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Application of Multiple Short Tandem Repeat Loci for Rapid Diagnosis of Down Syndrome and Edward Syndrome by Kangying Wang, Li Lai, Haijian Tu, Hua Lin, Xiaoli Shen

Background: Chromosomal diseases with chromosomal abnormalities are one of the most common genetic diseases in humans, including abnormal numbers and structural abnormalities. Patau syndrome (also known as trisomy 13), Edward syndrome (also called trisomy 18), and Down syndrome (also known as trisomy 21) are all clinically fatal diseases caused by abnormal numbers of autosomes. However, there is no reliable and effective cure for chromosomal diseases, mainly relying on fast and accurate prenatal diagnosis technology to reduce the rate of birth defects.
Methods: Fluorescent-labeled primers were designed and then used in fluorescence quantitative polymerase chain reaction (FQ-PCR) composite amplification, capillary electrophoresis typing, and gene fragment analysis technology to detect 64 amniotic fluid samples, which were indicated high risks of trisomy 18 and 21 by non-invasive prenatal diagnostic technology (NIPT). The results are compared with the results of karyotype analysis and chromo-some copy variations (CNVs).
Results: Sixty-four samples were determined by FQ-PCR technology with the help of short tandem repeat (STR) regarded as molecular marker (STR-FQ-PCR), the result showed 61 cases of chromosomal aneuploidy were positive, including 14 cases of Edward syndrome and 47 cases of Down syndrome. A total of 460 STR locus genotypes were detected, containing 84 STR locus genotypes of Edward syndrome and 376 STR locus genotypes of Down syndrome. Chromosome karyotype analysis showed that the detected samples were all chromosomal aneuploidy. Among them were 15 cases of trisomy 18, including 14 cases of homozygous type and 1 case of chimeric type, 49 cases of trisomy 21, consisting of 47 cases homozygous type and 2 cases chimeric type. Sixty-two cases of chromosomal aneuploidy were detected by CNVs with 14 cases of trisomy 18 and 48 cases of trisomy 21.
Conclusions: The detectable rate of STR-FQ-PCR technology is 95.31% while the karyotype analysis is the highest with 100%. For non-chimera and non-structural abnormal samples, the coincidence rate of results between STR-FQ-PCR technology and karyotype analysis was 100%. All above manifested the application of multiple STR loci for rapid diagnosis of Down syndrome and Edward syndrome has high clinical value.

DOI: 10.7754/Clin.Lab.2020.201112