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Case Reports in Genetics
Volume 2011, Article ID 158086, 5 pages
Case Report

Inheritance of a Ring Chromosome 21 in a Couple Undergoing In Vitro Fertilization (IVF): A Case Report

1Diagnostic Genetics, LabPlus, Auckland City Hospital, P.O. Box 110031, Auckland 1148, New Zealand
2School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
3Northern Regional Genetic Service, Auckland City Hospital, Private Bag 92024, Auckland 1142, New Zealand

Received 28 April 2011; Accepted 24 May 2011

Academic Editors: P. D. Cotter, B. Mittal, and A. Sazci

Copyright © 2011 Roberto L. P. Mazzaschi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


An amniotic fluid sample from an in vitro fertilized pregnancy was referred for cytogenetic analysis based on a Down syndrome screening risk of 1 : 21. Routine cytogenetic analysis showed a nonmosaic karyotype of 46,XX,r(21)(p11.2q22.3), with partial monosomy for chromosome 21 due to a ring chromosome replacing one of the normal homologues. Detailed ultrasound scanning for the remainder of the pregnancy did not reveal any unusual findings. Parental bloods showed that the mother was mosaic for the ring 21 with a karyotype of 46,XX,r(21)(p11.2q22.3)/46,XX and the father had an unrelated Robertsonian translocation, with a karyotype of 45,XY,rob(13;14)(q10;q10). Microarray analysis of cultured amniocytes determined the extent of the deletion of chromosome 21 material in the ring. The parents were given genetic counselling, and a phenotypically normal female baby was delivered at term. This case highlights the importance of karyotyping as an initial step in the management of couples referred for in vitro fertilization.