Isovaleric toan hoá máu là một tình trạng di truyền chuyển hóa hiếm gặp gây ra bởi sự thiếu hụt của các isovaleryl-CoA dehydrogenase enzyme, kiểm soát một bước đầu trong quá trình trao đổi chất của các chi nhánh chuỗi acid amin leucine | GLYCINE Use Glycine is used in the management of isovaleric acidaemia - a rare autosomal recessive inborn error of metabolism. Biochemistry Glycine is a naturally occurring amino acid. In isovaleric acidaemia the administration of additional glycine greatly speeds the conversion of isovaleryl-CoA to isovalerylglycine which is then excreted in the urine. Aspirin should be avoided as it is a competitive substrate for one of the essential metabolic steps involved. Isovaleric acidaemia Isovaleric acidaemia is a rare inherited metabolic condition caused by a deficiency of the enzyme isovaleryl-CoA dehydrogenase which controls an early step in the metabolism of the branch-chain amino acid leucine. A range of metabolites including isovaleric acid then accumulate. Glycine becomes conjugated to isovaleric acid see above and this is then excreted in the urine. Toxicity can be avoided by adhering to a low protein diet and by taking addition glycine by mouth. Some patients present soon after birth often within 3-6 days with poor feeding vomiting and drowsiness. Tremor twitching and seizures may be seen before the child lapses into coma and death. Other patients present for the first time when rather older with similar symptoms precipitated by intercurrent illness. Symptoms are often accompanied by acidosis ketosis and a high blood ammonia level sometimes 500 ụmol l and this can lead wrongly to a urea-cycle disorder being suspected. There may be neutropenia thrombocytopenia and hypo-or hyperglycaemia when the condition first presents in the neonatal period. High isovaleric acid levels may give rise to a characteristic unpleasant odour which has been likened to that of sweaty feet. Patients present very occasionally with progressive generalised developmental delay. The condition is most easily diagnosed by detecting excess isovalerylglycine and 3-hydroxyisovaleric acid in the urine or abnormal acylcarnitines in the blood. The prognosis can be good with early diagnosis glycine .
