Since recent studies indicate the involvement of GRP and MGP in calcification defects, where for example GRP serves as marker for kidney dysfunction in CKD patients [PMID: 32120910], levels of under-carboxylated and γ-carboxylated GRP along with MGP and BGLAP should be used as a biomarker in VKCFD1 patients as well. Here, GRP is linked to chronic kidney disease.