A systematic review and meta-analysis demonstrated that the levels of serum malondialdehyde, nitric oxide and total oxidant were increased, while superoxide dismutase, catalase and glutathione peroxidase were reduced in patients with AA.[16] OS induces the expression of MICA (MHC class I-related chain A) in HF cells, which leads to the collapse of immune privilege and T cell attack.[16] VD supplementation is indirectly involved in the synthesis of antioxidants and prevent OS by regulating the expression of Klotho and Nrf2.[16]. This evidence concerns the gene MICA and hydrops fetalis.