Off topic:Removing text after pattern using sed

Question

[T_18]

Dear all,

I am just new in the world of sed.. Simple question, but struggling now for quit a while with this:

I have a list of gene names:

CYP6k1
CYP4L15
CYP354A5
CYP4d8
CYP354A5
CYP354A14
CYP4c1
CYP354A5
CYP4V2
CYP354A5

I only want to keep "CYP" and the number, so: CYP6, CYP4 etc. I tried to use sed as follows (closest I could get):

sed -E 's/[A-Z]{3}[0-9]+//'

But this is removing exactly the bit that I want to keep and I cannot use 'verbose' in combinaton with sed.

Any help is much appreciated! Thanks!