Inborn errors of metabolization are genetic, congenital disorders that interfere with the way the body metabolizes or uses the substances it receives, usually via food. There are many of these conditions. All together, about .04% of the population suffers from these “errors,” and a defective gene that cannot break down or properly use something the body receives usually characterizes them. This means the body either fails to get a needed substance or a substance builds up in the body to harmful or even fatal levels.
There are two main groups of inborn errors of metabolism. With diseases like PKU, the issue is that the body accumulates too much of a chemical because a genetic defect has robbed it of its ability to break that chemical down. The other group consists of those disorders where the body can’t properly use or metabolize something it does receive, so that the body’s methods for getting energy or other needed resources become impaired.
The most common of the inborn errors of metabolism is the disease phenylketonuria (PKU), which affects about 2.4 in 100,000 people. With this disease, the body lacks the ability to break down phenylalanines, and these cause a harmful build-up which can affect mental and physical health. Concern about this disease is so strong because it begins immediately in infancy and, without diagnosis, may cause irreversible mental retardation quickly.
Many countries routinely test newborns for PKU to prevent this from occurring. If diagnosed early, chances of a healthy life are good. As with many of the inborn errors of metabolism, the goal of treatment is to avoid the substances that create problems. People with PKU must eat a diet absent of phenylalanines to avoid this harmful build-up.
Glycogen storage disease is another type of the inborn errors of metabolism. Those affected lack genes that break down glycogen, which is the stored form of glucose in the body. The result is occasional to frequent inability to use stored glucose as needed for energy. Without intervention, such as use of oral glucose or other medications, some types of this condition are life threatening.
Numerous other types of inborn errors of metabolism occur, and many are exceptionally rare. They’re often inherited in an autosomal recessive pattern, where both parents must pass on a defective gene to offspring. If these illnesses occur in infancy, the presence of a constellation of symptoms, including failure to thrive, poor growth, abnormal development, and irregular blood levels, help diagnose them. Sometimes, a diagnosis does not occur until a child is severely ill, and some of these conditions may cause dangerous crises like sudden seizures or organ failure.
A few of the inborn errors of metabolism aren't manifested until later in life, and some patients wouldn’t receive a diagnosis until mid-adulthood or later. This doesn’t mean these diseases are less serious. In virtually all cases, treatment, predicated on disease type, is necessary.
