Propionic acidemia is a congenital metabolic disorder where patients experience a buildup of organic acids in the body as a result of being unable to fully metabolize certain proteins and fats. This condition is recessive, with someone needing two copies of the defective gene involved in order to express it, and it tends to be more common in certain populations, including members of the Mennonite community, Saudi Arabians, and Inuit people. This condition is usually diagnosed early in childhood, sometimes within days of a birth.
In patients with propionic acidemia, the metabolism's inability to process some food components results in free-floating organic acids. This can cause toxicity to the organs, and because these acids are not broken down into usable components, the patient may also fail to thrive, since they cannot be accessed for energy and development. In severe cases, within days of birth an infant will become listless, with poor muscle tone and appetite. Other children may develop the disease later in life.
Treatment involves controlling the patient's diet very carefully to restrict foods known to be harmful. This prevents the development of dangerous levels of organic acids. Patients may also benefit from supportive treatment to help them in school and other settings, as propionic acidemia can be associated with developmental delays and learning disabilities in some cases. This is usually the result of slow accrued damage to the brain and other organs.
Two different chromosomes, three and 13, can be involved in propionic acidemia. People may not be aware they are carriers unless there is a known family history of the disease and they have been tested. There is a chance two carriers will have a child without the gene, while in other cases their children may become carriers themselves. If both copies of the bad gene are inherited, the child will develop propionic acidemia. The variance in severity is the result of the different genes involved, as well as minor genetic variations.
People concerned about this metabolic disorder as a result of risk factors for disease or a family history, particularly in the immediate family, can consult a genetic counselor. The counselor can provide testing and an evaluation, along with information about various genetic conditions and their probability. There is no reason carriers should not be able to have children, as long as they understand the risks and are prepared for steps like early testing to diagnose the condition before an infant experiences organ damage.
