▁mut ations ▁associated ▁with ▁C MS , ▁more ▁than ▁half ▁are ▁mut ations ▁in ▁one ▁of ▁the ▁four ▁gen es ▁encoding ▁the ▁adult ▁ac et yl ch oline ▁re ceptor ▁sub un its . ▁Mut ations ▁of ▁the ▁A Ch R ▁often ▁result ▁in ▁end plate ▁def ic iency . ▁Most ▁of ▁the ▁mut ations ▁of ▁the ▁A Ch R ▁are ▁mut ations ▁of ▁the ▁CH R NE ▁gene . ▁The ▁CH R NE ▁gene ▁codes ▁for ▁the ▁e psilon ▁sub unit ▁of ▁the ▁A Ch R . ▁Most ▁mut ations ▁are ▁aut os om al ▁re cess ive ▁loss - of - function ▁mut ations ▁and ▁as ▁a ▁result ▁there ▁is ▁end plate ▁A Ch R ▁def ic iency . ▁CH R NE ▁is ▁associated ▁with ▁changing ▁the ▁kin etic ▁properties ▁of ▁the ▁A Ch R . ▁One ▁type ▁of ▁mut ation ▁of ▁the ▁e psilon ▁sub unit ▁of ▁the ▁A Ch R ▁introdu ces ▁an ▁Arg ▁into ▁the ▁binding ▁site ▁at ▁the ▁α / ε ▁sub unit ▁interface ▁of ▁the ▁re ceptor . ▁The ▁addition ▁of ▁a ▁c ation ic ▁Arg ▁into ▁the ▁an ionic ▁environment ▁of ▁the ▁A Ch R ▁binding ▁site ▁greatly ▁reduces ▁the ▁kin etic ▁properties ▁of ▁the ▁re ceptor . ▁The ▁result ▁of ▁the ▁newly ▁introduced ▁AR G ▁is ▁a ▁ 3 0 - fold ▁reduction ▁of ▁ag on ist ▁aff inity , ▁ 7 5 - fold ▁reduction ▁of ▁g ating ▁efficiency , ▁and ▁an ▁extremely ▁weak ened ▁channel ▁opening ▁probability . ▁This ▁type ▁of ▁mut