In addition, a direct correlation between Shh-signalling disruption, defective granule cell progenitor proliferation, and cerebellar hypo/aplasia in individuals with Joubert and Meckel syndrome has been described.34, 36 While the cerebellar involvement is consistent with the cilia defect, the major signal enhancements in the periventricular and subcortical white matter (figure 1Ad–f) is not usually seen in patients with ciliopathies. The gene discussed is SHH; the disease is ciliopathy.