About Familial Hypercholesterolemia Type B

Cholesterol has many important functions in the body. But too much cholesterol, specifically low-density lipoprotein (LDL) cholesterol, can clog arteries and raise the risk of heart attack, stroke and other forms of cardiovascular disease. Lifestyle factors like diet and exercise can affect cholesterol levels, but genetic factors play a part too. Some forms of inherited high cholesterol are caused by mutations in the genes that encode the proteins that help the body clear LDL cholesterol from the bloodstream. When a mutation occurs in the APOB gene, the condition is called familial hypercholesterolemia type B (also known as familial defective apolipoprotein B-100).

Genes vs. Environment Inherited forms of high cholesterol can be due to mutations in several different genes. This report is about mutations in APOB, which cause a condition known as familial hypercholesterolemia type B (FH type B, also known as familial defective apolipoprotein B-100). 23andMe reports data for three APOB mutations. You can still have an APOB mutation that could cause FH type B even if your data indicates that you are a non-carrier. Mutations in genes other than APOB (not reported here) can also cause inherited forms of high cholesterol. Regardless of your genotype, non-genetic factors such as your diet and exercise habits can affect your cholesterol levels. If you are concerned about cholesterol or cardiovascular disease, consult a medical professional.

A genetic counselor can help you understand more about your 23andMe reports and respond to your genetic health questions. 23andMe is collaborating with Informed Medical Decisions, Inc., to give you direct access to board-certified genetic counselors that have been specifically trained to guide you through your 23andMe results. Click here to learn more about their independent genetic counseling services.  

Familial Hypercholesterolemia Type B and Your Genes  

Mutations in the genes that encode the proteins that help the body clear LDL cholesterol from the bloodstream cause inherited forms of high cholesterol called familial hypercholesterolemia. Mutations in the APOB gene lead to a form of the condition known as familial hypercholesterolemia type B (FH type B, also known as familial defective apolipoprotein B-100).

Several mutations in the APOB gene have been identified. Overall, APOB mutations are estimated to occur in about one out of every thousand people with European ancestry. The frequency of mutations in this gene in other populations has not been well studied.

23andMe reports data for two mutations known to be associated with elevated LDL cholesterol: R3500Q and R3500W. R3500Q is found mainly in people with European ancestry. R3500W is found mainly in Asian populations.

Having one copy of a mutation in the APOB gene can lead to mildly elevated LDL cholesterol levels. Two copies of a mutation can increase levels even more. However, cholesterol levels vary widely in people with APOB mutations and are probably influenced by other factors, both genetic and non-genetic.

23andMe also reports data for another mutation, R3531C. 23andMe does not include R3531C in its determination of whether or not you are likely to have FH type B because evidence is controversial over whether this mutation causes elevated LDL cholesterol on its own, or only in combination with mutations in other familial hypercholesterolemia-related genes. Information on R3531C is, however, included in the table in the technical report so that you can share a more complete picture of your genetics with your health care professional.

You can still have an APOB mutation that could cause FH type B even if your data indicates that you are a non-carrier. Mutations in genes other than APOB (not reported here) can also cause inherited forms of high cholesterol. If you are concerned about cholesterol or cardiovascular disease, consult a medical professional. 


https://www.23andme.com/health/familial-hypercholesterolemia-typeB/ 
 
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41-45, F
Jul 11, 2010