Embryology Research Today is a free monthly online journal that collates and summarizes the latest research about Embryology, including details on stem cells, reproduction, transplants, cloning.

Cytogenetic and histological features of a human embryo with homogeneous chromosome 8 trisomy.

Golzio C, Guirchoun J, Ozilou C, Thomas S, Goudefroye G, Morichon-Delvallez N, Vekemans M, Attié-Bitach T, Etchevers HC

INSERM U781, Hôpital Necker - Enfants Malades, 149 rue de Sèvres, 75743 Paris Cedex 15, France.

BACKGROUND: Homogeneous and complete trisomy 8 is extremely rare. With one recent neonatal exception, all reported cases have been mosaic, due to mitotic non-disjunction during early zygotic development. We report a case of chromosome 8 trisomy in a human embryo examined at Carnegie stage 11 (25 days post-fertilization). It presented severe cardiovascular and central nervous system malformations. METHODS: The unusual bifid heart in this embryo spurred a detailed histological examination, karyotyping of a chorionic villus sample and subsequent FISH on inter-phase nuclei of intra-embryonic sections. RESULTS: Trophoblast cells had a karyotype of 47,XX, +8. Within the embryo proper, FISH demonstrated that the trisomy 8 was homogeneous in embryonic as well as extra-embryonic tissues. FQ-PCR supports a meiosis I origin of non-disjunction. In sections, the pharyngeal arches (including cardiac outflow tract), forebrain, mesonephros and liver were absent. Somites and yolk sac blood vessels were irregularly shaped. CONCLUSION: We show that homogeneous, intra-embryonic trisomy 8 is compatible with implantation and early human development. Molecular pathways that may be compromised and their impact on organogenesis are discussed.

Published 7 December 2006 in Prenat Diagn, 26(13): 1201-5.
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