TUBB4B and primary ciliary dyskinesia: We therefore used CRISPR-Cas9 mediated genome editing to engineer into mice the Tubb4b patient variants carried in PCD-only (p.P259L, p.P259S), syndromic PCD+SND (p.P358S) and SND-only (p.R391H) patients, as well as deletion alleles (Fig. 4A, Fig. S3A, Fig. S10A).