ACADVL and very long chain acyl-CoA dehydrogenase deficiency: Arg450His showed 5% normal-to-low residual VLCAD activity at 30°C; however, the p.Arg450His variant had no significant activity at 37°C, indicating that the homozygous p.Arg450His variant is a mild variant sensitive to temperature in vitro, which may be associated with the milder phenotype of VLCADD (Fukao et al., 2001; Li et al., 2020).