MGI batch query can be used on gene sets to be sure that all symbols are current nomenclature.
Here's how to do this:
1. go to MGI batch query
2. copy-paste your gene list into the tool
3. select "All symbols" for the Type
4. select Excel for the Output Type.
5. check the Genome Location box
6. click Search
7. open the Excel result and see column D
8. Copy-paste column D to your destination.