TNFRSF11B and systemic sclerosis: Patients with SSc and calcinosis compared to SSc patients without calcinosis may show decreased serum levels of the mineralization inhibitors fetuin-A [23] and inorganic pyrophosphate [38] and, conversely, elevated levels of the mineralization promoter osteoprotegerin [26], suggesting systemic alterations in the extracellular matrix and mineral metabolism associated with this complication.