Knows how to play, but has no interest

[Guest guest]

My 4.5 year old son, who is high functioning, has been learning to

play with toys through ABA. Although he is able to demonstrate skills

when asked to do so, he shows little to no interest in play. He

understands what pretending is, can be any animal you ask him to be,

and learns very quickly when shown how to play with a new toy. He

just

doesn't seem to care. He would rather sit and draw letters and

numbers, or play the computer. He likes it when we pretend his

letters

and numbers are playing with eachother, but doesn't care for real

toys. Any suggestions?