CRISPR-Cas9-Generated TXNDC15 c.560delA Homozygous Mouse Model Exhibits Meckel-Gruber Syndrome Phenotype

To determine whether TXNDC15 variation causes Meckel-Gruber syndrome (MKS), we assessed the pathogenicity of the frameshift variant c.560delA. A CRISPR-Cas9 generated mouse model carrying the equivalent Txndc15 c.512delA mutation was analyzed at embryonic day 15.5. Homozygous Txndc15^mt/mt embryos displayed the complete MKS phenotype-fetal lethality, exencephaly, omphalocele, post-axial polydactyly, and polycystic kidneys-together with markedly reduced TXNDC15 protein in brain, liver, and kidney. These findings confirm TXNDC15 as a bona fide MKS disease gene.