I don't know. I work in his school and a little while back, all staff were sent the G&T list, which is how I discovered D's was on it. (That was a weird moment!)
He's 6, reads the same books as my very able 9 year old and understands them. I'm not yet sure if he gets inference. He's very good at maths and very interested in all things scientific. He seems to be able to grasp concepts really quickly and can explain them clearly.
His scissor skills are rather poor and his drawings are very basic. They're OK for the young year 2 he is, but not at the level of the rest of his brain, thus proving that you can't be good at everything. 
He's a quirky, happy little chap.
School are really good at differentiating,so he doesn't get bored. I worry that he will one day, though. Or he may level out, who knows? So long as he never frames his brains for granted and just coasts, I don't mind.