Metabolic Disorders Flashcards

1
Q

Which disorders does the Guthrie blood spot test screen for?

A

Phenylketonuria, congenital hypothyroidism, cystic fibrosis, sickle cell disease, medium chain acyl-co-A dehydrogenase deficiency, maple syrup urine disease, isovaleric acidaemia, glutaric aciduria type 1, homocystinuria

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2
Q

What is phenylketonuria?

A

Phenylalanine hydroxylase deficiency

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3
Q

What is congenital hypothyroidism?

A

Dysgenesis or agenesis of the thyroid gland

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4
Q

What is specificity?

A

The probability that someone without the disease will correctly test negative

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5
Q

What is sensitivity?

A

The probability that someone with the disease will correctly test positive

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6
Q

What is positive predictive value?

A

The probability that someone who tests positive actually has the disease

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7
Q

What is negative predictive value?

A

The probability that someone who tests negative actually doesn’t have the disease

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8
Q

Name an organic acidaemia

A

Propionic acidaemia, isovaleric acidaemia

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9
Q

Describe the key clinical features of organic acidaemias

A

High urea and ketones, metabolic acidosis. May have a funny smell from organic acids

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10
Q

How are organic acidaemias managed?

A

Low protein diet, acylcarnitine, and haemofiltration

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11
Q

Name one of the nine urea cycle disorders

A

Ornithine transcarbamylase deficiency

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12
Q

Describe the key clinical features of urea cycle disorders

A

High ammonia (>200uM) leading to encephalopathy and developmental delay. Respiratory alkalosis. Vomiting

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13
Q

How are urea cycle disorders managed?

A

Low protein diet to stop urea formation

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14
Q

Name two amino acidopathies

A

Maple syrup urine disease, phenylketonuria

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15
Q

Describe the key clinical features of phenylketonuria

A

High phenylalanine, blue eyes, fair hair and skin, retardation

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16
Q

Describe the key clinical features of glycogen storage disorders

A

Hypoglycaemia, lactic acidosis, hepatomegaly, developmental delay. High risk of hepatoblastoma

17
Q

Describe the key clinical features of galactosaemia

A

Cataracts, hypoglycaemia, neonatal conjugated jaundice

18
Q

How is galactosaemia managed?

A

Low lactose and galactose diet

19
Q

Name a fatty acid oxidation disorder

A

Medium chain acyl CoA dehydrogenase deficiency (MCADD)

20
Q

Describe the clinical features of MCADD

A

Hypoglycaemia, cardiomyopathy, rhabdomyolysis, low ketones

21
Q

How is MCADD screened for?

A

Blood acylcarnitine

22
Q

How is MCADD managed?

A

Regular carbohydrate

23
Q

What are the clinical features of peroxisomal disorders?

A

Poor feeding, seizures, retinopathy, hepatomegaly, mixed hyperbilirubinaemia

24
Q

What are the clinical features of glycosylation disorders?

A

Retardation, nipple inversion

25
Q

How are glycosylation disorders diagnosed?

A

Measure serum transferrins

26
Q

Name a lysosomal disorder

A

Tay Sachs disease

27
Q

Describe the clinical features of lysosomal disorders

A

Very slow progressing neuroregression, hepatosplenomegaly, cardiomyopathy

28
Q

How are lysosomal disorders diagnosed?

A

Urine mucooligopolysaccharides, WBC enzyme levels

29
Q

How are mitochondrial disorders diagnosed?

A

Muscle biopsy

30
Q

Describe the blood test results in mitochondrial disorders

A

High lactate and creatine kinase

31
Q

State three groups of metabolic disorders that lead to accumulation of toxins

A

Organic acidaemias, urea cycle disorders, aminoacidopathies

32
Q

State three groups of metabolic disorders that lead to reduced energy stores

A

Glycogen storage disorders, galactosaemia, fatty acid oxidation disorders

33
Q

State two groups of metabolic disorders that affect large molecule synthesis

A

Peroxisomal disorders, glycosylation disorders

34
Q

What are peroxisomal disorders?

A

Inability to catabolise very long fatty acids or produce bile acids