CYP21A2 and metabolic disease: In the transcriptomes of sterile fish, seven genes showed the greatest upregulation and played important roles in steroid biosynthesis and in the Jak-stat signaling pathway: CYP11A1, CYP11B2, CYP17, CYP21, HSD3B, BCL2L1, and PRLR. Other researchers have confirmed that the variation in the expression of genes for steroid biosynthesis can affect hormone levels and cause metabolic disorders.