Gene testing for osteonecrosis of the femoral head in systemic lupus erythematosus using targeted next-generation sequencing: A pilot study

Figure 2 Map showing the collagen triple helix repeat domain with collagen type II alpha 1 chain mutations identified in patients with osteonecrosis of the femoral head in systemic lupus erythematosus. Top: Diagram of the collagen type II alpha 1 chain (COL2A1) protein structure. The COL2A1 comprises a von Willebrand Factor C (VWFC) domain (amino acids 34-89), a collagen triple helix repeat domain (amino acids 120-1219), and a fibrillar collagen C-terminal domain (amino acids 1254-1486). Middle: The novel mutations identified in the COL2A1 gene coding sequence in this study are located in exon 8 (encoding amino acids 531-609) and exon 29 (encoding amino acids 1888-1936). Bottom: Mutated nucleotides in exons 8 and 29 of the COL2A1 gene are shown in orange. Mutated amino acids in the VWFC and the collagen triple helix repeat domains of COL2A1 are shown in orange.