ENPP1 and arterial calcification, generalized, of infancy, 1: Interestingly, one heterozygous patient who was diagnosed with GACI was found to have the benign ENPP1 p.Arg821His polymorphism (Patel et al., 2004; Stella et al., 2016) in addition to the ABCC6 variant p.Arg1314Trp.