OROTIC ACIDURIA- Pyrimidine disorder
OROTIC ACIDURIA
- It is a rare autosomal recessive condition.
- It is due to the deficiency of UMP synthase, a bifunctional enzyme having-
- Orotate phosphoribosyl transferase
- Orotic acid decarboxylase (orotidylate decarboxylase)
- It is characterized by excretion of uric acid in urine.
- Two types-
- Type I oroctic aciduria- deficiency of orotate phosphoribosyl transferase and orotic acid decarboxylase
- Type II orotic aciduria- deficiency of orotidylate decarboxylase.
Clinical features–
- Retarded growth
- Developmental retardation
- Megaloblastic anaemia
- Increased excretion of uric acid in urine
Treatment-
- Allopurinol
- 6 –Azauridine
- Diet rich in Uridine or cytidine is an effective treatment
Rey syndrome and Orotic Aciduria-
- Considered as secondary orotic aciduria.
- Rey syndrome is a defect in ornithine transcarbomylase (Urea cycle) causes increased cytosolic pool of carbamoyl phosphate.
- Leads to excretion of orotic acid.
Exam Important
1.Synthetic nucleotide used in the treatment of AIDS- Zidovudine.
2. The bifunctional enzymes deficient in orotic aciduria are
> orotate phosphoribosyl transferase
> Orotic acid decarboxylase (orotidylate decarboxylase)
3.Type II orortic aciduria is caused due to deficiency of Orotic acid decarboxylase (orotidylate decarboxylase)
4. 6-Azauridine (after its conversion into 6-azauridylate) also cause orotic aciduria and orotinuria by inhibiting orotidylate decarboxylase.
5. orotate phosphoribosyl transferase and Orotic acid decarboxylase (orotidylate decarboxylase) together called as UMP Synthase.
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