genome GRCh38 twoBitPath GRCh38/GRCh38.2bit trackDb GRCh38/trackDb.txt groups groups.txt htmlPath GRCh38/description.html description GRCh38 organism GRCh38 orderKey 4800 scientificName GRCh38 defaultPos chr1:1-1000 genome hm twoBitPath hm/hm.2bit trackDb hm/trackDb.txt groups groups.txt htmlPath hm/description.html description hm organism hm orderKey 4800 scientificName hm defaultPos hmrefChr29899:1-1000 genome mm10 twoBitPath mm10/mm10.2bit trackDb mm10/trackDb.txt groups groups.txt htmlPath mm10/description.html description mm10 organism mm10 orderKey 4800 scientificName mm10 defaultPos chr1:1-1000