although these are not always present. Diagnosis is usually made through a combination of blood tests measuring lipid levels and a family history of high cholesterol or premature heart disease.