For instance, mutations in X-chromosomal Mct8 result in severe thyroid pathologies with nuclear characteristics of papillary thyroid carcinoma (PTC), indicating dedifferentiation of thyrocytes in male Mct8-deficient animals (Mct8−/y) that leads to massive thyrocyte hyperproliferation [10]. The gene discussed is SLC16A2; the disease is thyroid gland disorder.