Identification of a Novel Mutation in the MCCC2 Gene of a Korean Patient with 3-Methylcrotonyl-CoA Carboxylase Deficiency

3-methylcrotonyl-CoA carboxylase deficiency is an autosomal recessive disorder characterized by a defect in leucine catabolism. We report the case of an 80-day-old patient with 3-methylcrotonyl-CoA carboxylase deficiency who had elevated levels of 3-hydroxyisovalerylcarnitine (45.56 micromol/L; reference range, C (p.Gly105Arg)] at nucleotide position 313 and a mutation caused by a heterozygous A to T transversion [c.1252A>T (p.lle418Phe)] at nucleotide position 1252. Identification of these 2 novel MCCC2 gene mutations in our patient suggested that analysis of the MCCC1 and MCCC2 genes might prove useful in the diagnosis of 3-methylcrotonyl-CoA carboxylase deficiency.