DNMT1 and immunodeficiency disease: For example, mutations in DNA Methyltransferase 3b (DNMT3b) are implicated in Immunodeficiency, Centromere instability and Facial anomalies (ICF) syndrome2, mutations in DNA Methyltransferase 3a (DNMT3a) are found in acute myeloid leukemia (AML) patients3 while those in DNA Methyltransferase 1 (DNMT1) cause autosomal dominant cerebellar ataxia, deafness and narcolepsy4.