Tyrosine codon 402 (TAT) in exon 13 was changed to phenylalanine (TTT) (p.Y402F) using an sgRNA and an ssODN template (GGGCTGGGCCCCTTTCTGTCATTACAGAGTCAGACATCTTTGCAGAGATTCCCGATGAGACCCTGCGAAGACCAGGAGG) with CRISPR/Cas9 technology. This mutation prevents autophosphorylation of the residue in the encoded peptide.