Inborn Errors of Metabolism

The birth of a new baby is one of the most thrilling and encompassing experiences in one’s life. The anticipation and arrival brings emotions of joy, fear, and responsibility. New parents eagerly anticipate seeing and holding their new arrival and counting fingers and toes to confirm that their baby is normal and healthy. In most cases a healthy looking baby is indeed healthy, but there are some exceptions to this statement.

Certain genetically determined conditions do not affect the physical features of the baby but have an adverse effect on the biochemical pathways in the body. These disorders may result in underdeveloped growth, mental retardation, seizures and even death if not detected and treated early. What is encouraging, however, is that these disorders referred to as inborn errors of metabolism can be detected in the newborn period using a small blood sample from the baby. Early treatment may not “cure” the disorder but treatment can minimize or prevent the serious effects and allow for normal development and growth.

Inborn errors of metabolism are inherited disorders. Most of these disorders are recessive conditions, meaning that a baby would have to receive one faulty gene from each parent in order to have the condition.

Newborn screening programs to detect inborn errors of metabolism exist in every state but may differ in the number and types of tests provided. Currently, the South Carolina Newborn Screening Program tests for six conditions. These conditions include phenylketonuria (PKU), congenital hypothyroidism, galactosemia, congenital adrenal hyperplasia (CAH), medium chain acyl co-A dehydrogenase deficiency (MCADD), and hemoglobinopathies. The testing is carried out on a spot of blood collected from the newborn’s heel. DHEC is responsible for the newborn testing in South Carolina and currently is considering expansion of the program to include testing for additional conditions.

If caught early, a baby and family can avoid unfortunate outcomes through dietary controls and medical interventions.