A truncated sgRNA (81 (link)) targeting KALRN was designed using CRISPR Design Tool (82 (link)). An sgRNA specific forward primer and a common overlapping reverse PCR primer (SI Appendix, Table S1) were used to generate a T7 promoter containing sgRNA template as described (83 (link)). This DNA template was transcribed in vitro using a MEGAshortscript Kit (Ambion). The Cas9 mRNA was prepared using a MEGAshortscript Kit (Ambion) as described (84 (link)). Following synthesis, the sgRNAs and Cas9 mRNA were purified using the MEGAclear Kit (Ambion), ethanol precipitated, and resuspended in DEPC-treated water. A single-stranded 130 nucleotide DNA repair template (“repair oligo,” reference SI Appendix, Table S1) harboring the knock-in sequence (C→A) as well as a silent mutation (C→T) introducing a unique Hinf1 restriction site was purchased as polyacrylamide gel electrophoresis purified Ultramer DNA (Integrated DNA Technologies). Final codon change was from CCC (wild-type) to ACT (knock-in). The oligo was complementary to the nontarget strand (85 (link)).