Es gibt so reichlich Google-Treffer, dass 'knowledge gap' = supported.
Bei meiner Recherche fiel mir 'Wissenskluft' auf (nicht in Leo), und Wissenskluft und -lücke scheinen in vielen Fällen nicht identisch zu sein, vergl. wikipedia-link. Gibt es eine entsprechende Unterscheidung auch auf englisch?

I'd argue that 'a gap in ones knowledge' is definitely correct & shouldn't be removed, a 'knowledge gap' is probably also OK - potentially more AE than BE though. Its difficult to argue based on google hits because 'gap in ones knowledge' also includes 'gap in his/her/my/their/s knowledge'. Looking at the wikipedia and google entries it would seem that knowledge gap could be nearest to wissenskluft, with a gap in ones knowlege closer to wissenslüke.

5,800 for "gap in his knowledge
993 for "gap in her knowledge
12,400 for "gap in my knowledge
111,000 for "gap in our knowledge
910 for "gap in their knowledge
619 for "gap in your knowledge

= 131,722 Google hits for "gap in one's knowledge"

I don't support the deletion of "gap in one's knowledge" as it is more commonly used this way when talking about a gap in a person's knowledge, with "my" etc:

483 for "my knowledge gap
12,400 for "gap in my knowledge

But I support the addition of "knowledge gap" - one translation of this would seem to be "Wissenskluft", a gap between different people's knowledge:

"The knowledge gap hypothesis states that 'as the infusion of mass media information into a social system increases, segments of the population with higher socio-economic status tend to acquire this information at a faster rate than the lower status segments, so that the gap in knowledge between these segments tends to increase rather than decrease' (Tichenor et al. (1970) quoted in Kleinnijenhuis (1991))" http://www.cultsock.ndirect.co.uk/MUHome/csht...

"Die Hypothese der wachsenden Wissenskluft von Phillip Tichenor, George Donohue und Clarice Olien von der Minnesota-University im Jahr 1970 erstmals in der Zeitschrift Public Opinion Quarterly publiziert, besagt, dass Medien die ungleiche Verteilung von Wissen zwischen sozioökonomisch besser gestellten Bevölkerungsgruppen und Menschen mit niedrigem sozioökonomischen Status verschärfen." http://de.wikipedia.org/wiki/Wissenskluft

(I'm adding the language links at wikipedia if anyone wonders)