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Main article: Prenatal diagnosis

Newborn screening is the process of testing newborn babies for treatable genetic, endocrinologic, metabolic and hematologic diseases.[1][2] Newborn screening has been adopted by most countries around the world, though the lists of screened diseases vary widely.

Disease qualificationEdit

Common considerations in determining whether to screen for disorders:

  1. A disease that can be missed clinically at birth
  2. A high enough frequency in the population
  3. A delay in diagnosis will induce irreversible damages to the baby
  4. A simple and reasonably reliable test exists
  5. A treatment or intervention that makes a difference if the disease is detected early

Newborn Screening Program in the PhilippinesEdit

The following tests are mandated in the R.A. 9288 or Newborn Screening program of 2004.Newborn screening is available in practicing health institutions (hospitals, lying-ins, Rural Health Units and Health Centers) with cooperation with DOH. If babies are delivered at home, babies may be brought to the nearest institution offering newborn screening. A negative screen mean that the result of the test is normal and the baby is not suffering from any of the disorders being screened. In case of a positive screen, the NBS nurse coordinator will immediately inform the coordinator of the institution where the sample was collected for recall of patients for confirmatory testing. Babies with positive results should be referred at once to the nearest hospital or specialist for confirmatory test and further management. Should there be no specialist in the area, the NBS secretariat office will assist its attending physician. Disorders Screened:

File:Phenylketonuria testing.jpg
  • CH (Congenital hypothyroidism) - is a condition of thyroid hormone deficiency present at birth. Approximately 1 in 4000 newborn infants has a severe deficiency of thyroid function, while even more have mild or partial degrees. If untreated for several months after birth, severe congenital hypothyroidism can lead to growth failure and permanent mental retardation. Treatment consists of a daily dose of thyroid hormone (thyroxine) by mouth. Because the treatment is simple, effective, and inexpensive, nearly all of the developed world practices newborn screening to detect and treat congenital hypothyroidism in the first weeks of life.
  • CAH (Congenital adrenal hyperplasia) - refers to any of several autosomal recessive diseases resulting from mutations of genes for enzymes mediating the biochemical steps of production of cortisol from cholesterol by the adrenal glands (steroidogenesis). Most of these conditions involve excessive or deficient production of sex steroids and can alter development of primary or secondary sex characteristics in some affected infants, children, or adults. Approximately 95% of cases of CAH are due to 21-hydroxylase deficiency.
  • GAL (Galactosemia) - is a rare genetic metabolic disorder which affects an individual's ability to properly metabolize the sugar galactose. Lactose in food (such as dairy products) is broken down by the body into glucose and galactose. In individuals with galactosemia, the enzymes needed for further metabolism of galactose are severely diminished or missing entirely, leading to toxic levels of galactose to build up in the blood, resulting in hepatomegaly (an enlarged liver), cirrhosis, renal failure, cataracts, and brain damage. Without treatment, mortality in infants with galactosemia is about 75%.
  • PKU (Phenylketonuria) - is an autosomal recessive genetic disorder characterized by a deficiency in the enzyme phenylalanine hydroxylase (PAH). This enzyme is necessary to metabolize the amino acid phenylalanine to the amino acid tyrosine. When PAH is deficient, phenylalanine accumulates and is converted into phenylpyruvate (also known as phenylketone), which is detected in the urine. PAH is found on chromosome number 12.Left untreated, this condition can cause problems with brain development, leading to progressive mental retardation and seizures. However, PKU is one of the few genetic diseases that can be controlled by diet. A diet low in phenylalanine and high in tyrosine can be a very effective treatment. There is no cure. Damage done is irreversible so early detection is crucial.
  • G6PD Deficiency - is an X-linked recessive hereditary disease characterized by abnormally low levels of the glucose-6-phosphate dehydrogenase enzyme (abbreviated G6PD or G6PDH). It is a metabolic enzyme involved in the pentose phosphate pathway, especially important in red blood cell metabolism.
  • Newborn screening results are available within three weeks after the NBS Lab receives and tests the samples sent by the institutions. Results are released by NBS Lab to the institutions and are released to your attending birth attendants or physicians.Parents may seek the results from the institutions where samples are collected. Christian Nieto,EACSN

Newborn screening in the United StatesEdit

The following tests are mandated (required to be performed on every newborn born in the state) in most of the United States. According to the U.S. Centers for Disease Control, approximately 3,000 babies with severe disorders are identified in the United States each year using newborn screening programs at current testing rates. States vary, and not all tests are required in every state, and a few states mandate more than this. The first test to be universally mandated across the U.S. was the Guthrie test for phenylketonuria (PKU), and in many areas and hospitals, the newborn blood test is often erroneously referred to as a "PKU test", even though all states now universally test for congenital hypothyroidism, galactosemia, and increasing numbers of other diseases as well.

For a recent state-by-state list, see U.S. National Newborn Screening and Genetics Resource Center. According to this resource, the only tests mandated in every state are the following:

  • CH - Congenital hypothyroidism
  • H-HPE - Benign hyperphenylalaninemia
  • PKU -- Phenylketonuria/hyperphenylalaninemia
  • HEAR - Hearing
  • GALT - Transferase deficient galactosemia

Usual procedures and responses to positive resultsEdit

File:Phenylketonuria testing.jpg

In nearly all of the United States, the newborn screening program is a division of the state health department. State law mandates collecting a sample by pricking the heel of a newborn baby to get enough blood (typically, two to three drops) to fill a few circles on filter paper labeled with names of infant, parent, hospital, and primary physician. It is usually specified that the sample be obtained on the second or third day of life, after protein-containing feedings (i.e., breast milk or formula) have started, and the postnatal TSH surge subsided. Every hospital in the state as well as independent midwives supervising home deliveries are required to collect the papers and mail each batch each day to the central laboratory.

The state health department agency in charge of screening will either run a laboratory or contract with a laboratory to run the mandated screening tests on the filter paper samples. The goal is to report the results within a short period of time. If screens are normal, a paper report is sent to the submitting hospital and parents rarely hear about it.

If an abnormality occurs, employees of the agency, usually nurses, begin to try to reach the physician, hospital, and/or nursery by telephone. They are persistent until they can arrange an evaluation of the infant by an appropriate specialist physician (depending on the disease). The specialist will attempt to confirm the diagnosis by repeating the tests by a different method or laboratory, or by performing other corroboratory or disproving tests. Depending on the likelihood of the diagnosis and the risk of delay, the specialist will initiate treatment and provide information to the family. Performance of the program is reviewed regularly and strenuous efforts are made to maintain a system that catches every infant with these diagnoses. Guidelines for newborn screening and follow up have been published by the American Academy of Pediatrics.[3]

Recommended target conditions and disordersEdit

The following list includes most of the disorders detected by the expanded or supplemental newborn screening by mass spectrometry. This expanded screening is not yet universally mandated by most states, but may be privated purchased by parents or hospitals at a cost of approximately US$80. Perhaps one in 5,000 infants will be positive for one of the metabolic tests below (excluding the congenital infections).

Core panelEdit

The following conditions and disorders were recommended as "core panel" by the 2005 report of the American College of Medical Genetics (ACMG).[4] The incidences reported below are from their report, pages 143-307, though the rates may vary in different populations. (WARNING: The file is a very large PDF.)

Blood cell disorders

Inborn errors of amino acid metabolism

Inborn errors of organic acid metabolism

Inborn errors of fatty acid metabolism

Miscellaneous multisystem diseases

Newborn screening by other methods than blood testing

Secondary targetsEdit

The following disorders are additional conditions that may be detected by screening. Many[4] are listed as "secondary targets" by the 2005 report ACMG. Some states are now screening for more than 50 congenital conditions. Many of these are rare and unfamiliar to pediatricians and other primary health care professionals.[4]

Blood cell disorders

Inborn errors of amino acid metabolism


Inborn errors of organic acid metabolism

Inborn errors of fatty acid metabolism

Congenital infections

Miscellaneous multisystem diseases

Expanded screening and controversiesEdit

With the development of tandem mass spectrometry in the early 1990s, the number of detectable diseases quickly grew, especially in the categories of fatty acid oxidation disorders and organic acidoses. Screening tests for the disorders listed below (and an increasing number of others) are now available, though not universally mandated. There is considerable variability from state to state, and sometimes from hospital to hospital within a state, on disease that are screened. To make matters more confusing, some hospitals routinely obtain supplemental screening (most of the tests below) on all infants even if not mandated by the state or requested by parents. In recent years in the United States, expanded newborn screening with tandem mass spectrometry has become a profitable commercial venture.

Newborn screening tests have become a subject of political controversy in the last decade. Two California babies, Zachary Wyvill and Zachary Black, were both born with Glutaric acidemia type I. Wyvill's birth hospital only tested for the four diseases mandated by state law, while Black was born at a hospital that was participating in an expanded testing pilot program. Black's disease was treated with diet and vitamins; Wyvill's disease went undetected for over six months, and during that time the damage from the enzyme deficiency became irreversible. Birth-defects lobbyists pushing for broader and more universal standards for newborn testing cite this as an example of how much of an impact testing can have.

Instituting MS/MS screening often requires a sizable up front expenditure. When states choose to run their own programs the initial costs for equipment, training and new staff can be significant. To avoid at least a portion of the up front costs, some states such as Mississippi have chosen to contract with private labs for expanded screening. Others have chosen to form Regional Partnerships sharing both costs and resources. But for many states, screening is an integrated part of the department of health which can not or will not be easily replaced. Thus the initial expenditures can be difficult for states with tight budgets to justify. Screening fees have also increased in recent years as healthcare costs rise and more states add MS/MS screening to their programs. (See Report of Summation of Fees Charged for Newborn Screening, 2001–2005) Dollars spent for these programs may reduce resources available to other potentially lifesaving programs. It has been recommended that one disorder, Short Chain Acyl-coenzyme A Dehydrogenase Deficiency, or SCAD, be eliminated from screening programs, due to a "spurious association between SCAD and symptoms. [6] However, recent studies suggest that expanded screening is cost effective (see ACMG report page 94-95 and articles published in Pediatrics [7]'[8]. Advocates are quick to point out studies such as these when trying to convince state legislatures to mandate expanded screening.

Expanded newborn screening is also opposed by among some health care providers who are concerned that effective follow-up and treatment may not be available, that false positive screening tests may cause harm, and issues of informed consent[9].

Newborn screening programs worldwideEdit

Newborn screening has also been adopted by most countries in Europe and around the world, though the lists of screened diseases vary widely.

HistoryEdit

Robert Guthrie is given much of the credit for pioneering the earliest screening for phenylketonuria in the late 1960s using blood samples on filter paper obtained by pricking a newborn baby's heel on the second day of life to get a few drops of blood. [10] Congenital hypothyroidism was the second disease widely added in the 1970s.[11] The development of tandem mass spectrometry screening by Edwin Naylor and others in the early 1990s led to a large expansion of potentially detectable congenital metabolic diseases that affect blood levels of organic acids.[12] Additional tests have been added to many screening programs over the last two decades.

See alsoEdit

ReferencesEdit

  1. Tarini BA (2007). The current revolution in newborn screening: new technology, old controversies. Archives of pediatrics & adolescent medicine 161 (8): 767–72.
  2. Kayton A (2007). Newborn screening: a literature review. Neonatal network : NN 26 (2): 85–95.
  3. Newborn Screening Expands: Recommendations for Pediatricians and Medical Homes-Implications for the System. Pediatrics121:1 192-217 January 2008[1]
  4. 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 4.25 4.26 Newborn Screening Expands: Recommendations for Pediatricians and Medical Homes Implications for the System Newborn Screening Authoring Committee. Pediatrics 2008;121;192-217 DOI:10.1542/peds.2007-3021.
  5. labtestsonline.org > Screening Tests for Newborns American Association for Clinical Chemistry. This page was last reviewed on March 16, 2008. | This page was last modified on December 1, 2009.
  6. Newborn Screening for Metabolic Disorders. Journal of the American Medical Association 2006 PMID 16926360
  7. Expanded Newborn Screening for Inborn Errors of Metabolism by Electrospray Ionization-Tandem Mass Spectrometry: Results, Outcome and Implication PMID 12777559 [2]<
  8. Cost-Benefit Analysis of Universal Tandem Mass Spectrometry for Newborn Screening. Pediateics 2002 PMID 12359795 [3]
  9. Financial, Ethical, Legal, and Social Issues
  10. Clague A, Thomas A (2002). Neonatal biochemical screening for disease. Clin. Chim. Acta 315 (1-2): 99–110.
  11. Klein AH, Agustin AV, Foley TP (1974). Successful laboratory screening for congenital hypothyroidism. Lancet 2 (7872): 77–9.
  12. Chace DH, Kalas TA, Naylor EW (2003). Use of tandem mass spectrometry for multianalyte screening of dried blood specimens from newborns. Clin. Chem. 49 (11): 1797–817.

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