Using CRISPR/Cas9 technology, a G-to-A substitution (C-to-T on forward strand) was created in glutamic acid codon 360 (initially reported as 365) to change it to a lysine codom (p.E360K). The mutation is located in the PR/SET domain and leads to the loss of most of the enzyme's histone methyltransferase activity. As this allele was created in the C57BL/6 strain, it is based on the Prdm9dom2 allele.