PAX8 and hypothyroidism: The second group displayed a severe phenotype comparable to that observed in age-matched Pax8(Cre/+); Dicerflox/flox mice, with hypothyroidism associated with low T4 plasma levels (0,47±0,386 μg/dl, Figure 4B), disruption of thyroid architecture (Figure 4E) and post-weaning lethality.