METTL4 is a 472 amino acid enzyme that belongs to the MT-A70-like family. Other members of this family have enzymatic activity that results in the transfer of a methyl group to and from DNA, RNA or amino acids. The gene encoding METTL4 maps to chromosome 18, which houses over 300 protein-coding genes and contains nearly 76 million bases, representing about 2.5% of total DNA in cells. There are a variety of diseases associated with defects in chromosome 18-localized genes, some of which include Niemann-Pick disease, hereditary hemorrhagic telangiectasia, erythropoietic protoporphyria and follicular lymphomas. Also, three chromosomal abnormalities result from meiotic nondisjunction events of chromosome 18: Monosomy 18p, Trisomy 18 (also known as Edwards syndrome) and Tetrasomy 18p.