Calculating GQ for VCF file

Question

[Tsin-Lau]

Hello everyone in this community, I need help while processing VCF files. I want to do some quality control based on GQ (i.e. genotype quality), but this INFO is lacked in my VCF files with only the GL field (e.g. -5,0,-2.62903). Is there any tool to help calculating the GQ information?

Could anybody give me some advice? Furthermore, any other recommendation during my quality control step such as suggested threshold for each INFO?

Thank you very much!