I have gene symbol list like following.
2-Sep
Hist2h4
5-Mar
Nupr1
7-Sep
5-Mar
15-Sep
11-Sep
Egam-1c
I have not ever seen "2-Sep" and "5-Mar" . These gene symbol are from where? you know?
Furthermore, do you know some ID conversion application able to change the above gene symbol to Ensemble ID.
Change the format on the column to "text" in excel and the transformation should get fixed. Then get that list out of Excel ASAP.
They are two different columns and you are viewing date and geneId columns together.
How to avoid conversion of gene symbols to date format in Excel