ESR1 and Huntington disease: In addition, recent reports have linked PKMTs with the etiology of human diseases, such as cancer,1 Huntington’s disease,2 immunodeficiency syndromes,3 and growth defects.4 Importantly, several PKMTs methylate nonhistone substrates,5 such as the tumor suppressor p53,6 the estrogen receptor ERα,7 the heterochromatin protein HP1α,8 the DNA methyltransferase DNMT1,9 the ATPase Reptin,10 and others.