Rafael signs new deal while Fabio joins QPR
"Rafael is one of our brightest young prospects. He has no fear of playing and has great belief in himself," manager Sir Alex Ferguson told the club's website on Monday.
"The boy has developed immensely since joining United [in 2008], his energy and enthusiasm are a joy to watch. Rafael has all the attributes to become one of the best full-backs in the world and I am delighted he has signed a new contract."
Full-back Fabio, who is also a member of United's first-team squad, will link up with his new Rangers team-mates on the first day of pre-season training next Monday.
"This is a great opportunity for us to loan a good young player who has decent experience of playing for a top club like Manchester United," said Rangers manager Mark Hughes.
The two brothers turn 22 next Monday.