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

Figure 1 Map showing the nitric oxide synthase N-terminal domain with nitric oxide synthase 3 mutations identified in patients with osteonecrosis of the femoral head in systemic lupus erythematosus. Top: Diagram of the nitric oxide synthase 3 (NOS3) protein structure. Nitric oxide synthase (NOS) comprises a NOS N-terminal domain (amino acids 121-481), a flavodoxin/NOS domain (amino acids 522-698), a flavin adenine dinucleotide-binding, type 1 domain (amino acids 752-979), and an oxidoreductase flavin adenine dinucleotide/nicotinamide adenine dinucleotide (P)-binding domain (amino acids 1011-1123). Middle: The novel mutation of the NOS3 gene coding sequence identified in this study, located in exon 6 (encoding amino acids 675-816). Bottom: Mutated nucleotides in exon 6 of NOS3 are shown in orange. Mutated amino acids in the NOS N-terminal domain of NOS3 are shown in orange. FAD-binding: Flavin adenine dinucleotide-binding; NAD: Nicotinamide adenine dinucleotide.