MPL and hyperinsulinemic hypoglycemia, familial, 4: In patients with congenital amegakaryocytic thrombocytopenia, a condition characterized by a lack of megakaryocytes and PLTs due to c-MPL deficiency, the level of plasma TPO is significantly increased.9This suggests that c-MPL plays a crucial role in the negative feedback regulation of TPO levels and that its absence can lead to dysregulation of TPO production.