CRISPR/Cas9 technology introduced a G to A change at position 3452 (c.3452G>A) resulting in an arginine to glutamine substitution at residue 1151 (p.R1151Q) corresponding to the most common gain of function human R1154Q mutation seen in individuals with Catnu syndrome. Unexpected mRNA splicing leads to an in-frame deletion of exon 28 and loss of functional protein.