By inspecting whether the reduction in the primary cilium length is proportionally related to a reduction in soma size, we found that Mecp2 null neurons exhibit the well‐known reduction in the soma area that is not present in RTT patients’ fibroblasts; however, in both cell types no correlation exists between primary cilium length and soma size (Appendix Fig S1). This evidence concerns the gene MECP2 and Rett syndrome.