1. Department of Pediatrics, University of Pittsburgh School of Medicine, UPMC Children’s Hospital of Pittsburgh, 4401 Penn Ave., Pittsburgh, PA 15224, USA
2. School of Medicine, Tsinghua University, Beijing 100084, China
3. UPMC Scleroderma Center, University of Pittsburgh, Pittsburgh, PA 15224, USA
4. UMMG Department of Pathology, Miller School of Medicine, Medical Campus, University of Miami, 1550 NW 10th Ave. #118, Miami, FL 33136, USA
5. Department of Biostatistics, University of Pittsburgh, Pittsburgh, PA 15224, USA