Types of Cardiovascular Disease » What is HoFH
What is HoFH
Homozygous FH (HoFH) occurs if you inherit FH from both parents and is much more severe. This form of FH is very rare, occurring in about 1 out of 160,000 to 1,000,000 people worldwide.
How is HoFH different from HeFH?
In short: a person with HoFH has two mutated genes. When a person has one of these mutated genes, they have HeFH. Two mutated genes greatly increase a person’s blood cholesterol level and the risk of a heart attack.
What genes can be mutated in HoFH?
There are three different genes that may be mutated in HoFH, with the most common gene codes for a protein called the LDL receptor. LDL receptors in the liver remove LDL-C from the blood, so if a person has a mutated gene for the LDL receptor, the level of LDL-C in their blood will increase. Additionally, genes that make other proteins, such as PCSK9 and apolipoprotein B (ApoB), may also be mutated and decrease the removal of LDL-C from the blood.
If a person has a mutated gene for any of these proteins, the level of cholesterol in her or her blood will increase.
How will I know if I have HoFH?
The higher the LDL-C, the more likely it is that a person has HoFH (LDL-C > 500 mg/dL). Other characteristics include:
- Xanthomas: Cholesterol under the skin or tendons. In children, they are often found in the buttocks or folds of skin. They can also be found on tendons of the ankles and hands.
- Corneal arcus: is a greyish-white ring of cholesterol around the iris
- Heart and blood vessel disease: caused by cholesterol plaque buildup
Family History is Very Important
If both parents have very high LDL-C and/or history of heart disease before the ages of 55-65, this may indicate that the parents have FH and can each pass a mutated gene to their child(ren).
When each parent has HeFH, by chance, 1 out of 4 of their children will have a normal cholesterol level
- 2 of 4 children will have HeFH
- 1 of 4 children will have HoFH.