title: Recombinants of intrachromosomal transposition of subtelomeres in chromosomes 1 and 2: a cause of minute terminal chromosomal imbalances.
abstract: Two cases of submicroscopic recombinants of intrachromosomal transposition of telomeres, one each from chromosome 1 and 2 are described. Meiotic crossing-over would generate the recombinants from these reciprocal rearrangements. In both cases, which were detected by FISH with subtelomeric probes, there is a minute deletion of the qter region and a second presence of the pter subtelomeric region on the respective qter, i.e., a duplication of 1pter or 2pter respectively. The deletion on 2qter (case 2) was confirmed by microsatellite inheritance and was of paternal origin, but in case 1 there was no detectable 1q deletion other than of the subtelomeric probe, and parental origin could not be determined. The present case 2 with del(2qter)/dup(2pter) shares many features with reported cases of simple deletion (2qter) but did not have features of Albright hereditary osteodystrophy, which are seen in half of such deletion patients. The clinical features present in case 1 were similar to those of the previously reported case of a submicroscopic 1qter deletion but also to cases with microscopically visible 1qter deletions, presumably because of gene enrichment in subtelomeric regions. Recombinants of such intrachromosomal subtelomere transpositions detected by subtelomeric probes may comprise up to 10% of submicroscopic pter or qter deletion cases. Other cases of this unusual mechanism may be detected with more common use of subtelomeric probes. It is suggested the bouquet associations of telomeres in early meiosis may facilitate such unusual rearrangements.
authors.affiliation: Cytogenetics Department, Western Sydney Genetics Program, The Children's Hospital at Westmead, Sydney, Australia. artd@chw.edu.au
authors.forename: Art
authors.initials: A
authors.lastname: Daniel
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Baker
authors.forename: Nicole
authors.initials: N
authors.lastname: Chia
authors.forename: Eric
authors.initials: E
authors.lastname: Haan
authors.forename: Paul
authors.initials: P
authors.lastname: Malafiej
authors.forename: Lyn
authors.initials: L
authors.lastname: Hinton
authors.forename: Nigel
authors.initials: N
authors.lastname: Clarke
authors.forename: Lesley
authors.initials: L
authors.lastname: Adès
authors.forename: Artur
authors.initials: A
authors.lastname: Darmanian
authors.forename: David
authors.initials: D
authors.lastname: Callen
mesh_terms: D000293:Adolescent; D002648:Child; D002869:Chromosome Aberrations; D002871:Chromosome Banding; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D002889:Chromosomes, Human, Pair 2 / Q000235:genetics*; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D010641:Phenotype; D016615:Telomere / Q000235:genetics*; D014178:Translocation, Genetic