Thank you, that seems to work but I seem to have a problem with duplicates, which is causing errors in any downstream analysis or data wrangling. Please see the example below
GAK ENST00000511980 S1 2
GAK ENST00000511345 S1 1
ZNF517 ENST00000526178 S2 1
PTPN13 ENST00000427191 S3 1
IL15RA ENST00000379977 S4 1
Appreciating your suggestions in advance!