Here, the CRISPR-Cas9 system was used to generate mouse Kcnj13 null alleles by zygote injection of sgRNA and Cas9 mRNA designed to target the Kcnj13 start codon since a homozygous nonsense mutation has been identified in KCNJ13 in one LCA patient17. The gene discussed is KCNJ13; the disease is Leber congenital amaurosis.