I Have An FAOD. Will My Child Have One Too?: Genetics of FAODs
For many future parents, their concerns for their children include trivial thoughts like, “I hope they don’t get my hair,” “I don’t want them to get my bad teeth,” “I hope they get my husband’s height.” What many of these parents don’t understand is that their future offspring have already likely won the gene pool jackpot. The idea of passing on their traits doesn’t include fears of passing on any serious disorders or life-threatening diseases. For parents who have a fatty acid oxidation disorder or FAOD, this process is a lot scarier and there is a lot more at risk.
The Heredity of FAODs
At the International Network for Fatty Acid Oxidation Research and Management (INFORM), we not only work with researchers in the field but also with parents of children with FAODs as well as the patients themselves.
Although rare, fatty acid oxidation disorders do have a genetic component to them, but genetics of FAODs are a fickle matter. We see parents who have never been diagnosed with one of these disorders have children who end up with one. We also see parents with one of these disorders like a carnitine uptake defect who have children who are fine. Statistically speaking, if you are a parent and you have a fatty acid oxidation disorder, then your biological child is more likely to have this disorder than a child with two parents without.
Parent(s) With FAODs
FAODs are typically the result of two recessive genes, so a child with the disorder will need to inherit one recessive gene from each parent. This means that both parents need to at least be carriers of the disorder.
If only one parent is a carrier, the child should be healthy and only has about a 50% chance of being a carrier themselves. If both parents are carriers, then the child has about a 25% chance of developing the disorder and a 25% chance of being a healthy carrier.
In the rare event that both parents happen to have the same FOD, then the child has an extremely high risk of getting this oxidation disorder as well. If you have been diagnosed with a fatty acid oxidation disorder and are looking to have a child, make sure you discuss this with your doctor. While there is a small chance your child will inherit the mutations to get the same disorder, you need to understand that the risk is still there.
Parents Who Are Carriers of FAODs
FAOD genetics are complicated. Because many fatty acid oxidation disorders involve recessive genes, many healthy people can be carriers of the disorder and never know it or exhibit any symptoms. Most children will get a fatty acid oxidation disorder because they got the recessive gene from both parents. If both parents are carriers, then there is a 25% chance that any child they have together will develop the disorder.
Sibling With An FAOD
If you have a child that is diagnosed with a fatty acid oxidation disorder, then it is wise to have their siblings checked for the disorder as well. Most FAODs are detected in the first few days of life with prenatal screening, but as with an ACAD9 deficiency, this is not the case. It is possible that a diagnosis was missed. Also, because one child already has this disorder, any biological sibling or future sibling has a higher chance of having this disorder.
If you are concerned about the genetics of fatty acid oxidation disorders and think there is a possibility your child will develop this disorder, you should look into genetic screening and ask an FAOD professional