Three of the following letter-clusters are alike in some manner and hence form a group. Which letter-cluster does not belong to that group?

MKOJ URWQ EQGP XFWE

XFWE

MKOJ ⇒ M →(+2)→ O        AND           K →(-1) → J URWQ⇒ U →(+2)→W       AND             R →(-1) → Q EQGP ⇒ E →(+2)→ G       AND             Q →(-1) → P XFWE ⇒ X →(-1)→ W        AND            F→(-1) →E (ODD)