Clinical Cases Of Protein Metabolism

Question 1

Urea cycle disorder

Answer 1

Symptoms
1) Vomitting, lethargy, restlessness and aversion to protein containing diet
2) Mental retardation
3) High ammonia and ornithine level
4) Low citruline level
5) Orotic acid present in urine

Enzyme deficient is Ornithine transcarboamylase.

Question 2

Phenylketonuria

Answer 2

Signs
1) Generalised fits
2) Delayed milestones and lethargic
3) Grey coloured hair and light coloured skin.
4) Mousy odour in urine

Enzyme deficient is phenylalanine hydroxylase

Colour of skin and hair is due to lack of melanin which is synthesized from tyrosine which in turn is synthesized from phenylalanine.

Alternate products formed in phenylketonuria are phenylpyruvate, phenylacetate and phenyllactate.

Malignant phenylketonuria occurs when synthesis of tertrahydrobiopterin is affected.

Mousy odour is due to phenylacetate.

Treatment is by restriction on phenylalanine and supplementation of tyrosine.

Question 3

Albinism

Answer 3

Signs:
1) Difficulty in visualising distant objects
2) Involuntary movements in both eyes which is nystagmus.
3) Skin irritation and redness when exposed skin to sun.
4) White skin and light brown hair.

Enzyme deficient is tyrosinase.

Patient with albinism may have nystagmus, strabismus and decreased visual acuity.

Care by applying sunscreen before going out.