Background: We have investigated whether replacing conventional karyotyping by SNP array analysis in cases of foetal ultrasound abnormalities would increase the diagnostic yield and speed of prenatal diagnosis in clinical practice. Findings/results. From May 2009 till June 2011 we performed HumanCytoSNP-12 array (HCS) (http://www.Illumina.com) analysis in 207 cases of foetal structural abnormalities. HCS allows detecting unbalanced genomic abnormalities with a resolution of about 150/200 kb. All cases were selected by a clinical geneticist after excluding the most common aneuploidies by RAD (rapid aneuploidy detection). Pre-test genetic counselling was offered in all cases. In 24/207 (11,6%) foetuses a clinically relevant genetic abnormality was detected. Only 8/24 abnormalities would have been detected if only routine karyotyping was performed. Submicroscopic abnormalities were found in 16/207 (7,7%) cases. The array results were achieved within 1-2 weeks after amniocentesis. Conclusions: Prenatal SNP array testing is faster than karyotyping and allows detecting much smaller aberrations (∼0.15 Mb) in addition to the microscopic unbalanced chromosome abnormalities detectable with karyotyping (∼ > 5 Mb). Since karyotyping would have missed 66% (16/24) of genomic abnormalities in our cohort, we propose to perform genomic high resolution array testing assisted by pre-test counselling as a primary prenatal diagnostic test in cases of foetal ultrasound abnormalities.

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doi.org/10.1186/1755-8166-5-14, hdl.handle.net/1765/73076
Molecular Cytogenetics
Department of Gynaecology & Obstetrics

Srebniak, M., Boter, M., Oudesluijs, G., Cohen-Overbeek, T., Govaerts, L., Diderich, K., … Galjaard, R.-J. (2012). Genomic SNP array as a gold standard for prenatal diagnosis of foetal ultrasound abnormalities. Molecular Cytogenetics, 5(1). doi:10.1186/1755-8166-5-14