Novel mutations in the IVD gene identified in Korean patients with isovaleric acidemia. (a) A G–T transversion at the consensus splicing donor site in the intron 1, (b) a G–T transversion at nucleotide 149 in exon 2 resulting in the substitution of Arg21 with Leu (Arg50Leu based on the precursor reference protein, NP_002216), (c) a CA–GG replacement at the consensus splicing acceptor site in intron 4, (d) an A–G transition at nucleotide 832 in exon 8 resulting in the substitution of Ser249 with Gly (Ser278Gly based on the precursor reference protein, NP_002216), (e) a T–G transversion at nucleotide 1135 in exon 11 resulting in the substitution of Phe350 with Val (Phe379Val based on the precursor reference protein, NP_002216).