Question

in Hereditary hyperammonemia:

- Define it

- In a table write the types of hyperammonemia & its defective enzyme

- Write about the drug treatment of it

Answer 1

1)Hereditary hyperammonemia is an inherited metabolic urea cycle disorder caused due to deficiency of enzymes needed in urea cycle, due to which excess ammonia levels are present in the blood.

It is a condition characterised by Elenzyme deficiency which are needed for convertion of amino acids to ammonia which is further converted to urea to be excreted out by the kidneys.

It is characterised by poor feeding, lethargy, grunting respiration, seizures, irritability, hyperventilation, failure to thrive etc.

2)

Disorder	type of disorder	Enzyme deficiency	Gene involved
Ornithine transcarbamylase deficiency	X- linked Disorder	Ornithine transcarbamylase	OTC Gene mutation
Arginosuccinic aciduria	autosomal recessive	arginosuccinate lyase	ASL Gene mutation
Cabomyl phosphate synthetase deficiency	autosomal recessive	carbamoyl phosphate synthetase	CPS1 Gene mutation
Argenemia	Autosomal recessive	arginase	ARG1 Gene mutation
Citrullinemia	Aurosomal recessive	arginosuccinate synthetase	ASS1 Gene mutation

3) Treatment of hyperammonemia include following -

I) supportive treatment

a) decreased protein intake in diet and adequate nutritional diet.

b) Dialysis.

c) parenteral nutritional therapy.

II) Medical treatment

It includes drugs - sodium phenylbutyrate

carglumic acid,

sodium phenylacetate,

sodium benzoate

These drugs helps in excretion of ammonia via kidneys. conjugation with either glycine ( example - sodium benzoate ) and glutamine ( example -sodium phenylbutyrate) generates a product which is eliminated by kidneys

For seizures - sodium valproate is used to treat seizures.

III) surgical treatment -

Liver transplantation in severe cases.

An alternative is liver cell transplantation to treat metabolic errors.