This function extends each region in a Genomic Ranges object by a designated upstream and downstream extension in a strand-aware fashion
extendGR(gr = NULL, upstream = NULL, downstream = NULL)A GRanges object.
The number of basepairs upstream (5') to extend each region in gr in a strand-aware fashion.
The number of basepairs downstream (3') to extend each region in gr in a strand-aware fashion.