The Mystery of Hypercholesterolemia in the Family

Hypercholesterolemia is caused by higher levels of low-density lipoprotein (LDL) cholesterol, which makes it more difficult for blood to flow through the organism due to the abnormal deposition of cholesterol in the walls of arteries. This condition increases the risk of heart attacks and cardiovascular diseases.

Hypercholesterolemia is a trait inherited in an autosomal dominant pattern, meaning that heterozygous individuals can suffer from this disease. A mutation in the LDL receptor gene localized on chromosome 19 has been identified as the most common genetic cause of hypercholesterolemia. This gene is responsible for the physiological removal of LDL from the bloodstream.

Donna and Darren have three children. In spite of Darren not having high cholesterol, two out of his three children have hypercholesterolemia, an inherited disease. Even though hypercholesterolemia is typically an autosomal dominant condition, not everyone who carries the gene will express it. This is due to a genetics concept known as 'variable expressivity,' which means that the gene's effects can vary among individuals.

In Darren's case, he carries the gene for hypercholesterolemia but doesn't express it. However, this gene has been passed onto two of his children, who do show high cholesterol levels. To help Darren understand better, we can compare it to seeds of a flower - all seeds have the potential to grow into a flower, but not all do. Similarly, Darren's gene for hypercholesterolemia was 'inactive' in him but 'active' in two of his children.