All states in the U.S. offer newborn screening, which involves testing a small sample of a newborn's blood obtained for various genetic conditions. The number of conditions tested for varies from state to state, but new developments in testing methodologies have increased the number and type of tests being offered. By detecting problems in the first few days of life, newborn screening can save lives and improve the health of babies in the short term and the long run.
Conditions Needing Immediate Treatment
Newborn screening can save lives by detecting metabolic diseases that require treatment in the first days of life. These diseases are rare but can lead to devastating consequences if not detected and treated right away. Most of these diseases are inherited in an autosomal recessive manner, which means that each of the baby's parents passed on a mutation in the same gene to the baby.
One example is phenylketonuria, or PKU, which affects between 1 in 2600 and 1 in 100,000 individuals (depending on ethnic background). Classic PKU is caused by deficiency of an enzyme called phenylalanine hydroxylase. Without this ezyme, phenylalanine concentrations in the body rise, causing profound and irreversible mental retardation. PKU is treated by limiting protein intake and feeding babies a phenylalanine-free special formula. If this special diet is not started right after birth and continued at least into adolescence, affected children will develop seizures, mental retardation and behavior problems. Because of newborn screening, individuals with PKU need not face the devastating consequences of the disease that were inevitable before the disease could be diagnosed so early.
Conditions Needing Later Treatment
Newborn screening also detects hemoglobinopathies, which are inherited changes of hemoglobin, the substance that carries oxygen in the blood. Several different forms of hemoglobinopathies exist, each inherited as an autosomal recessive condition. In most cases, hemoglobinopathies do not need to be treated right away because symptoms are not apparent at birth. Over time, however, health problems, such as anemia and infections, can develop. Knowing about the diagnosis shortly after birth enables precautions and treatments to be put into place as they become needed.
One of the most common hemoglobinopathies is sickle cell disease. Approximately 7 percent of the world's population is a carrier of sickle cell anemia. When an infant is diagnosed with sickle cell anemia by newborn screening, parents can arm themselves with information regarding steps they can take to prevent, detect and quickly treat the painful "crises" (when sickle-shaped blood cells become stuck in blood vessels) and other complications of the disease.
Newborn screening can also detect babies that are carriers of, but not affected with, hemoglobinopathies. For carriers of these conditions, no treatment is generally necessary, but precautions can be taken to prevent symptoms from occurring. For example, if carriers of sickle cell anemia are exposed to low-oxygen conditions, such as extreme physical exertion or high altitude, their blood can sickle. Maintaining proper hydration and avoiding very high altitudes can prevent the sickling.
Hearing Loss
In addition to genetic conditions, newborn screening now also includes tests for hearing loss. This is performed by playing sounds into a baby's ears and measuring the baby's response. Approximately 1 to 2 percent of all newborns have significant hearing loss.
Children identified with hearing loss under six months of age stand a better chance than those identified at later ages of developing speech and language skills at the same level as their peers by the time they enter kindergarten. Some parents choose to treat hearing loss, when possible, with devices such as cochlear implants. When cochlear implants are performed early in life, the baby is exposed to sounds during the critical time of development of speech and language skills.
