I'm a fan of both Dragon Ball and Megadeth, so I'm surprised that I didn't notice the shared last name sooner. After trying to dig for how, if at all, they were related, I ultimately came up short on both Wikipedia and IMDB. Then I stumbled upon Derek Padula's interview of Mark:
I have a cousin named Don Menza, who is really known in the jazz world, and saxophone.
So they are related! I just found this fascinating, and thought I'd share it here, in case there are any other Megadeth fans around here.Don still lives in North Hollywood, he’s retired now. His son is Nick Menza, the one-time drummer for Megadeath.