What Causes Wrinkled And Saggy Breasts?

i am just wondering of what kinda condition my gf has on her breasts ??? its perhaps either a skin Condition or breast disease . she is 17 and has like configured breasts. her breasts looklike an old womans wrinkled and saggy like a woman of 80 or something. this is a serious question. please give me a answer you would guess or know it was.