Prenatal diagnosis of de novo small supernumerary marker chromosome 4q (4q11-q12): A case report.
Int J Reprod Biomed 2021;
19:477-482. [PMID:
34278202 PMCID:
PMC8261101 DOI:
10.18502/ijrm.v19i5.9258]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 09/06/2020] [Accepted: 10/06/2020] [Indexed: 11/28/2022] Open
Abstract
Background
Small supernumerary marker chromosomes (sSMCs) are chromosomal fragments with
abnormal structures found in patients with fertility problems and
developmental delay. They may be detected in amniotic cell karyotypes. sSMCs
are categorized as hereditary or de novo. Here, we describe a case of
prenatal de novo 4q11q12 sSMC and its molecular cytogenetic features which
had no apparent phenotypic abnormality.
Case
The fetus of a 36-yr-old pregnant woman was detected positive for Down's
syndrome (trisomy 21) at the 16 th wk of gestation. Quantitative fluorescent polymerase chain
reaction technique was applied for the rapid detection of numerical
aneuploidy of chromosomes X, Y, 13, 18, and 21 microsatellites. Array
comparative genomic hybridization (array CGH) technique was also conducted
following the karyotype analysis of amniotic cells. The karyotype analysis
was also done for the parents. Quantitative fluorescent polymerase chain
reaction result revealed a male fetus with a normal chromosomal pattern,
while the amniocentesis karyotype analysis identified a male fetus with a
marker chromosome (47, XY, +mar), and the sSMC were existing in 100% of
amniocyte metaphase spreads. The parents' normal karyotypes indicated that
the sSMC was de novo. Array CGH analysis revealed a 6.48-Mb duplication at
4q11q12. Eventually, the parents decided to terminate the pregnancy by legal
abortion.
Conclusion
Our study highlights the importance of the application of array CGH in
combination with karyotype analysis for rapid and precise prenatal diagnosis
of partial aneuploidy region.
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