ABSTRACT
OBJECTIVE@#To investigate the incidence,clinical,biochemical and genetic characteristics of isovaleric acidemia (IVA) in Zhejiang province.@*METHODS@#Between January 2009 and December 2019, a total of 3 510 004 newborns were screened for IVA using tandem mass spectrometry. Patients of IVA were confirmed by urine organic acid and @*RESULTS@#A total of 15 patients with IVA were diagnosed, with an incidence of 1/234 000. Three patients had acute neonatal IVA, and the rest were asymptomatic. The isovalerylcarnitine (C5) levels were increased in all patients. Twelve children underwent urinary organic acid analysis, of which 11 cases had elevated isovalerylglycine levels, 4 cases with 3-hydroxyisovalerate increased simultaneously. Eleven IVA patients underwent genetic testing, 9 patients were compound heterozygous variants in @*CONCLUSIONS@#The clinical manifestations of IVA are non-specific, and the gene spectrum is scattered. Newborn patients screened by tandem mass spectrometry can receive early diagnosis and treatment, so as to correct metabolic defects and pathophysiological changes.
Subject(s)
Child , Humans , Infant, Newborn , Amino Acid Metabolism, Inborn Errors/epidemiology , China/epidemiology , Isovaleryl-CoA Dehydrogenase/genetics , Mutation , Neonatal Screening , Tandem Mass SpectrometryABSTRACT
Objective To explore the clinical, therapeutic and genetic features of IVD gene in late-onset non-classical isovaleric aciduria. Methods One boy and two girls presented with intractable vomiting were admitted. Urine organic acids and blood acylcarnitines proifles were analyzed. Isovaleric aciduria was diagnosed and conifrmed by IVD gene analysis. The patients were treated with leucine-restricted diet and the supplements of L-carnitine and glycine. Results Three patients had recurrent vomiting, drowsiness, odor of sweaty feet and metabolic acidosis from the age of 1 to 2 years. All of them had normal intelligence and leukopenia. One had oligocythemia. The blood isovalerylcarnitines (4.6 to 8.2μmol/L) and urine isovalerylglycines (36.1 to 1783.56 mmol/mmol creatinine) were elevated. Six mutations were found in their IVD gene. Four mutations (c.157C>T, c.214G>A, c.1183C>G and c.1208A>G) were reported. Two (c.1039G>A and c.1076A>G) were novel. The patients completely recovered after treatment with protein-restricted diet and the supplements of L-carnitine and glycine. Currently, they were aged 19 months to 14 years with normal physical and psychomotor development. Conclusions The clinical features of late-onset non-classical isovaleric aciduria are complex. It is onset in infants and young children and characteristic of recurrent vomiting and metabolic acidosis, which can be diagnosed by the blood acylcarnitine spectrum, urine organic acid analysis, and conifrmed by genetic analysis. L-carnitine supplement and diet intervention has signiifcant effects.