Hereditary Genetics: Current Research

Abstract

Antenatal Detection of Trisomy 21 from Mosaic Translocation in Uncultured Amniocytes by Interphasic FISH

Henriette Poaty, Dominique Carles and Laurence Taine

Introduction: We report a rare case of fetus having trisomy 21 from mosaic translocation. The purpose of this study was to present the interest of interphasic fluorescence in situ hybridization (FISH) performed on uncultured amniocytic cells in prenatal diagnosis of trisomy 21.

Patient and methods: From a pregnancy of 22 weeks old in 40 years old woman with a history of spontaneous miscarriage, chromosomal analysis (karyotype) has been done on trophoblast cells, in amniotic fluid cells, and combined with interphasic FISH performed on none cultured amniocytic cells associated to metaphasic FISH.

Results: Karyotype analysis revealed 46, XX, der (21; 21) (q10; q10), + 21 [17]/46, XX [3]. The trisomy 21 from mosaïc translocation was confirmed within 24 hours by interphasic nuclei from none cultured amniotic cells, then by metaphasic FISH.

Conclusion: The interphasic FISH analysis (in uncultured amniocytes) allows a quick and efficient prenatal diagnosis of aneuploidy, but it is a complementary analysis to other cytogenetic methods.