[Implementation of arrays in first trimester prenatal diagnosis]

Objective: Array technology in chorionic villus sampling (CVS) - analysis of clinical benefit and a proposal of a more effective 1st trimester genetic testing policy.

Design: Retrospective study.

Setting: Gennet, Center of Medical Genetics and Reproductive Medicine, Prague.

Material and methods: Total of 913 CVS were performed at Gennet between 2010-2014. All 913 samples were tested by QF-PCR rapid test for aneuploidy of chromosomes 13, 18, 21, X and Y and karyotyping following standard long term culture. Microarray analysis (Illumina HumanCytoSNP12 v2.1) was performed on 179 samples with normal result from both - QF-PCR and karyotyping.

Results: At 229 samples the common chromosomal aneuploidy was detected using rapid QF-PCR (25% from 911 successful rapid tests). Conventional karyotyping revealed 239 unbalanced chromosome aberrations (27% from 897 successful cultivations). 227/239 (95%) positive karyotypes confirmed QF-PCR finding of common aneuploidies. 10 unbalanced chromosome aberrations were not covered by rapid QF-PCR test. Microarray analysis of samples with normal result from both- QF-PCR and karyotyping- revealed 13 clinically relevant chromosome aberrations (7.5%).

Conclusion: New policy for chorionic villi testing at Gennet was established. Based on evaluation of the results of karyotyping, array and QF-PCR and analysis of published data we decided to replace karyotyping by microarray analysis in all cases of foetuses with normal results from QF-PCR. More effective detection of pathological and clinically relevant chromosome aberrations in examined foetuses is expected.