This may be significant with respect to the methemoglobinemia as porcine erythrocytes use hepatically derived inosine as a substitute for glucose for glucose (Watts et al., 1979) and it has been shown, in vitro, that inosine is used to efficiently generate NADH for the enzymatic reduction of methemoglobin in pig erythrocytes (Sartorelli et al., 1996). Here, HBG2 is linked to methemoglobinemia.