LRP4 and myasthenia gravis: In the most updated classification, Berrih-Aknin and coworkers reported that approximately 90% of the total MG patients show anti-AChR antibodies, that 5% of MG patients have anti-MuSK antibodies and ascribe anti-LRP4 antibodies to the 2% of the remaining 5% dSN-MG (range 12–50% of seronegative population) [4].