Arginine codon 80 (AGG) in exon 4 was changed to leucine (CTT) (p.R80L) using sgRNAs (targeting GAGGAGGATAAAGCCCGAAG and TGACTCACAGCAAGTCTGGG) and an ssODN template with CRISPR/Cas9 technology. R80 is essential for matriptase-mediated cleavage of the encoded peptide. (J:340720)