I downloaded the exon coordinates of the human genome (hg38) and ensembl version 87 from the biomart (http://dec2016.archive.ensembl.org/biomart). I extracted following information.
Chromosome/scaffold name Exon ID Exon Chr Start (bp) Exon Chr End (bp) Strand
for the same chromosome name and exon start and end coordinates, there are multiple Exon IDs. I am unable to understand why?
For example, on chromosome 5 positive strand (+), at the genomic coordinates (start position 141505393 and stop position 141505481), there are more than 1 exon IDs (ENSE00003461101 and ENSE00003463136 and ENSE00003473630 and ENSE3474096 and ENSE00003484284). In other words, all these different exon IDs are exactly the same exons with same start and stop coordinates on the same chromosome and on the same strand. How is that possible? Am I missing something?