Proliferating cell nuclear antigen originally identified as an antigen that is expressed in the nuclei of cells during the DNA synthesis phase of the cell cycle. Part of the protein was sequenced and that sequence was used to allow isolation of a cDNA clone. PCNA helps hold DNA polymerase epsilon (Pol ε) to DNA. PCNA is clamped to DNA through the action of replication factor C (RFC), which is a heteropentameric member of the AAA+ class of ATPases. Expression of PCNA is under the control of E2F transcription factor-containing complexes. Since DNA polymerase epsilon is involved in resynthesis of excised damaged DNA strands during
Cell-free fetal DNA the fetal DNA is based on physical length of DNA fragments. Smaller fragments can represent up to seventy percent of the total cell free DNA in the maternal blood sample. In real-time PCR, fluorescent probes are used to monitor the accumulation of amplicons. The reporter fluorescent signal is proportional to the number of amplicons generated. The most appropriate real time PCR protocol is designed according to the particular mutation or genotype to be detected. Point mutations are analysed with qualitative real time PCR with the use of allele specific probes. insertions and deletions are analyzed by dosage measurements using quantitative