Oh that one. Well Mass Effect came out only a few months before Doctor Who, so I'd say it's just a serendipitous occasion where they used a similar progression. I doubt Murray Gold played ME2 and decided to rip it off for the major theme of the series that was going to be premiering in weeks.

It's interesting though because it's a lot closer in mood and style to each other than most of the examples of "same melody" song pairings I see. For instance, contrast "Gehn's Theme" from Riven with the same six-note intro used five years earlier for the Overture to Star Trek VI—

https://youtu.be/UwVIwTAwZ-4?t=1m2s

https://www.youtube.com/watch?v=GT-wunjnEXA

They go completely different ways almost right out of the bat.