As a rare autosomal dominant hypopigmentation disease, piebaldism is characterized by the presence of patchy albinism on the skin, and is mainly caused by the loss-of-function mutations in c-KIT gene. Congenital hearing loss is occasionally found as an expanded syndrome of piebaldism. However, the correlation between c-KIT mutations and piebaldism with hearing loss has not yet been described. Herein, we created a mutant strain of miniature pig through the N-ethyl-N-nitrosourea (ENU)-mediated mutagenesis, which showed severe piebaldism and congenital profound hearing loss. A genome-wide association study (GWAS) linked these phenotypes to the c.2430T>A transition mutation in exon 17 of c-KIT, resulting in an Asp810Glu substitution in the tyrosine kinase domain. The Asp810 was localized at the highly conserved DFG motif and the transition from Asp to Glu would deplete the kinase activity of c-KIT protein, finally inducing the degeneration of intermediate cells and hair cells in inner ear. The c-KITc.2430T>A/+ pig is the first large animal model with a c-KIT loss-of-function mutation, showing piebaldism with hereditary hearing loss. It will serve as an experimental model for exploring the function of c-KIT during biological processes and the candidate therapies for c-KIT mutations related diseases.

Precise gene edition is required for modeling human diseases in model organisms. In this study, by using in vitro transcribed CRISPR RNA reagents and double cuttings by CRISPR/Cas9 at two sites flanking pig GJB2 (pGJB2) CDS with long single-stranded DNAs (lssDNA) as homology-directed repair (HDR) templates, we generated two gene-edited pigs of which GJB2 CDSs were replaced with a human GJB2 (hGJB2) CDS containing c.235delC mutation and a pGJB2 CDS containing p.V37I mutation both commonly observed in hearing loss patients, respectively. Genotyping showed that the HDR-derived mutation efficiencies in founders were as high as 80% (4/5) and 50% (2/4), respectively, while no mutation was observed in the group of single cutting with one sgRNA covering the 235th nucleotide C in pGJB2 CDS using a short single-stranded oligo DNA (ssODN) containing c.235delC mutation as HDR template. Besides, the HDR-derived mutations were extensively integrated into various tissues in founder and capable of germline transmission. This study indicated that the “two cuttings with lssDNA templates” method, which expands sgRNA selection scope and avoids direct cutting of gene CDS, can precisely introduce human mutations into mammalian genomic sites, especial those resistant to gene editing, with CRISPR RNAs instead of rebonucleoproteins used in previous reports.