Hi Wei,
My understanding of the blacklist is that it is used to filter out recurrent mutation sites that the MutSig development team found to cause issues with the determination of significance. Because these by nature include germline mutations that may not have been part of available databases at the original generation of the MAF, we are not permitted to release it to the public.
I will forward your question along to the developers to see if they can lend any more clarity.
Regards,
David
--
David Heiman
Run Operations Engineer
TCGA Genome Data Analysis Center
The Broad Institute of MIT and Harvard
415 Main Street
Cambridge, MA 02142