A study by Wang et al. found 32 differentially expressed genes (DEGs) that were upregulated in the higher BMI twins including DEGs associated with obesity (e.g. NAMPT, TLR9, PTGS2, HBD, and PCSK1N), immunological (e.g., TLR9), and metabolic functions (e.g., PTGS2). This evidence concerns the gene HBD and obesity disorder.