Recurring germline mosaicism in a family due to reversion of an inherited derivative chromosome 8 from an 8;21 translocation with interstitial telomeric sequences

Weimin Bi, Bo Yuan, Pengfei Liu, Jaclyn B. Murry, Xiang Qin, Fan Xia, Thao Quach, Lance M. Cooper, Joanna Wiszniewska, Patricia Hixson, Sandra Peacock, Vijay S. Tonk, Robert W. Huff, Veronica Ortega, James R. Lupski, Steven E. Scherer, Rebecca Okashah Littlejohn, Gopalrao V.N. Velagaleti, Elizabeth R. Roeder, Sau Wai Cheung

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Mosaicism for chromosomal structural abnormalities, other than marker or ring chromosomes, is rarely inherited. Methods: We performed cytogenetics studies and breakpoint analyses on a family with transmission of mosaicism for a derivative chromosome 8 (der(8)), resulting from an unbalanced translocation between the long arms of chromosomes 8 and 21 over three generations. Results: The proband and his maternal half-sister had mosaicism for a der(8) cell line leading to trisomy of the distal 21q, and both had Down syndrome phenotypic features. Mosaicism for a cell line with the der(8) and a normal cell line was also detected in a maternal half-cousin. The der(8) was inherited from the maternal grandmother who had four abnormal cell lines containing the der(8), in addition to a normal cell line. One maternal half-aunt had the der(8) and an isodicentric chromosome 21 (idic(21)). Sequencing studies revealed microhomologies at the junctures of the der(8) and idic(21) in the half-aunt, suggesting a replicative mechanism in the rearrangement formation. Furthermore, interstitial telomeric sequences (ITS) were identified in the juncture between chromosomes 8 and 21 in the der(8). Conclusion: Mosaicism in the proband, his half-sister and half-cousin resulting from loss of chromosome 21 material from the der(8) appears to be a postzygotic event due to the genomic instability of ITS and associated with selective growth advantage of normal cells. The reversion of the inherited der(8) to a normal chromosome 8 in this family resembles revertant mosaicism of point mutations. We propose that ITS could mediate recurring revertant mosaicism for some constitutional chromosomal structural abnormalities.

Original languageEnglish (US)
Article number108586
JournalJournal of medical genetics
DOIs
StateAccepted/In press - 2022

Keywords

  • Chromosome Aberrations
  • Cytogenetics
  • Genetic Phenomena
  • Genomic Instability
  • Human Genetics

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

Fingerprint

Dive into the research topics of 'Recurring germline mosaicism in a family due to reversion of an inherited derivative chromosome 8 from an 8;21 translocation with interstitial telomeric sequences'. Together they form a unique fingerprint.

Cite this