Fetal free DNA ABO genotyping Kit(PCR-Taqman)
SUPER021-001CF-024
The kit is used for the detection of ABO blood group genotype of free DNA in peripheral blood fetuses of type O pregnant women, including alleles A, B, O, and can assist in the diagnosis of fetal hemolytic disease caused by maternal fetal ABO blood group incompatibility. This kit cannot be used for blood source screening.

Hemolytic disease of the fetus and newborn (HDFN) is mainly characterized by maternal fetal ABO blood group incompatibility in China. According to literature reports, out of 5669 cases of maternal infant blood group incompatibility, 1465 cases (25.8%) were diagnosed with HDFN, of which ABO related HDFN accounted for 98.09% ^[2]. At present, there are multiple interfering factors in the detection of IgG in pregnant women, so there are certain limitations in early diagnosis of HDFN based only on serology in clinical ^[2], Therefore, the identification of blood type genes in HDFN is particularly important in clinical diagnosis and blood transfusion. With the further elucidation of the molecular basis of blood type genes, it is possible to detect fetal blood types at the DNA level. By detecting free DNA in the peripheral blood of pregnant women, non-invasive prenatal detection of ABO blood type in the fetus of type O pregnant women can be carried out. The results could provide reference for clinical diagnosis.

The design of this kit combines three PCR methods: TaqMan, nested PCR, and multiplex PCR. The specific primers are designed in a nested method, with the first pair of specific primers amplifying similar to regular PCR, while the second pair of specific primers are combined inside the first PCR product to further enhance amplification and control specificity, achieving a dual specific amplification reaction. And then, design and synthesize a probe based on the sequence of ABO gene from NCBI database that can specifically hybridize with it. The probe is labeled with a fluorescent group at the 5 'end and a quenched group at the 3' end. The spatial distance between the two groups is very close. Normally, the fluorescent group cannot emit fluorescence due to the quenched group. During PCR amplification, the primer and the probe are simultaneously bound to the template, with the probe binding position located between the upstream and downstream primers. When the amplification extends to the probe binding position, the 5 'exonuclease activity of Taq enzyme will cut off the fluorescent molecules connected to the 5' end of the probe from the probe, causing it to emit fluorescence. The number of detected fluorescent molecules is directly proportional to the number of PCR products. Determine the negativity and positivity based on the fluorescence intensity Ct value in the PCR reaction system. This reagent kit is designed with both internal standard primers and probes, which are coated together with specific primers and probes. If their results meet the quality control requirements of the experiment, the overall test judgment is valid.