Chempath - metabolic disorders and screening Flashcards

1
Q

true positive= 90
false positive = 5
true negative = 80
false negative = 10

What is the specificity?

A

Specificity = the probability that someone without the disease will correctly test -ve

80/85

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2
Q

true positive= 90
false positive = 5
true negative = 80
false negative = 10

What is the sensitivity?

A

Sensitivity = the probability that someone with the disease will correctly test positive

90/100

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3
Q

true positive= 90
false positive = 5
true negative = 80
false negative = 10

What is the positive predictive value

A

PPV = probability that someone with the disease will test +ve

90/95

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4
Q

true positive= 90
false positive = 5
true negative = 80
false negative = 10

What is the negative predictive value

A

NPV = probability that someone without the disease will test -ve

80/90

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5
Q

Phenylketonuria - what is it? what are its manifestations? how is it screened for?

A

Phenylalanine hydroxylase deficiency

Low IQ

measure phenylalanine levels

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6
Q

Congenital hypothyroidism - what is the outcome? how is it screened for?

A

Dysgenesis/agenesis of thyroid gland

Measure TSH levels

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7
Q

What level is measured in blood to screen for CF?

A

Immune reactive trypsin

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8
Q

If immune reactive trypsin level is high, what is done next?

A

DNA mutation detection (4)
If 2 mutations –> CF
If 1 mutation –> repeat with 28
If 0 mutations –> repeat IRT level at 3 weeks of age

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9
Q

Level measured in MCADD screening? how?

A

Acylcarnitine levels by tandem mass spec

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10
Q

metabolic acidosis + high anion gap + high ammonia levels + cheesy sweaty smelling urine

A

Isovolaeric acidaemia

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11
Q

Neonates with organic aciduria:

Findings on neuro exam?
Findings on ABG?
Findings on FBC?

A

Truncal hypotonia + limb hypertonia + myoclonic jerks

Metabolic acidosis + anion gap + high ammonia levels

Pancytopenia

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12
Q

Chronic intermittent form of organic acuduria?

A

Reye syndrome, triggered by aspirin –> Vomiting, lethargy, seizures, confusion, respiratory arrest

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13
Q

Eye effects in galactosaemia

A

Bilateral cataracts

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14
Q

2 major presentations of galactosaemia

A

1) High CONJUG BR

2) SEPSIS

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15
Q

Name the mitochondrial disorder that usually presents at 5-15years of age?

A

MELAS

= mitochondrial encephalopathy, lactic acidosis, stroke-like episodes

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16
Q

Hypoketotic hypoglycaemia + hepatomegaly + cardiomyopathy = ?

A

Mitochondrial fatty acid beta oxidation disorder

17
Q

which lab investigation remains abnormal in remission of Reye syndrome?

A

Blood post carnitine profile

18
Q

Useful lab investigations in a child who’s taken aspirin and is now lethargic + vomiting + confused + seizing

A
  • Plasma glucose + lactate
  • Plasma ammonia
  • Plasma amino acids
  • Urine organic acids
19
Q

Which organs are particularly affected in mitochondrial disorders?

A

Brain, heart, kidney, retina

20
Q

the latest presentation of mitochondrial disorder?

A

Kearns-Sayre syndrome

= ophthalmoplegia, retinopathy, deafness, ataxia

21
Q

CDG type 1a = what type of disorder is this?

A

defect of post-translational glycosylation

22
Q

wtf is a peroxisomal disorder

A

Defect in metabolism of v long chain fatty acids + phospholipid synthesis

23
Q

a neonate has severe muscular hypotonia and dysmorphic features (+/-seizures and hepatic dysfunction). What type of metabolic disorder are you worried about?

A

Peroxisomal disorder

24
Q

What is seen on x-ray of a child with peroxisomal disorder

A

calcified stippling of the patella

25
why does a child with peroxisomal disorder have a huge head?
Large fontanelle, which only closes at 1 year old
26
Which metabolic disorder leads to organomegaly and why?
Lysosomal storage disease --> substrate accumulation in organelles --> organomegally (CT, solid organs, bone, CNS, cartilage) This leads to dysmorphia
27
2 Useful investigations for suspected lysosomal storage disorder (organomegaly of erryting)
1. Urine mucopolysaccharides | 2. Leukocyte enzyme activity
28
1 useful investigation for a child with suspected perixosomal disorder (severe hypotonia + huge head)
Very long chain fatty acid profile
29
Which lab result is super raised after fasting in mitochondrial disorders?
Lactate
30
How to differentiate between Reye syndrome vs mitochondrial fatty acid b-oxidation disorder?
Blood spot carnitine profile = abnormal in Reye's Both present with hypoketotic hypoglycaemia
31
MSUD - inheritance?
Autosomal recessive
32
MSUD is caused by...?
deficiency of branched chain keto-acid dehydrogenase complex
33
Brittle hair Developmental delay Convulsions
Homocystinuria
34
Cause of homocystinuria
cystathionine synthetase deficiency
35
PKU - appearance and smell of child?
Fair child | Musty smell
36
Name an eponymous syndrome which is a glycogen storage disease
Von Gierke's
37
Fabry's disease - what kind of disorder is it? how does it present (3 Fx)?
Lysosomal storage disease LDs + dysmorphia + cherry red spot
38
Cherry red spot
Lysosomal storage disease eg Fabry's
39
V v sweaty feet
Maple syrup urine disease