However, we also observed a trend where genes that cluster in the same ciliary compartment tended to cause a similar phenotype; e.g., mutations in the transition zone genes CC2D2A, TCTN2, TMEM237, and CEP290 almost always resulted in either Joubert or Meckel-Gruber syndrome phenotypes (Fig. 5). The gene discussed is CC2D2A; the disease is Meckel syndrome.