What kind of problems do pitbull Lab Great Dane mixes have?

i have a Pit bull Great Dane Lab mix named Yakuza hes a little over 2 years old now. he seems fine and hes not aggressive unless my dad or i give him his attack command but im wondering what kind of health problems he might have as he gets older... i mean he is not a small dog in the least so i figured their might be some join or muscle problems but what would they be and how severewould they be... and what can i do to make sure that ddoesn'thit for a long time?