Leptin has also been shown to down-regulate bone resorption process by inhibiting osteoclastogenesis and osteoclast activity8,12,19 Given the importance of leptin in directly stimulating bone formation and inhibiting bone resorption, the observed hyposensitivity to leptin in AIS could lead to an imbalance in these normally coupled processes, resulting in down-regulated bone formation and up-regulated bone resorption, and the low bone mass and deranged bone quality that were found in AIS girls. Here, LEP is linked to androgen insensitivity syndrome.