The hyperspin mutation is a spontaneous 123.6 kb deletion of Chromosome 6: 5.86-6.66 Mb (GRCm38) that begins in intron 3 of Slc25a13 and ends in exon 17, an interval that includes an enhancer of Dlx5 and, in addition to creating a null allele of Slc25a13, diminishes otocyst expression of Dlx5. (J:254776)