I am working on a promoter sequence of a gene to find SNPs for my project, for that, I gave sanger sequencing for some samples and I found one variation in my samples. How can I check this promoter variation is novel or not
so many ways to answer your question, the best for you for this topic and future plans would be to go to the UCSC website (http://genome.ucsc.edu), choose the genome browser tool with your species and position of the variant and see in the extra database if it's already exists.
if you don't have the genomic position, blast a part from your sequence containing the variant and you'll find the position.