At 12 months of age, persistent mild elevations of plasma glycine prompted a switch from IVA Anamix to Valex I. Although we have not found other reports in the literature of elevated glycine in HMG-CoA lyase deficiency, it is well-documented that plasma glycine is elevated in organic acidemias [16], possibly due to suppression of the glycine cleavage complex. Here, HMGCL is linked to inborn organic aciduria.