title: Expansion in size of a terminal deletion: a paradigm shift for parental follow-up studies.
abstract: BACKGROUND
  Parental studies are often necessary subsequent to the identification of a chromosome abnormality. The recommended studies are based on assumptions about how chromosome rearrangements occur. One such assumption is that deletion size is stable through generations.
  
  
  RESULTS
  We have identified a family where a small subtelomeric deletion in a phenotypically and cytogenetically normal mother expanded nearly 10-fold into a clinically consequential and cytogenetically visible deletion in her affected daughter.
  
  
  CONCLUSIONS
  Traditional parental follow-up studies would have not identified this expansion, but would have rather classified the deletion in the daughter as either de novo or benign. Only by sizing the deletion by array comparative genomic hybridisation in both the mother and the daughter was the expansion recognised. Previous assumptions about chromosome behaviour suggest that this phenomenon may have been easily missed in other cases of chromosomal deletions. Therefore, this case illustrates the need for more comprehensive analyses of parental chromosome structure when characterising an abnormality in a child.
authors.forename: S T
authors.initials: ST
authors.lastname: South
authors.forename: A F
authors.initials: AF
authors.lastname: Rope
authors.forename: A N
authors.initials: AN
authors.lastname: Lamb
authors.forename: E
authors.initials: E
authors.lastname: Aston
authors.forename: N
authors.initials: N
authors.lastname: Glaus
authors.forename: H
authors.initials: H
authors.lastname: Whitby
authors.forename: T
authors.initials: T
authors.lastname: Maxwell
authors.forename: X L
authors.initials: XL
authors.lastname: Zhu
authors.forename: A R
authors.initials: AR
authors.lastname: Brothman
mesh_terms: D002887:Chromosomes, Human, Pair 18; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D009693:Nucleic Acid Hybridization; D010290:Parents; D010375:Pedigree; D017384:Sequence Deletion