Fig. 4

a A new Smchd1 loss-of-function allele was generated using CRISPR/Cas9. This produced a 6 nt deletion including the splice donor site of intron 3. This resulted in a number of aberrantly spliced transcripts. The protein variation listed is the smallest in-frame mutation detected, a 14 amino-acid deletion including the catalytic residue of the GHKL ATPase domain p.E147. b Western blot from heads of E10.5 embryos show a markedly reduced level of SMCHD1 protein in the Δ6nt/Δ6nt, which runs slightly faster than wildtype SMCHD1. n = at least 5 embryos per genotype. c Observed and expected numbers of pups born of each genotype. Axial skeletal patterning analysis of + /+ and Δ6nt/+ animals. Homeotic transformations observed in the animals are marked in red in the schematic (d). Transformations include C7 → T1, T13 → L1 and L6 → S1. C7 rib is labelled with a *, the missing T13 rib is marked with an arrow and the hypomorphic T13 rib is labelled with an arrowhead. Number of animals analysed with each phenotype are in (e). Animals showing any of the homeotic transformations are considered as transformed. Most Δ6nt/+ animals show all of the homeotic transformations marked in (d). Scale bar = 500 µm.