Chimerism for 20q11.2 microdeletion of GDF5 explains discordant phenotypes in monochorionic-diamniotic twins

Matthew M. Meredith, Beau Crabb, Marcelo Vargas, Betsy A. Hirsch

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Microdeletions of 20q11.2 are rare but have been associated with characteristic clinical findings. A 1.6 Mb minimal critical region has been identified that includes three OMIM genes: GDF5, EPB41L1, and SAMHD. Here we describe a male monozygotic, monochorionic-diamniotic twin pair with discordant phenotypes, one with multiple findings that overlap with those reported in 20q11.2 deletions, and the other unaffected. Microarray analysis revealed mosaicism for a 363 Kb deletion encompassing GDF5 in the peripheral blood of both twins, which was confirmed by FISH. Subsequent FISH on buccal cells identified the deletion only in the affected twin. The blood FISH findings were interpreted as representing chimerism resulting from anastomosis and the blood exchange between the twins in utero. The implications of this finding are discussed, as is the contribution of GDF5 to the associated clinical findings of 20q11.2 deletions.

Original languageEnglish (US)
Pages (from-to)3182-3188
Number of pages7
JournalAmerican Journal of Medical Genetics, Part A
Volume173
Issue number12
DOIs
StatePublished - Dec 2017

Keywords

  • 20q11.2
  • GDF5
  • buccal
  • chimerism
  • deletion
  • mosaicism
  • twins

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