BMP6 and Tangier disease: Selective inhibition of BMP6 signaling abrogates iron-induced up-regulation of hepcidin.27 Hemojuvelin is a BMP6 coreceptor, and it facilitates the binding of BMP6 to its receptor; knockout of the HJV gene markedly decreases BMP6 signaling in hepcidin expression and causes iron overload.28