Double aneuploidy mosaicism involving chromosomes 18 and 21 in a neonate

Christina Mendiola, Veronica Ortega, Allison Britt, Rafael Fonseca, Gopalrao Velagaleti

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Background: Double aneuploidy is common, especially in products of conception, frequently involving a combination of a sex chromosome and an acrocentric chromosome. Double autosomal trisomies are rare with only five cases reported. Double aneuploidy mosaicism involving two different cell lines is rarer with only three cases reported. Case presentation: We report a fourth case of double aneuploidy mosaicism on a baby. Results of a 24-h preliminary chromosome analysis at birth showed a mosaic karyotype, 47,XX,+18[15]/47,XX,+21[8]/48,XX,+21,+mar[7]. Reflex testing to SNP microarray with the same sample collected at birth showed gain of a 77.9 Mb region on chromosome 18 and gain of a 32.5 Mb region on chromosome 21. Microarray did not show any other copy number variants indicating that the marker chromosome may not contain any euchromatic material. A repeat chromosome analysis at 1-year of age showed a mosaic karyotype, 47,XX,+18[76]/47,XX,+21[4] with loss of the marker cell line. Conclusion: Based on our results, we propose that the mosaic double autosomal trisomy in our case was due to two independent non-disjunction events in a normal zygote very early during embryogenesis.

Original languageEnglish (US)
Article number1
JournalMolecular Cytogenetics
Issue number1
StatePublished - Dec 2022


  • Double aneuploidy
  • Non-disjunction
  • SNP microarray
  • Trisomy 18
  • Trisomy 21

ASJC Scopus subject areas

  • Genetics(clinical)
  • Biochemistry, medical
  • Genetics
  • Molecular Medicine
  • Molecular Biology
  • Biochemistry


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