HHH syndrome is due to defect in:-
HHH syndrome is due to defect in Ornithine permease of mitochondrial membrane. Hyperornithinemia: As ornithine can't enter mitochondria, it accumulates in blood. Hyperammonemia: As ornithine is not available, urea cycle can't operate i.e. NH3 can't be detoxified. Homocitrullinuria: As ornithine is not available, ornithine homologue lysine reacts with Carbamoyl phosphate to produce homocitrulline. (Difference between lysine and ornithine is just one CH2 group)
Ornithine transcarbamoylase
Ornithine permease
Ornithine decarboxylase
Ornithine
Urea cycle