Polymerase Chain Reaction Gap PCR Kho SL, Chua KH, George E, Tan JA. A novel gap-PCR with high resolution melting analysis for the detection of α-thalassaemia Southeast Asian and Filipino β°-thalassaemia deletion. Sci Rep. 2015;5:13937. Published 2015 Sep 14. doi:10.1038/srep13937 None Request inclusion into relevant ontology. The polymerase chain reaction (PCR) is the most common method to detect the deletional thalassaemias. Gap-PCR amplifies the deleted DNA sequence using the primers flanking the deleted region 10. Three primers are designed for each deletion to amplify the normal (undeleted) and deleted gene sequences.