Carnitine uptake defect (CUD) is a rare genetic condition. CUD results from a mutation (error) in the SLC22A5 gene which codes for the protein OCTN2. Due to this mistake, people with CUD cannot use certain fats to make energy. Normally, fats are broken down by enzymes (special proteins) into fatty acids. Fatty acids must be taken into the mitochondria of the cell to make energy. Long chain fatty acids need to be attached to carnitine so they can be moved into the mitochondria. In CUD, there is not enough OCTN2, the protein which brings carnitine into our cells. Without carnitine in the cells, the long chain fatty acids cannot be moved. Fatty acids are the main energy for the heart and muscles and are an important during fasting (like sleeping) for the liver and other tissues. In addition, fatty acids will build up in the body and become toxic, damaging to the heart, liver and muscles. CUD may be mistaken as Reye syndrome.
A child with CUD may show symptoms between birth and 3 years of age. Vomiting, increased tiredness, behavior changes, low blood sugar, muscle weakness, and heart or liver problems may occur. Fortunately, many symptoms may be avoided with early treatment. Treatment involves L-carnitine supplement to help break down fats. Additionally, your child’s doctor may recommend a specific diet to avoid eating certain fats.
CUD is autosomal recessive, meaning two copies of the changed gene must be present. Early treatment is important. Many babies are screened at birth so that treatment may begin early, however the conditions included in newborn screening vary state by state. For more information, visit Baby’s First Test. Talk with your doctor about the most current treatment options. Support groups also a good source of information. A genetic counselor will help you understand the genetics.