Hi all, I'm new here, so sorry if this is a bit of an obvious question. I've been using blast for a while now, but am still learning. Here's my problem: I used formatdb to make a blast database from a text file with about 2000 genes. Everything went well, and I could query the database. But when I input a sequence from the original text file, the result isn't always 100%. Sometimes it comes out 98% or 95%, when it should always be 100%. When I look at the results, I find one or more series of xs, signifying a missing part of data. For example: Score = 1815 bits (4702), Expect = 0.0 Identities = 913/953 (95%), Positives = 913/953 (95%) LTLDRLSNTLSGGESQRISLATQXXXXXXXXXXXXDEPSIGLHQ (Query) LTLDRLSNTLSGGESQRISLATQ DEPSIGLHQ LTLDRLSNTLSGGESQRISLATQLGSSLVGSLYVLDEPSIGLHQ (Subject) Is there a way to make this 100%. I want to run the 2000 genes against another genome to find 100% similar regions, 95% similar regions and so on. Thanks Phil P