MCCC2 유전자의 새로운 변이에 의한 3-Methylcrotonyl-CoA Carboxylase 결핍증

Abstract

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 (45.56μmol/L; reference range, <0.65 μmol/L), which was detected using tandem mass spectrometry during newborn screening, and elevated levels of 3-hydroxyisovaleric acid (375.75 mmol/mol Cr) and 3-methylcrotonylglycine (502.36 mmol/mol Cr ), which were detected in urine organic acid analysis. We performed direct sequence analysis of all the exons of the MCCC1 and MCCC2 genes. No mutations were detected in the direct sequence analysis of MCCC1. However sequencing of the MCCC2 gene revealed a mutation caused by a heterozygous G to C transversion [c.313G>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.