*2.2. Sample Evaluation*

Serum was separated and stored in an ultrafreezer at −80 ◦C. Indirect immunofluorescence was used for antinuclear antibodies analysis (ANA). Commercial enzyme linked immunosorbent assay (ELISA) kits were used to determine anti-Scl70 and anti-centromere antibodies (Euro Diagnostica, Malmo, Sweden).
