Which Tests Are Offered?
Traditionally, state decisions about what to screen for have been based on weighing the costs against the benefits. "Cost" considerations include:
- the risk of false positive results (and the worry they cause)
- the availability of treatments known to help the condition
- financial costs
So what can you do? Your best strategy is to stay informed. Discuss this issue with both your obstetrician or health care provider and your future baby's doctor before you give birth. Know what tests are routinely done in your state and in the hospital where you'll deliver (some hospitals go beyond what's required by state law).
If your state isn't offering screening for the expanded panel of disorders, you may want to ask your doctors about supplemental screening, though you'll probably have to pay for additional tests yourself.
If you're concerned about whether your infant was screened for certain conditions, ask your child's doctor for information about which tests were done and whether further tests are recommended.
Newborn screening varies by state and is subject to change, especially given advancements in technology. However, the disorders listed here are the ones typically included in newborn screening programs.
When this disorder is detected early, feeding an infant a special formula low in phenylalanine can prevent mental retardation. A low-phenylalanine diet will need to be followed throughout childhood and adolescence and perhaps into adult life. This diet cuts out all high-protein foods, so people with PKU often need to take a special artificial formula as a nutritional substitute. Incidence: 1 in 10,000 to 25,000.
This is the disorder most commonly identified by routine screening. Affected babies don't have enough thyroid hormone and so develop retarded growth and brain development. (The thyroid, a gland at the front of the neck, releases chemical substances that control metabolism and growth.)
If the disorder is detected early, a baby can be treated with oral doses of thyroid hormone to permit normal development. Incidence: 1 in 4,000.
Babies with galactosemia lack the enzyme that converts galactose (one of two sugars found in lactose) into glucose, a sugar the body is able to use. As a result, milk (including breast milk) and other dairy products must be eliminated from the diet. Otherwise, galactose can build up in the system and damage the body's cells and organs, leading to blindness, severe mental retardation, growth deficiency, and even death.
Incidence: 1 in 60,000 to 80,000. Several less severe forms of galactosemia that may be detected by newborn screening may not require any intervention.
Sickle Cell Disease
Sickle cell disease is an inherited blood disease in which red blood cells mutate into abnormal "sickle" shapes and can cause episodes of pain, damage to vital organs such as the lungs and kidneys, and even death. Young children with sickle cell disease are especially prone to certain dangerous bacterial infections, such as pneumonia (inflammation of the lungs) and meningitis (inflammation of the brain and spinal cord).
Studies suggest that newborn screening can alert doctors to begin antibiotic treatment before infections occur and to monitor symptoms of possible worsening more closely. The screening test can also detect other disorders affecting hemoglobin (the oxygen-carrying substance in the blood).
Incidence: about 1 in every 500 African-American births and 1 in every 1,000 to 1,400 Hispanic-American births; also occurs with some frequency among people of Mediterranean, Middle Eastern, and South Asian descent.
Babies with this condition don't have enough biotinidase, an enzyme that recycles biotin (a B vitamin) in the body. The deficiency may cause seizures, poor muscle control, immune system impairment, hearing loss, mental retardation, coma, and even death. If the deficiency is detected in time, however, problems can be prevented by giving the baby extra biotin. Incidence: 1 in 72,000 to 126,000.
Congenital Adrenal Hyperplasia
This is actually a group of disorders involving a deficiency of certain hormones produced by the adrenal gland. It can affect the development of the genitals and may cause death due to loss of salt from the kidneys. Lifelong treatment through supplementation of the missing hormones manages the condition. Incidence: 1 in 12,000.
Maple Syrup Urine Disease (MSUD)
Babies with MSUD are missing an enzyme needed to process three amino acids that are essential for the body's normal growth. When not processed properly, these can build up in the body, causing urine to smell like maple syrup or sweet, burnt sugar. These babies usually have little appetite and are extremely irritable.
If not detected and treated early, MSUD can cause mental retardation, physical disability, and even death. A carefully controlled diet that cuts out certain high-protein foods containing those amino acids can prevent this. Like people with PKU, those with MSUD are often given a formula that supplies the necessary nutrients missed in the special diet they must follow. Incidence: 1 in 250,000.
Babies with this amino acid metabolism disorder have trouble processing the amino acid tyrosine. If it accumulates in the body, it can cause mild retardation, language skill difficulties, liver problems, and even death from liver failure. Treatment requires a special diet and sometimes a liver transplant. Early diagnosis and treatment seem to offset long-term problems, although more information is needed. Incidence: not yet determined. Some babies have a mild self-limited form of tyrosinemia.
Cystic fibrosis (CF) is a genetic disorder that particularly affects the lungs and digestive system and makes kids who have it more vulnerable to repeated lung infections. There is no known cure — treatment involves trying to prevent serious lung infections (sometimes with antibiotics) and providing adequate nutrition. Early detection may help doctors reduce the problems associated with CF, but the real impact of newborn screening has yet to be determined. Incidence: 1 in 2,000 Caucasian babies; less common in African-Americans, Hispanics, and Asians.
MCAD (medium chain acyl CoA dehydrogenase) deficiency is a fatty acid metabolism disorder. Kids who have it are prone to repeated episodes of low blood sugar (hypoglycemia), which can cause seizures and interfere with normal growth and development. Treatment involves making sure kids don't fast (skip meals) and supplies extra nutrition (usually by intravenous nutrients) when they're ill. Early detection and treatment can help affected children live normal lives.
Toxoplasmosis is a parasitic infection that can be transmitted through the mother's placenta to an unborn child. The disease-causing organism can invade the brain, eye, and muscles, possibly resulting in blindness and mental retardation. The benefit of early detection and treatment is uncertain. Incidence: 1 in 1,000. But only one or two states screen for toxoplasmosis.
Most but not all states require newborns' hearing to be screened before they're discharged from the hospital. If your baby isn't examined then, be sure that he or she does get screened within the first 3 weeks of life.
Kids develop critical speaking and language skills in their first few years. A hearing loss that's caught early can be treated to help prevent interference with that development.
Should I Request Additional Tests?
If you answer "yes" to any of these questions, talk to your doctor and perhaps a genetic counselor about additional tests:
- Do you have a family history of an inherited disorder?
- Have you previously given birth to a child who's affected by a disorder?
- Did an infant in your family die because of a suspected metabolic disorder?
- Do you have another reason to believe that your child may be at risk for a certain condition?