Investigation of two cases of paternal disomy 13 suggests timing of isochromosome formation and mechanisms leading to uniparental disomy

Sue Ann Berend, Gerald L. Feldman, Christopher McCaskill, Paula Czarnecki, Daniel L. Van Dyke, Lisa G. Shaffer

Research output: Contribution to journalArticle

34 Scopus citations

Abstract

Uniparental disomy (UPD) is the abnormal inheritance of two copies of a chromosome from the same parent. Possible mechanisms for UPD include trisomy rescue, monosomy rescue, gametic complementation, and somatic recombination. Most of these mechanisms can involve rearranged chromosomes, particularly isochromosomes and Robertsonian translocations. Both maternal and paternal UPD have been reported for most of the acrocentric chromosomes. However, only UPD for chromosomes 14 and 15 show an apparent imprinting effect. Herein, we present two cases of paternal UPD 13 involving isochromosomes. Both cases were referred for UPD studies due to the formation of a de novo rea(13q13q). Case 2 was complicated by the segregation of a familial rob(13q14q) of maternal origin. Both propositi were phenotypically normal at the time of examination. Polymorphic marker analysis in Case 1 showed the distribution of alleles of markers along chromosome 13 to be complete isodisomy, consistent with an isochromosome. This rearrangement could have occurred either meiotically, without recombination, or mitotically. A likely mechanism for UPD in this case is monosomy rescue, through postzygotic formation of the isochromosome. In Case 2 the distribution of proximal alleles indicated an isochromosome, but recombination was evident. Thus, this isochromosome must have formed prior to or during meiosis I. A likely mechanism for UPD in this case is gametic complementation, since the mother carries a rob(13q14q) and is at risk of producing aneuploid gametes. However, trisomy rescue of a trisomy 13 conceptus cannot be completely excluded. Given that both cases were phenotypically normal, these data further support that paternal UPD 13 does not have an adverse phenotypic outcome and, thus, does not show an apparent imprinting effect.

Original languageEnglish (US)
Pages (from-to)275-281
Number of pages7
JournalAmerican journal of medical genetics
Volume82
Issue number3
DOIs
StatePublished - Jan 29 1999

Keywords

  • Chromosomal rearrangement
  • Cytogenetics
  • Imprinting
  • Isochromosome
  • Parental origin
  • Uniparental disomy

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

Fingerprint Dive into the research topics of 'Investigation of two cases of paternal disomy 13 suggests timing of isochromosome formation and mechanisms leading to uniparental disomy'. Together they form a unique fingerprint.

  • Cite this