Mrs. NGUYỄN THỊ NGA - Director of CGAT
POLYMERASE CHAINREACTION AND DNA FINGERPRINTING
The idea to study and apply molecular genetics in Vietnam appeared in our mind since 1988, originating from Kary Mulis's discovery on Polymerase Chain Reaction (PCR), and when we could buy a thermocycler in Moscow (see photo) on the way back to Vietnam from the XVIth International Congress of Genetics held in Toronto, Canada (September,1988). The trip was sponsored by a Dutch Project named VH3.
Nowadays, PCR has became a routine technique in the laboratories of Molecular Biology all over the World. However, the most practical application of PCR is DNA testing. Recently in a meeting of world wide experts on technologies, 25 most advanced innovations, made during the passed 25 years has been chosen, having strong influence on the human life at present and in future. DNA testing was among them and it is unique in the field of Medicine and Biology (CNN source, January 2005).
APPLICATION OF DNA FINGERPRINTING IN VIETNAM
During the passed 20 years in the framework of different research topics we have obtained the results as follows:
- Over 2000 experiments were carried out.
- The allele frequencies of 40 polymorphic loci in Vietnamese were determined with 200-3000 samples for each allele. At the moment 10 other loci are under investigation for determination of their allelic frequencies.
- At present each relationship test reaches 99,999% accuracy as minimum.
- Up to now we have made paternity tests for over 7,000 families on volunteer's basis or for courts and embassies.
- We train many technicians for the national institutions of forensic profile.
- Nowadays our Center has close cooperation with several over-sea universities and research centers to meet the practical demands of Vietnam, as well as to improve the knowledge and skills for our staff.
DNA TYPING FOR SKELETAL REMAINS
At present there are 4 kinds of markers, which are used in DNA typing skeletal remains. These are markers on mtDNA, miniSTR, Y-STR and SNPs. The first one locates on mtDNA. The rest three kinds of markers relay on nuclear DNA. Each kind of markers has its own advantages and disadvantages. Depending on the level of a sample degradation one can choose suitable kind of markers. In cases the DNA degradation level is low one can choose the markers located on cell nuclei. The accuracy of the test will be higher. In cases the sample degradation level is high, the kind of markers should be chosen, is mtDNA. The accuracy is lower and the test time takes several weeks.
In Vietnam now all the labs are using mtDNA markers, except CGAT (Center for Genetic Analysis and Technologies), which applies both mtDNA and nuclear DNA for typing ancient samples.
Skeletal remains samples for typing may be a piece of bone (2-3g) or 1-2 teeth. The samples should be stored in dry and cool places before delivering to CGAT. Control samples are taken from maternal relatives of the remains in case of mtDNA typing. For nuclear DNA typing, control samples can be taken from brothers or children of the remains sample.
It takes 7 days for mtDNA typing and 5 days for nuclear DNA typing.