Effectiveness of the morpholino targeting mpi was confirmed by the decrease in Mpi enzymatic activity to 27% of controls (Figure 2—figure supplement 1A), which we have previously shown to have no effect on another enzyme in the mannose metabolism pathway, phosphomannomutase 2 (Pmm2)(Chu et al., 2013), and the morphant phenotype could be rescued by either mpi mRNA coinjection or by mannose supplementation (Chu et al., 2013), the latter being the cornerstone of treatment for MPI-CDG patients (Niehues et al., 1998). This evidence concerns the gene PMM2 and congenital disorder of glycosylation.