Inborn Errors Of Metabolism

Question 1

What does the mutation in PKU result in?

Answer 1

Phenylalanine cannot be converted to tyrosine

Question 2

Incidence of PKU?

Answer 2

1 in 5000 to 1 in 15000

Question 3

Presenting features of PKU?

Answer 3

Fair hair, developmental delay, eczema, seizures

Question 4

Treatment of PKU ?

Answer 4

LOW protein diet

*avoid aspartime (sweetener)

Question 5

Mutation in cystic fibrosis?

Answer 5

Delta F508 on Ch7 in CFTR gene encoding Cl transporter

Question 6

Heelprick test for CF?

Answer 6

Immune Reactive Trypsin

Question 7

Carrier rate for CF?

Incidence rate?

Answer 7

1 in 25 carriers

1 in 2500 affected

Question 8

Gold standard for diagnosing sickle cell?

Answer 8

Hb electrophoresis

Question 9

SCD incidence rate?

Answer 9

1 in 2000

Question 10

MCADD stands for?

Answer 10

Medium chain acyl CoA dehydrogenase deficiency

Question 11

Disorder in MCADD?

Answer 11

Disorder of mitochondrial fatty acid beta oxidation where there is decreased acyl coA synthesis (needed for Krebs)

Therefore cannot breakdown fat

Results in hypoglycaemia and cot death

• 1 in 10000

Question 12

Diagnosis of MCADD?

Answer 12

Acylcarnitine levels

Tandem mass spectrometry (MSMS)

Question 13

Vomiting without diarrhoea

Hyperammonia

Respiratory alkalosis

Encephalopathy

All characteristic of?

Answer 13

Urea cycle defects

7 in total

Question 14

Mode of inheritance?

Answer 14

Autosomal recessive except OTC (x linked)

*ornithine transcarbamylase deficiency)

Question 15

Cheesy/sweaty smell
Lethargy
Feeding problems
Truncal hypotonia with limb hypertonia 
Myoclonic jerks

Characteristic of?

Answer 15

Organic acidurias

Question 16

Give an example of an organic aciduria?

Answer 16

Maple syrup urine disease

Also isolvaleric acidaemia
Reye’s syndrome

Question 17

Blood abnormality in organic aciduria patients?

Answer 17

Hyperammonia with metabolic acidosis (high anion gap)

Question 18

Which amino acids are particularly affected in organic acidurias?

Answer 18

Leucine, isoleucine, valine

Branched amino acids

Question 19

Inheritance of galactosaemia?

Answer 19

Autosomal recessive

Question 20

Enzyme deficiency of galactosaemia?

Answer 20

GAL-1-PUT

*cannot break down lactose to glucose and galactose

Question 21

Tests for galactosaemia?

Answer 21

Urine reducing substances

Red cell GAL-1-PUT

Benedicts reagent and Fehlings test

Question 22

Presentation of Galactosaemia?

Answer 22

Neonatal jaundice with conjugated hyperbilirubinaemia

Hepatomegaly

Hypoglycaemia

Sepsis

Question 23

How many types of glycogen storage disorder?

Answer 23

11

Question 24

Type 1 GSD?

Answer 24

G6PD (Von Gierke’s)

Question 25

Type 5 GSD?

Answer 25

McArdles

Question 26

Presentation of GSD?

Answer 26

Lactic acidosis
Convulsions

Hypoglycaemia
Hepatomegaly
Hyperlipidaemia

Question 27

Fair skin, brittle hair, lens dislocation, VTE

Answer 27

Homocysteinuria

*cystathione synthase deficiency

Question 28

Treatment for homocysteinuria?

Answer 28

Low methionine diet

Question 29

Urine mucopolysaccharides with organomegaly, dysmorphia and regression?

Answer 29

Lysosomal storage diseases

Question 30

MELAS?

Answer 30

Mitochondrial encephalopathy, lactic acids and stroke

Question 31

Enzyme deficiency in Phenylketonuria?

Answer 31

Phenylalanine hydroxylase