What Are Genes?

Our DNA contains genes, and are responsible for making all the different proteins in your body. Each protein has a specific job. Changes to DNA are called variants. Some variants may cause disease (also known as mutations), whereas other variants may not.

What Is the Role of Genes In FCS?

There are at least six genes known to be associated with FCS, and most mutations occur in the LPL gene. This gene makes a protein called lipoprotein lipase, which helps break down fat in the blood. In people with FCS, a type of fat called triglyceride builds up in the body at very high levels, leading to health problems like pancreatitis.

Disease-causing variants in five other genes may also lead to FCS: APOA5, APOC2, GPD1, GPIHPB1, and LMF1. Research may find other genes linked to FCS in the future.

How Can Genetic Tests Help?

When there is a suspicion of FCS

Genetic testing for FCS can help you and your doctor find out whether you have FCS. If genetic testing shows that you do have FCS, then that would explain why you have certain health problems. It can also help your doctors know how to best treat you.

People Living with FCS

Genetic testing can help find the cause of your FCS in your genes. This might give you peace of mind and it may also help your family members, especially your siblings, to be able to find out if they too have FCS. It is important to know that genetic testing cannot take away a diagnosis of FCS.

The FCS Community

Most people with FCS have two mutations in one of the FCS-related genes. As more people receive a clinical diagnosis of FCS, the community, as well as its understanding of this rare disease, will continue to grow.

How Genes Are Inherited

For someone to have FCS, they must inherit two disease-causing variants, one variant from each parent. A disease-causing variant is a harmful genetic change (also called a mutation). People who have one mutation in an FCS gene are called carriers. The way FCS is passed down from parents to a child is called autosomal recessive inheritance.

The diagram above shows how FCS is inherited. When two parents are carriers, each child they have together has a:

1 in 4 (or 25%) chance to have FCS. This means the child has two mutations, one passed down from each parent.

1 in 2 (or 50%) chance to be a carrier of FCS. This means the child has one mutation and the child will not have FCS. They are more likely to have higher triglyceride levels.

1 in 4 (or 25%) chance to be unaffected. This means the child does not have FCS and is not a carrier.

NEXT: Deciding to Have a Genetic Test