hg19 and GRCh37: what they are, how they differ, and when to still use them
hg19 is UCSC's packaging of the GRCh37 human reference assembly. They are nearly the same sequence with different chromosome names and a different mitochondrion, and the coordinates do not match GRCh38. Here is how to tell which build your files use and how to move between them without corrupting your data.