The question is regarding snRNA-seq data of the ROSMAP (465 individuals sequenced) The mapping file syn34572333 contains cell barcodes for each libraryBatch and the corresponding individuals IDs. I filtered this file to contain only entries from libraryBatch 200225-B10-A I also downloaded the processed files of the same libraryBatch 200225-B10-A from syn51121986 syn51121983 syn51121993 and I created a seurat object Now the issue is that when I tried to check if all the barcodes from the counts/ seurat object are present in the mapping file, I found that they are not present, so I cannot know to whom the barcodes in the counts belong to. The barcodes that intersect between mapping file cell barcodes column and serurat object/counts barcodes column are only 21654 and they diff in 47271 barcodes !! which makes finding the individuals IDs for the barcodes in the counts matrix impossible. (correct me if I am wrong please). For example, [1] "TCTGGCTGTTAGAAGT-1" "GGGCTACCAATATCCG-1" "CATTCCGAGTGCTACT-1" "CTTACCGGTGCTAGCC-1" "CCACCATTCCAGCCTT-1" "TAGGTACAGCCGTAAG-1" are among the barcodes present in the processed file counts/seurat object from libraryBatch 200225-B10-A but are not available in libraryBatch 200225-B10-A in the mapping files, so I cannot trace which individuals they belong to. I hope Dr @masashi can help. Thank you so much.