MGP and Pseudoxanthoma elasticum: The first of two publications described a PXE-like syndrome caused by a deficiency in gamma-glutamyl carboxylase (GGCX) (Vanakker et al., 2007) and a second article reported a deficit in the carboxylation (activation) of Gla proteins, including the calcification inhibitor Matrix Gla Protein (MGP), secondary to reduced vitamin K levels in the circulation of PXE patients (Vanakker et al., 2010).