Prenatal diagnosis of mosaic tetrasomy 18p.

Abstract

OBJECTIVE:

To present prenatal diagnosis and molecular cytogenetic characterization of a small supernumerary marker chromosome derived from isochromosome 18p, by interphase fluorescence in situ hybridization (FISH) on uncultured amniocytes.

CASE REPORT:

A 41-year-old woman underwent amniocentesis at 18 weeks of gestation, because of advanced maternal age. Amniocentesis revealed a de novo supernumerary isochromosome 18p in two of 14 colonies of cultured amniocytes. Repeated amniocentesis was performed at 22 weeks of gestation. Interphase FISH analysis on uncultured amniocytes showed four 18p11.32-specific probe (RP11-324G2) signals in 5.7% (3/53 cells) of uncultured amniocytes. A multiplex ligation-dependent probe amplification P095 test kit and array comparative genomic hybridization analysis did not detect genomic imbalance in chromosome 18. Cytogenetic analysis of cultured amniocytes at repeated amniocentesis revealed a karyotype of 47,XY,+i(18)(p10)[3]/46,XY[23]. The pregnancy was carried to 38 weeks of gestation, and a healthy 3120 g male baby was delivered. When examined at 2 months of age, the infant was normal in growth and development, without phenotypic abnormalities. The cord blood had a karyotype of 46,XY. Polymorphic DNA marker analysis excluded uniparental disomy 18. Interphase FISH analysis on uncultured urinary cells showed 9.4% (3/32 cells) mosaicism for tetrasomy 18p.

CONCLUSION:

There is cytogenetic discrepancy between amniocytes and cord blood lymphocytes in prenatally detected mosaic tetrasomy 18p. Interphase FISH on uncultured amniocytes has the advantage of rapid confirmation of low-level mosaicism for tetrasomy 18p at amniocentesis.

• Authors: Chih-Ping Chen, Tsang-Ming Ko, Yi-Ning Su, Schu-Rern Chern, Jun-Wei Su, Yu-Ting Chen, Dai-Dyi Town, Wayseen Wang
• Journal: Taiwanese journal of obstetrics & gynecology (Taiwan J Obstet Gynecol) Vol. 51 Issue 4 Pg. 625-9 (Dec 2012) ISSN: 1875-6263 [Electronic] China (Republic : 1949- )
• PMID: 23276569 (Publication Type: Case Reports, Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2012. Published by Elsevier B.V.

Topics

• Adult
• Amniocentesis
• Chromosomes, Human, Pair 18 (genetics)
• Female
• Fetal Blood
• Humans
• Infant, Newborn
• Karyotyping
• Live Birth (genetics)
• Male
• Mosaicism
• Phenotype
• Pregnancy
• Prenatal Diagnosis
• Trisomy (diagnosis, genetics)