Mosaic complete tetrasomy 21 in a fetus with complete atrioventricular septal defect and minor morphological variations

ConclusionOur observation and the review of the literature reported the possibility of very weak mosaicism and disease ‐causing confined tissue‐specific mosaicism in fetus or alive patients with chromosome 21 aneuploidy, mainly Down syndrome. In case of clinical diagnosis suggestive of Down syndrome, attention must be paid to the risk of false‐negative test due to chromosomal mosaicism (very weak percentage, d ifferent tissue distribution). To overcome this risk, it is necessary to privilege the diagnostic techniques without culture step and to increase the number of cells and tissues analyzed, if possible. This study highlights the limits of microarray as the unique diagnostic approach in case of weak mo saic and French cytogenetics guidelines recommend to check anomalies seen in microarray by another technique on the same tissue.

Source: Molecular Genetics & Genomic Medicine - September 6, 2019 Category: Genetics & Stem Cells Authors: Vincent Gatinois, Nicole Bigi, Eve Mousty, Jean Chiesa, Yuri Musizzano, Anouck Schneider, Genevi ève Lefort, Lucile Pinson, Jean‐Baptiste Gaillard, Clémence Ragon, Marie‐Josée Perez, Magali Tournaire, Patricia Blanchet, Carole Corsini, Tags: ORIGINAL ARTICLE Source Type: research