Inclusion Criteria:  Male or female participants aged 18 to 75 years  Participants (approximately 1 carrier and 1 normal to match proband)  Confirmed PXE participants: index PXE/proband with established PXE and ABCC6 mutations identified PXE carrier participants: biological sibling of the PXE index case and confirmed as PXE carrier Non-PXE normal participants: biological sibling of PXE index case and confirmed as non-PXE normal  Exclusion Criteria:  Unconfirmed ABCC6 mutation status Use of bisphosphonate in the preceding 12 months and during the study Use of Vitamin B6 and/or Vitamin D supplement in the preceding 1 month and during the study (if the total Vitamin B6 supplementation is >5 mg/day) Recent initiation or dose change of Vitamin D and/or multivitamin supplement in the preceding 1 month and during the study Bone fracture within 3 months prior to Screening or active bone disease (excluding osteopenia or osteoporosis) History of hyperparathyroidism History of moderate to severe renal impairment History of hypophosphatasia Known history of uncorrected abnormality in calcium (Ca), phosphate, alkaline phosphatase (ALP) or parathyroid hormone Other significant condition (medical, psychiatric, social, or medication) that, in the judgment of the Investigator, would prevent full participation or would be inappropriate for the study