The 5' end of exon 4 was targeted with sgRNAs (targeting ATTGGATTTCCATATTCTCT and ATATATGGATCTGACATTGG) using CRISPR/Cas9 technology, resulting in a 40 bp deletion. This allele occurs in conjunction with the Ythdf1em1Jhha, Ythdf1em3Jhha and Ythdf2em1Jhha alleles in the same ESC line. (J:299108)