Figure 2. Illustration of ultrastructural ciliary defects.

These ultrastructural ciliary defects are characteristic of mutations in genes involved at different steps of cilia assembly and function, including the assembly of the inner and outer dynein arms by cytoplasmic assembly factors. Transmission electron microscopy (TEM) images are shown of a control sample (A, reproduced with permission from Elsevier) and patients with mutations in the following: B. DNAH5, showing defective outer dynein arms (ODAs) (reproduced with permission from Elsevier), C. CCDC40, showing defective inner dynein arms (IDAs) and nexin links (reproduced with permission from Nature Publishing Group), D. LRRC50, showing missing IDAs and ODAs (reproduced with permission from Elsevier), E. CCDC164, showing defects in the nexin- dynein regulatory complex (N-DRC) (reproduced with permission from Nature Publishing Group), and F. RSPH1, showing missing central pair of microtubules (reproduced with permission from Elsevier).