15 Inborn errors of metabolism

Question 1

What causes acute hyperammonaemia toxicity?

What are the clinical effects? (7)

Answer 1

Defects in the urea cycle.

Lethargy, poor feeding, vomiting, tachypnoea, convulsions, coma, death.

Question 2

What accumulates in acute porphyria?
What are the possible signs? (9)
(Haem production problem).

Answer 2

ALA (a porphyrin).
Severe abdominal pain. D+V. Palpitations. High blood kPa. Anxiety. Breathlessness. Mental changes. Paralysis. Red/brown urine.

Question 3

What accumulates in photosenstive porphyria?
Signs? (6)
(Haem production problem).

Answer 3

Uroporphrin.

Sensitivity to light. Sudden and painful erythema. Itching. fragile skin, increased hair growth. Red/brown urine.

Question 4

What is androgen insensitivity syndrome?
Effects? (4)
Treatment?

Answer 4

Absent receptors.
Ambiguous genitalia and lack of pubic hair. Primary amenorrhoea and infertility.
Resection of residual gonads.

Question 5

How are inborn errors of metabolism diagnosed?

Answer 5

Pre symptomatic screening.

Question 6

What is homocysteinuria?

Cause?

Answer 6

Insufficient cysteine and methionine (amino acid).

Lack of cystathionine beta-synthase.

Question 7

What are the clinical effects of homocysteinuria? (5)

Answer 7

Mental retardation.
Marfan habitus.
Ectopia lentis.
Osteoporosis.
Thromboembolism.

Question 8

What is mild hyperhomocysteinaemia a risk factor for? (3)

Answer 8

Stroke
Peripheral vascular disease
C oronary artery disease.

Question 9

What do defects in branched chain amino acid catabolism lead to?

Answer 9

Classic organic acidaemias.