Functional mapping of the human genome by cDNA localization versus sequencing

Two approaches are being applied in genome mapping that vary in the way gene sequences are analyzed. The first approach analyzes gene sequences made from copies of messenger RNA, while the second approach uses systematic sequencing of a DNA which is the compared to the cDNA. Sequences are marked with oligonucleotide primers to divide the parts being studied. Genome mapping is continually hindered by sequences containing a large amount of guanine and cytosine and the presence of repetitive sequences.