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LMP301 > LMP301 Lecture 19: Newborn Screening > Flashcards

LMP301 Lecture 19: Newborn Screening Flashcards

(53 cards)

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1
Q

when does newborn screening happen?

A

first 1-2 days of life

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2
Q

what is used for newborn screening?

A

blood from heel of infant

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3
Q

newborn screening procedure

A
  1. collect blood from heel of infant
  2. dot on filter paper
  3. send to newborn screening program along with baby/family info (usually in country capital)
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4
Q

PKU

A

phenylketouria

= phenylketones in the urine

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5
Q

can PKU be treated?

A

yes

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6
Q

symptoms of PKU

A
  • mental retardation
  • blond hair (even if not in family)
  • low IQ (35)
  • smell (phenylpyruvate, phenylketones in urine)
  • decreased pigmentation
  • seizures
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7
Q

what is the toxic material in PKU?

A

Phe

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8
Q

Phe causes acute toxicity if greater than…

A

1300 uM

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9
Q

what is the consequence of excess Phe?

A
  • build up in blood
  • acute toxicity
  • affect brain development
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10
Q

PKU is a ___ disorder

A

Phe metabolism

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11
Q

PKU is caused by…

A

deficiency of phenylalanine hydroxylase (PAH)

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12
Q

pheylalaline hydroxylase

A

Phe -> Tyr

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13
Q

“-emia”

A

in the blood

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14
Q

what happens when Phe can’t be converted to Tyr?

A

converted to phenylketones instead

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15
Q

what type of disease is PKU (genetics)

A

autosomal recessive

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16
Q

incidence of PKU

A

1 in 10 000

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17
Q

incidence of PKU carrier

A

1 in 50

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18
Q

why is decreased pigmentation in those with PKU?

A

lack of Tyr, which is metabolized to produce melanin

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19
Q

why is there decreased mental capabilities in those with PKU?

A
  • Phe is toxic to brain development

- missing many NT due to lack of Tyr

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20
Q

what can be used to examine amount of Phe in the blood?

A

ultra-performance liquid chromotography

  • separate all AA in blood and see levels of each
  • see if Phe exceeds normal level
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21
Q

what type of testing is used to determine PKU?

A

chromotography

NO genetic testing

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22
Q

is genetic testing used to diagnose PKU?

23
Q

treatment of PKU

Study These Flashcards
A

dietary: limit Phe in diet

this will prevent mental retardation

24
Q

when should treatment for PKU begin?

Study These Flashcards
A

during first 10-12 days of life, and is lifelong

25
which foods should PKU patients avoid?
- protein (meats, fish, eggs, poultry) | - bread, potatoes, vegetables (restricted based on individual tolerance)
26
which group really needs to watch their Phe intake if they have PKU?
pregnant women: may affect baby brain development
27
what is it called when a baby is mentally retarded due to mom not taking care of diet during pregnancy?
Maternal PKU - mental abilities affected - baby does not necessarily have PKU
28
beside defects in PAH, what may also cause PKU?
biopterin defects (problems with co-factors that help PAH)
29
mutations/defect in ___ will result in cofactors that cannot support action of PAH
- GTPCH - PTPS - DHPR - PCD
30
PTPCH
GTP cyclohydrolase
31
PTPS
pyruvoyltetrahydropteridin synthase
32
DHPR
dihydropteridine reductase
33
PCD
pterin 4 alpha-carbinolamine dehydratase
34
symptoms of individuals with PKU due to biopterin defects
- mental problems - abnormal levels of serotonin & dopamine - epileptic crisis - seizures - lower levels of Phe accumulation (not primary PKU), but equally bad symptoms
35
Biopterin defects account for...
5% of all PKU cases
36
how to treat those with PKU due to biopterin defects?
- give biopterin | - will not respond to Phe-restricted diet
37
What is the most common disorder tested for in newborn screening?
PKU
38
difference between newborn screening (NBS) and testing
NBS is performed on every newborn, but testing is only for those who are suspected of having a disease (results from screening, family history, symptoms)
39
define: NBS
testing of ALL newborn children in order to detect diseases for which early intervention is available, necessary, and alters course of the disease
40
there is no point testing for which types of diseases?
diseases with no treatment options
41
about how many diseases are screened?
30
42
criteria for the type of disease screened
1. high frequency disease 2. know disease history (what happens if disease is untreated) 3. disease causes significant morbidity/mortality 4. treatable, and treatment improves outcome 5. testing is safe, simple, sensitive, fast 6. confirmatory testing is available 7. cost-effective
43
what technique is used for newborn screening?
tandem mass spectrometry - inject plasma into mass spec - ionized - AA separated based on weight (look at combined weight of elements that make up that AA)
44
MW of Phe
165.08
45
benefits of using mass spec as testing method
- fast (results out in 24-48h) - sensitive, specific - automated - many samples examined at same time - many disorders examined at same time
46
are NBS tests diagnostic?
no
47
NBS process
1. obtain sample 2. send to neonatal screening program 3. test 4. results 5. contact family (if needed) 6. direct to physician 7. confirmatory testing 8. follow-up 9. counselling
48
what has to be considered if NBS screen tests positive?
- test family members (because all diseases screened are of genetic origin) - counselling - management of disease - risk in future pregnancies - alternative methods of future reproduction
49
congenital hypothyrodism causes...
mental retardation
50
MCAD
- high frequency disorder - sudden infant death due to inability to break down FA - hypoglycemic - can't break down FA to ketones, so no energy to brain when fasting (e.g. sleep)
51
treatment for MCAD
wake up kid every few hours to eat
52
which type of screening is performed for cystic fibrosis?
both biochemical & genetic screening - 2 types of screening - only for this disorder
53
TMS
tandem mass spectrometry

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