What disorders are newborns screened for in the United States?

One of the newest additions to the RUSP is an inherited condition, called SCID , that makes a child’s body unable to fight off even mild infections. The condition, also known as “bubble boy syndrome,” causes parts of the immune system to not work properly. If untreated, infants with SCID are unlikely to live past the age of 2 years. However, when SCID is detected and treated early, children can live longer, healthier lives.

SCID is rare, with between 40 and 100 infants diagnosed each year in the United States. Because SCID is a newcomer to the RUSP, not all states screen for it yet, meaning infants with the condition might be getting sick without being diagnosed.

Infants should be evaluated for SCID and other types of immune system problems if they have:

• A high number of infections
• Infections that do not improve with antibiotic treatment for 2 or more months
• Diarrhea
• Poor weight gain or growth (called “failure to thrive”)
• Fungal infections in the mouth (called “thrush”) that will not go away

An infant with any of these warning signs should be tested for SCID as soon as possible.

PKU (pronounced fee-nill-key-toe-NURR-ee-uh) is a metabolic disorder that is detected by newborn screening. In PKU, the body cannot digest or process one of the building blocks of proteins, an amino acid called phenylalanine (pronounced fen-l-AL-uh-neen), or Phe (pronounced fee). Phe is found naturally in many foods, especially high-protein foods.

PKU was the first condition for which a screening test was developed, and the first condition for which widespread newborn testing was implemented in the 1960s.

If PKU is left untreated, the Phe builds up in the body and brain. By 3 to 6 months of age, infants with untreated PKU begin to show symptoms of intellectual and developmental disability. These disabilities can become severe if Phe remains at high levels.

Fortunately, PKU is treatable. The treatment consists of a diet containing little or no Phe and higher levels of other amino acids. If children with the condition are placed on this diet at birth, they grow normally and usually show no symptoms or health problems. NICHD-sponsored research has shown that people with PKU should stay on the restricted diet as they enter adulthood and, in fact, throughout their lives. This is especially important for women of childbearing age who wish to or who might become pregnant.

Before newborn screening programs could detect PKU in the first few hours after birth, PKU was one of the leading causes of intellectual and developmental disabilities (IDD) in the United States. Today, as a result of newborn screening programs that allow for almost immediate treatment of the condition, PKU has been virtually eliminated as a cause of IDD in this country.

Another metabolic disorder included in newborn screening is galactosemia (pronounced guh-lak-toe-SEE-me-uh), which means being unable to use galactose (pronounced guh-LAK-tohs). Galactose is one of two simple sugars that make up lactose, the sugar in milk. People with galactosemia cannot have any milk or milk products.

If someone with galactosemia consumes milk or milk products (human or animal), the galactose builds up in their blood and causes serious damage to their liver, brain, kidneys, and eyes. Infants with untreated galactosemia can die of a serious blood infection or of liver failure. Those that may survive usually have IDD and other damage to the brain and nervous system. Even milder forms of galactosemia still require treatment to prevent early cataracts, an unsteady gait, and delays in learning, talking, and growth.

The treatment for galactosemia is not to consume any milk or milk products and to avoid other foods that contain this sugar. If this disease is diagnosed very early and the infant is placed on a strict galactose-free diet, she or he is likely to live a relatively normal life, although mild IDD may still develop. If not placed on a galactose-free diet immediately, an infant will develop symptoms in the first few days after birth.

Before it could be detected either before birth or through a newborn screening program, galactosemia was a frequent cause of IDD and early death. Oregon began screening newborns for galactosemia 50 years ago, and all states now screen for this condition. Screening has identified more than 2,500 infants with the condition, many of whom would have died without the screening. ¹