A study using a cell-based study reported that anti-Caspr2 Ab from the patients with LE and PNH did not induce internalization of Caspr2, but rather interfered with the binding of Caspr2 to TAG-1/contactin-2 in hippocampal neuron cultures, which resulted in interference with the clustering of juxtaparanodes and in hyperexcitability [28]. The gene discussed is CNTN2; the disease is paroxysmal nocturnal hemoglobinuria.