I have some queries. I would like to ask you all , if I can make the variant calls using HC or UG walker of GATK without a dbSNP file or not? Is that a possibility? Can we do that? I want to actually just make the calls for each of my normal , tumor and IPS samples the variants and then find the mutations exclusive to my tumor and IPS samples. In that am not so keen to find the novel mutations. So can I do the variant calling with UG or HC without dbSNP ? Please give me your suggestions if you anyone have performed this or not? If I donot put the dbSNP file ,what other impact will be there downstream apart from not being able to distinguish which are novel or known variants? Is there any other impact. I would appreciate any suggestions.