LC-FAOD are rare, genetic metabolic disorders that prevent the body from breaking down long-chain fatty acids into energy during metabolism.
You may identify with a certain type of LC-FAOD:
CPT I (carnitine palmitoyltransferase I) deficiency
A mutation in the CPTIA gene causes the CPT I enzyme to not function properly, which results in CPT I deficiency. This means that long-chain fatty acids cannot begin the first step in the carnitine shuttle to bring long-chain fatty acids into the mitochondrion.
CACT (carnitine-acylcarnitine translocase) deficiency
A mutation in the SLC25A20 gene causes CACT deficiency. This means that the middle step of the carnitine shuttle, transporting the long-chain fatty acid into the mitochondrion, cannot be performed properly.
CPT II (carnitine palmitoyltransferase II) deficiency
A mutation in the CPT II gene causes CPT II deficiency. This means that the last step in the carnitine shuttle cannot be completed. Therefore, long-chain fatty acids cannot enter the mitochondrion.
VLCAD (very long-chain acyl-CoA dehydrogenase) deficiency
A mutation in the ACADVL gene causes VLCAD deficiency. This enzyme is part of the long-chain beta oxidation spiral. Once long-chain fatty acids enter the mitochondria after transportation via the carnitine shuttle, they are processed by the long-chain beta oxidation spiral. If the VLCAD enzyme is not functioning properly, then long-chain fatty acids are not broken down properly, resulting in lower energy and damage from incomplete processing of fatty acids.
TFP (trifunctional protein) deficiency
TFP deficiency occurs when a person has a mutation in both the HADHA gene and HADHB gene. TFP is a three enzyme complex and performs the last three steps in the breakdown of long-chain fatty acids. One of these enzymes is LCHAD. If the TFP enzyme complex is not working properly, long-chain fatty acids cannot be broken down for energy and unused fatty acids can build up in the body and cause issues.
LCHAD (long-chain 3-hydroxy-acyl-CoA dehydrogenase) deficiency
LCHAD deficiency occurs when a person has a mutation in the HADHA gene. This is part of the TFP complex (see TFP), but the mutation is just in the HADHA gene, causing LCHAD deficiency. If there is a deficiency in this step, long-chain fatty acids are not properly broken down so they cannot be used for energy.
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