These cases confirm that MEGF8-associated CRPT2 shares many core features of RAB23-associated CRPT1, but differences include a significantly higher frequency of left-right patterning abnormalities, and lower frequency of multi-suture craniosynostosis in the MEGF8-associated condition, refining the phenotypic spectrum of this rare condition. The gene discussed is RAB23; the disease is craniosynostosis.