Proline codon 216 (CCA) in exon 5 was changed to leucine (CTA) (p.P216L) using an sgRNA and an ssODN template with CRISPR/Cas9 technology. The mutation is the equivalent of the human p.P214L (c.641C>T) mutation associated with the autosomal dominant syndrome of thrombocytopenia and leukemia predisposition. (J:342734)