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The meaning of chromosome mosaicism in chorionic villus sampling: A review
Ísida de Campos SouzaI,II; Thomaz Rafael GollopI
IInstituto de Medicina Fetal e Genética Humana, Rua Félix de Souza, 321, 04612-080 São Paulo, SP, Brasil. Send correspondence to I.C.S. Tel. (011) 530.0809, Fax (011) 535.4320, E-mail: isouza@spider.usp.br.
IIDepartamento de Biologia/Genética, Instituto de Biociências da Universidade de São Paulo, USP, São Paulo, SP, Brasil.
ABSTRACT
In the field of prenatal cytogenetic diagnosis the study of chromosomal mosaicism has attracted special attention. It is found in 1-2% of viable pregnancies and can be classified into one of three different types: confined to either cytotrophoblast or chorionic stroma, or affecting both. In this paper we review the embryological origin of chorionic villus to clarify the etiology of mosaicism, the role of mosaicism in chorionic villus sampling involving the main viable and unviable aneuploidies, chromosomal rearrangements and marker chromosomes, the importance of uniparental disomy, genomic imprinting and the effects of these factors on the course of pregnancy.
Keywords: chromosome mosaicism; chorionic villus.
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