A single CRISPR guide RNA was designed to target the coding sequence of exon 2 before the transmembrane region. This allele was generated by injecting the guide RNA and Cas9 mRNA into the pronucleus and cytoplasm and an allele containing a 2-bp insertion (GT into exon 2) that disrupts the ORF after codon 16 was chosen. This mutation is expected to produce a truncated protein lacking the transmembrane domain. (J:229305)