2. WHAT IS NEWBORN SCREENING ?
Newborn screening is a public health program
designed to screen infants shortly after birth
for a list of conditions that are treatable but
not clinically evident in newborn period.
3. WHAT FOR NEWBORN SCREENING ?
• “The goal of newborn screening is early
detection of children at increased risk for
selected metabolic or genetic diseases so that
medical treatment can be promptly initiated
to avert metabolic crises and prevent
irreversible neurological and developmental
sequelae.”
4. HISTORY OF NEW BORN SCREENING
• 1930’s George Jervis at NY identified 50 clients
with metal retardation attributed to PKU
• 1963 Robert Guthrie, microbiologist-
pediatrician at State University of New York
devised simple inexpensive which allowed
screening for PKU
• 1965 New York State law for newborn
screening, Public Health Law 2500
5. • 1970 -1980s: congenital
hypothyroidism, congenital adrenal
hyperplasia, galactosemia
• 1990s:DNA tests used as second tier – Sickle
Cell Disease screening, Cystic Fibrosis
screening
• 2000s : Tandem Mass Spectrometer (MS/MS)
Many diseases, one test
6. CARDINAL PRINCIPLES OF SCREENING
• The disorder has a relatively high incidence so that the
cost per diagnosed individual is reasonable
• An effective and not overly expensive treatment is
available.
• A relatively inexpensive screening test that is suitable
for high volume testing (preferably automatable)
• The screening test has a very high sensitivity (very low
false negatives) and high specificity (low false positives
which require expensive follow-up)
7. CRITERIA FOR NEWBORN SCREENING
• Disorder produces irreversible damage before
onset of symptoms
• Treatment is effective if begun early
• Natural history of disorder is known
8. SCREENING PROCEDURE
• SPECIMEN COLLECTION
Blood specimen is obtained from heel of infant
It should be obtained from medial or lateral side
of the heel
9. TIMING OF COLLECTION
• Normal Term Newborn: Before nursery
discharge or 3rd day of life whichever is earlier.
• Preterm or LBW: 2 wks of age or at discharge
whichever is earlier.
• Newborn who is to receive blood transfusion,
One specimen collected before transfusion &
second specimen 2 days after transfusion.
10. SCREENING TESTS
• BACTERIAL ASSAYS:
Punching of small disc from Guthrie specimen
Disc are place in agar or silica gel & contain
bacteria growth media & other necessary factors
Each bacterial plate are specified for response to a
particular metabolite.
The amount of growth around the disc is directly
proportional to the concentration of metabolite in
blood.
They are used to screen for amino acid disorders.
13. Tandem Mass Spectrometry (MS/MS) High
Impact and High Throughput
• One disease, one test is not cost-effective
• Many diseases, one test is cost-effective
• MS/MS allows for rapid, simultaneous analysis
and detection of many disorders of amino
acid, organic acid, and fatty acid metabolism
• Sample set up determines which masses and
therefore which compounds are detected
• 2 minute analysis time
• Automated data processing for results
14. MS/MS Methodology – continued
Compounds analyzed are amino acids and
acylcarnitines
–Amino acids – to identify
PKU, MSUD, homocystinuria
–Acylcarnitine – carnitine (vehicle) + fatty
acid for identification of organic acidurias
and fatty acid oxidation disorders
15. SECONDARY TEST
• An abnormal finding on newborn screening
test is not diagnostic of a disorder.
• Additional tests should be performed to
substantiate the original finding.
• Also the original specimen is retested for the
analyte that is abnormal.
16. • In screening for congenital hypothyroidism,
Low T4
TSH Immunoassay
Low TSH Normal TSH
Congenital Transient low T4
Hypothyroidism
18. PHENYLKETONURIA
• INCIDENCE: 1 IN 12000 live births
• Untreated: Mental retardation & neurological
abnormalities
• Screening is done by MS/MS
• Screening test is positive if phenylalanine level
is > 6mg/dl
• Liver disease, Galactosemia & Tyrosinemia
type 1 can also produce phenylalanine levels.
19. CONGENITAL HYPOTHYROIDISM
• INCIDENCE: 1 in 3000 to 5000 newborn
• UNTREATED: Growth retardation & delayed
cognitive development
• Two Screening approaches are used
Primary screening for low T4 with secondary
screening for high TSH
Primary screening for high TSH
20. • FALSE POSITIVE
Low T4: Premature infants, Thyroxin binding
globulin deficiency
High TSH: Perinatal stress
• FALSE NEGATIVE
Normal T4: In first 24hrs of life.
Normal TSH: In premature infants with CH it may
take 2 or more wks for TSH elevation to develop
21. GALACTOSEMIA
• INCIDENCE: 1 in 62000
• MANIFESTATIONS: Failure to
thrive, vomiting, Liver disease & death from
sepsis due to E.Coli
• 2 Screening Test
SPECIFIC ENZYME ASSAY
Measures activity of Galactose 1 Phosphate Uridyl
Transferrase
Identifies only galactosemia
22. METABOLITE ASSAY
Measures total Galactose(galactose & galactose 1
phosphate)
Identifies other galactose metabolic disorders like
Galactokinase & Epimerase deficiency
POSITIVE SCREENING TEST
RAPID CONFIRMATORY TEST
TESTING OF URINE FOR REDUCING SUBSTANCES
23. URINE CONTAINS REDUCING SUBSTANCES
DISCONTINUATION OF BREAST OR FORMULA FEEDS
SUBSTITUTION WITH NON LACTOSE FORMULA Eg, SOY
ENZYME ASSAY FOR RBC GALT ACTIVITY
24. HOMOCYSTINURIA
• INCIDENCE: 1 IN 344,000 births
• UNTREATED: Ectopia lentis, Osteoporosis
Thromboembolism, Mental Retardation
• SCREENING MARKER: Plasma Methionine
levels.
• MS/MS is used for screening
25. • Isolated Hypermethioninemia may occur in
MAT Deficiency,
Tyrosinemia type 1
Liver disease
• HOMOCYSTINURIA
Homocysteine is detectable in plasma & urine
Plasma total Homocysteine & Methionine
Plasma cysteine is reduced
27. MAPLE SYRUP URINE DISEASE
• INCIDENCE: 1 IN 185,000 births
• FULMINANT DISEASE: Severe
Ketoacidosis, Vomiting & lethargy & may
progress to coma & death
• SCREENING MARKER: 4 fold elevation of
plama leucine in NB
28. • Confirmatory plasma & urine specimens
obtained
• Plasma shows marked increase in leucine,
isoleucine & valine (branched chain amino
acids)
• Urine is strongly positive for ketones
• Maple syrup odor appears earliest in cerumen
& later in urine. Can be detected by cotton
tipped swab inserted into infant’s ear.
29. • CONGENITAL ADRENAL HYPERPLASIA
Screening Marker: Increased levels of 17OHP
• SICKLE CELL DISEASE
Screening is by means of Hemoglobin
electrophoresis.
It also identifies sickle cell trait & other abnormal
hemoglobins.
30. OTHER DISORDERS DETECTED BY
NEWBORN SCREENING
• BIOTINIDASE DEFICIENCY
• OTHER AMINO ACID DISORDERS: Eg
Citrullinemia
• LONG CHAIN & MEDIUM CHAIN ACYL CoA
DEHYDROGENASE DEFICIENCY
• CYSTIC FIBROSIS
• NEUROBLASTOMA
