Arginine codon 279 (AGG) and leucine codon 282 (CTT) in exon 8 were changed to valine (GTG, GTT) (p.R279V, p.L282V) using an sgRNA (targeting GAAGTCAAGGACCATCCTTGAGG) and ssODN template with CRISPR/Cas9 technology. These mutations block processing of the encoded peptide by FURIN (paired basic amino acid cleaving enzyme) and site 1 membrane-bound transcription factor peptidase (MBTPS1). (J:324586)