Familial defective apolipoprotein B-100 is an autosomal dominant disorder characterized by hypercholesterolemia. It is caused by a mutation at position 3500 coding for the low-density lipoprotein (LDL) apo B-100 ligand. This impairs LDL clearance and subsequently results in hypercholesterolemia with an LDL predominance.

As an autosomal dominant disorder, familial defective apolipoprotein B-100 typically runs in families, although this diagnosis may not always be established within a family unit. Instead, there may be a high incidence of coronary artery disease or hypercholesterolemia in the family. It is estimated that approximately 0.08% of patients with hypercholesterolemia carry the defective LDL apo B-100 ligand.

Patients may be asymptomatic or can present with atherosclerotic cardiovascular events in early adulthood (third and fourth decades of life). Untreated, patients with hypercholesterolemia resulting from familiar defective apolipoprotein B-100 are at risk of early atherosclerotic cardiovascular events, such as stroke and myocardial infarction.