Newborn Screening

Question 1

The majority of newborn screening tests screen for disorders with what MOI?

Answer 1

AR (parents have 25% chance of having another affected child)

looking for undetected disorders that could affect well being and function. Separate those who probably have a disorder from those who do not. Not a diagnostic test, only a screening test. Those who are positive are called “presumed positive”- not definite

Question 2

What are the 6 criteria for choosing a disease for newborn screening? (remember these)

Answer 2

1) serious consequences
2) natural course of disorder should be known
3) incidence of disease should be relatively common (highest cost is the startup of screening, adding additional tests is cheaper)
4) effective and early treatment available
5) efficient screening test available
6) cost/benefit ratio acceptable

Question 3

What are the requirements of the genetic newborn screening tests?

Answer 3

there should be evidence of public benefit. The test should be valid (sensitive- little to no false negatives and specific-few false positives), reliable, inexpensive, ease of performance

Question 4

What are the requirements of the genetic newborn screening programs?

Answer 4

need lab facilities, prompt study of presumed positive cases, methodologies to distinguish truly affected from variants

Question 5

What are some included newborn screening tests in TN?

Answer 5

PKU (first), sickle cell anemia, hypothyroidism, galactosemia, cystic fibrosis, SCID, maple syrup urine disease, homcysteinuria, MCAD

Question 6

All full-term newborns should be tested when?

Answer 6

greater than 24 hrs of age before discharge in order to allow metabolites to equilibrate and norms are set up for greater than 24 hrs of age

all babies get screened for all disorders

Question 7

All premature newborns should be screened when?

Answer 7

before 48 hours of age regardless of diet or illness status

Question 8

Newborn screening is an example of what?

Answer 8

population screening mandated by every state and expect 100% compliance

Question 9

The fatty acids, organic acids, and AAs are in what part of blood?

Answer 9

Serum, as is biotinidase, CF, thyroid stuff (immunoreactvie trypsinogen)

Question 10

What is found in the red blood cells of blood?

Answer 10

hemoglobinopathies, G-6-PD, galactosemia

Question 11

What is found in the white blood cells of blood?

Answer 11

DNA based panels, HIV, toxoplasmosis

Question 12

Who is responsible for obtaining newborn screening?

Answer 12

chief of hospital, attending physician, healthcare provider in non-hospital setting (midwife or NP), parents if the child is born outside of state

Question 13

Why have more disorders been added to newborn screening in recent years?

Answer 13

1) recognition and treatment improved
2) technology advancements
3) support group advocacy

Question 14

What technology is currently used for newborn screening?

Answer 14

tandem mass spectrometry (does orange acids, AAs, and fatty acid oxidations all at once)- uses 3 mm blood spot, which separates them into peaks and bombarded with ions, then to fragments to be integrated and analyzed by a computer

Question 15

T or F. The majority of follow up screens of presumed positives will be normal

Answer 15

T up to 90%

Question 16

What causes lens displacement?

Answer 16

marfans, homocystinuria, etc

Question 17

What are some ‘presumed’ positives not actually affected?

Answer 17

1) immaturity of metabolic systems may cause a false positive
2) cut off are set to have some presumed positives in order not to miss any truly affected by setting the cut off too low (i.e. want 100% SENSITIVITY but okay with not have 100% SPECIFICITY)