Ans: a (Ornithine transcarbamoylase deficiency) Ref: Vasudevan, 4th ed, p. 170,171,199In ornithine transcarbamoylase deficiency there will be high level of ammonia in blood.Rate limiting step in urea synthesis is formation of carbomoyl phosphate. It is catalysed by carbamoyl phosphate synthetase I.One molecule of ammonia condenses with CO, in the presence of 2 molecules of ATP to form carbamoyl phosphateNOTE:An entirely different cytoplasmic enzyme carbamoyl phosphate synthetase II is involved in pyrimidine nucleotide synthesis.CPS-I deficiency is related to hyperammonemia type IUrea cycle disorders:DiseaseEnzyme defectHyperammonaemia type IHyperammonaemia type IIHyperornithinaemiaCitrullinaemiaCPS-IOrnithine transcarbamoylaseDefective ornithine transporter proteinArginosuccinate synthetaseOTC deficiency leads to hyperammonaemia type II and not hyperornithinaemia- Galactosaemia is due to deficiency of galactose-1-uridyl transferase and in galactosaemia there will be increased blood galactose level and galactosuria- Histidinaemia leads to accumulation of histidine in blood and body fluids and increased excretion of imidazole pyruvic acid in urine. This is due to deficiency of histidase.- Pheny ketonuria is due to deficiency of phenylalanine hydroxylase.