This gene encodes a protein that can catalyze transfer of either UDP-glucose or UDP-xylose to epidermal growth factor (EGF) repeats, such as those found in Notch. Loss of this gene product results in embryonic lethality. Embryos have neural plate defects, heart defects, and truncations of their posterior axis. Alternate splicing results in multiple transcript variants. [provided by RefSeq, Jul 2014]