Preimplantation genetic diagnosis of X-linked diseases examined by indirect linkage analysis.

BACKGROUND: Many centers of assisted reproduction in the Czech Republic offer preimplantation genetic diagnosis with fluorescent in situ hybridization (FISH) to couples requiring preimplantation genetic diagnosis (PGD) of X-linked diseases. However, this process results in discarding all male embryos and is not able to distinguish a carrier or healthy female embryo in X-linked recessive disorders. OBJECTIVES: The main aim of this study was to summarize a six-year period of PGD of X-linked monogenic diseases using indirect linkage analysis. METHODS AND RESULTS: We wanted to accentuate the advantage indirect analysis of PGD using multiple displacement amplification (MDA) followed by short tandem repeat (STR) analysis. We present forty-six PGD cycles, including pre-case haplotyping (PGH) panel, for fifteen X-linked diseases. Embryo transfer was made thirty-eight times and gravidity was confirmed in thirteen female probands with a success rate of pregnancy calculated at 42 %. CONCLUSIONS: PGD procedure using MDA amplification followed by STR analysis provides help in identifying genetic defects within embryos prior to implantation. The reliability of the method was also supported by high pregnancy rate compared to other publications, which commonly achieved a 30-35 % success rate (Tab. 2, Fig. 1, Ref. 33).

[Implementation of arrays in first trimester prenatal diagnosis]. / Implementace array vysetrení do prenatální diagnostiky v I. trimestru.

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.