Newborn Screening for Genetic Disorders
What is newborn screening and why is it important?Newborn screening refers to a set of tests performed on every newborn baby in the United States. Newborn screening helps to detect diseases that may be serious or life-threatening unless diagnosed early. Many of these diseases are treatable by special precautions, diets, and/or medications, increasing the baby's chance for a healthy life. State laws require that babies be tested within the first few days of life, even if the baby has no symptoms or health problems at birth.
How and why is newborn screening performed?Newborn screening is usually done from a few drops of blood taken from the baby's heel and spotted onto a filter paper. The filter paper is then sent to a laboratory for analysis.
If the blood test comes back positive, the baby’s family and physician will be contacted for further testing. It is important to remember that a positive newborn screen does not mean that the baby has the disorder. However, a positive newborn screen does require appropriate follow up in order to confirm or rule out the disorder.
What diseases are newborns screened for?California screens for approximately 40 different diseases through newborn screening. Listed below are descriptions of some of the more common diseases. A complete list of disorders that are screened for in California can be found at the California Department of Public Health Web site.
- Amino Acid Disorders
Phenylketonuria (PKU): PKU is an inherited disorder in which the body cannot break down a specific component of protein called phenylalanine. When a person with PKU eats foods that contain protein, their levels of phenylalanine rise. High phenylalanine levels for extended periods of time can cause severe intellectual disability, a small head size, seizures, and behavioral problems. Fortunately, PKU can be treated by limiting the amount of protein in the diet. Read a pamphlet for parents with more information about PKU (PDF).
- Organic Acid Disorders
Methylmalonic Acidemia (MMA): MMA is caused by enzyme deficiencies that lead to increased levels of methylmalonic acid and other harmful substances in the blood. Infants with MMA may experience symptoms shortly after birth, such as lethargy and vomiting. If untreated, MMA can lead to seizures, coma, intellectual disability, and death. Treatment can improve outcomes for babies with MMA and includes a low protein diet, certain medications, and precautions when the baby is ill. Read a pamphlet for parents with more information about MMA (PDF).
- Fatty Acid Oxidation Disorders
Medium Chain Acyl CoA Dehydrogenase Deficiency (MCAD Deficiency): MCAD deficiency is caused when an enzyme that is responsible for making energy during times of fasting or illness does not work correctly. Many infants do not have symptoms of MCAD deficiency until they experience a common illness or go for long periods of time without food. If untreated, MCAD deficiency can lead to coma and death. With treatment, including avoidance of fasting and precautions when the baby is ill, these complications can be avoided. Read a pamphlet for parents about MCAD deficiency (PDF).
- Carbohydrate Disorders
Galactosemia: Classic galactosemia is caused when the enzyme that breaks down a sugar called galactose does not work properly. alactose is found in breast milk and cow’s milk as well as many other foods. If not treated, babies with classic galactosemia can develop learning problems, cataracts, liver and kidney problems, and endocrine abnormalities. Treatment can help to prevent some of these problems if started shortly after birth and consists of a diet that is low in lactose and galactose. Read a pamphlet for parents about classic galactosemia (PDF).
- Sickle Cell Disease: Sickle cell disease involves the red blood cells and their ability to carry oxygen. Normal hemoglobin cells are smooth, round, and flexible. Sickle cell hemoglobin cells are stiff and sticky, and form into the shape of a sickle, or the letter "C" when they lose their oxygen. These sickle cells tend to cluster together and can cause painful blockages and spleen damage, leading to increased risk for infections. These infections can be serious for infants and young children. Treatment includes prompt emergency care for fevers and infections, appropriate vaccinations, penicillin, and management of anemia. Read a pamphlet for parents about sickle cell disease (PDF).
- Congenital Hypothyroidism: Congenital hypothyroidism is characterized by an inadequate production of thyroid hormone. Infants with hypothyroidism may have no symptoms for the first several months of life. If untreated, severe intellectual impairment, growth delays, deafness, and other neurological abnormalities can occur. Congenital hypothyroidism is treated with synthetic thyroid hormone. The thyroid is evaluated periodically by blood tests and the infant's growth and development are monitored. Read a pamphlet for parents about congenital hypothyroidism (PDF).
- Cystic Fibrosis: Cystic fibrosis is a disorder that can cause severe lung damage and nutritional deficiencies. Cystic fibrosis affects the cells that produce mucus, sweat, and digestive fluids. Instead of acting as a lubricant, the secretions plug up tubes, ducts and passageways, especially in the pancreas and lungs. There is no cure for cystic fibrosis, but treatments can ease symptoms and reduce complications. In the past, most people with cystic fibrosis died in their teens. Improved screening and treatments now allow many people with cystic fibrosis to live into their 50s or even longer. Read a pamphlet for parents about cystic fibrosis (PDF).
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