In a cohort of 40 Greek pregnant women with GDM, four with T2D and 20 healthy pregnant women, significant reductions in the peripheral blood BMAL1, PER3, PPARD, and CRY2 transcript levels were found in the GDM group, supporting the view that disorders of clock gene expression may play a pathogenic role in GDM (Ratajczak et al., 2010). The gene discussed is PER3; the disease is gestational diabetes.