KCNQ1 and diabetes mellitus: In diabetes patients, the levels of DNA methylation with the rs231840 TT genotype were significantly lower than with the other variant alleles.[12] The level of methylation of the KCNQ1 gene imprinted gametic differentially methylated domains, as a key regulator of placental function, was associated with trophoblastic giant cell expansion.[23] We have not learned how the KCNQ1 gene influences the onset of preeclampsia, but we did find that it played an essential role in controlling the vascular tone and responses to altered oxygenation.[15,22]