title: Prenatal diagnosis of mosaic tetrasomy 21q confirmed by fluorescence in situ hybridization.
abstract: We describe the first case of a live-born neonate with mosaic tetrasomy 21q confirmed by fluorescence in situ hybridization (FISH). A 38-year-old Caucasian female presented for amniocentesis for maternal age. Initial chromosome analysis of the amniocytes using GTG-banding showed a mos47,XY, +?i(12p)/46,XY karyotype. Follow-up studies with FISH identified the isochromosome as an i(21q); mos47,XY, +i(21q)/46,XY. The patient was delivered at 38+ weeks gestation and umbilical cord blood samples were obtained. Chromosome analysis of 43 cord blood lymphocytes demonstrated a 46,XY karyotype in all cells. However, peripheral lymphocytes taken 1 day after birth showed 1 out of 120 lymphocytes to have an extra chromosome determined to be an i(21q). While initial clinical exam of the neonate revealed similarities to Down syndrome, long-term follow up of our patient will be required to provide the first definitive description of the mosaic tetrasomy 21 syndrome.
authors.affiliation: The Mount Sinai School of Medicine, The Mount Sinai Medical Center, New York, NY 10029, USA. nn@doc.mssm.edu
authors.forename: N P
authors.initials: NP
authors.lastname: Nagarsheth
authors.forename: H
authors.initials: H
authors.lastname: Mootabar
mesh_terms: D002869:Chromosome Aberrations; D025063:Chromosome Disorders; D002891:Chromosomes, Human, Pair 21; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007231:Infant, Newborn; D011296:Prenatal Diagnosis