In the BMP-SMAD signaling, ALK2 as primary endogenous BMP type I receptors is involved in systemic iron regulation; miR-130a targets 3′UTR of ALK2 to inhibit BMP-SMAD signaling and the expression of hepcidin; it was upregulated in the iron deficiency mice [105]. The gene discussed is ACVR1; the disease is nutritional disorder.