Craft a musical piece that integrates the provided melodic theme and the corresponding alphabetical pattern.
X:1
L:1/4
M:3/4
K:G
['F G']  
X:1
L:1/4
M:3/4
K:G
 d d c | _B A G | F G A | D2 d | _e d c | _B A d | D2 F | G z d | d d c | _B A G | F G A | D2 d | 
 _e d c | _B A d | D2 F | G z d | D2 F | G z d | D2 F | G z d | _e d c | _B A d | D2 F | G z d | 
 D2 F | G z d | D2 F | G z2 |]  