title: An unusual chromosome 22q11 deletion associated with an apparent complementary ring chromosome in a phenotypically normal woman.
abstract: We report an unusual chromosome 22q11 deletion associated with an apparent complementary ring chromosome in a phenotypically normal woman with a family medical history of 22q11 deletion. Using peripheral blood samples, conventional karyotyping, Fluorescence In Situ Hybridization (FISH) analysis on metaphase spreads and oligo array-based comparative genomic hybridization (oligo array-CGH) were performed. After conventional cytogenetic examination, the chromosome formula was as follows: 47,XX,+r(?)[16]/46,XX[6]. The FISH analysis revealed that this patient had a rearranged chromosome 22 with decreased centromeric fluorescence intensity and deletion of the 22q11.2 locus. She also had a supernumerary ring chromosome composed of an alpha-satellite centromere of 22 origin and 22q11.2 locus. The oligo array-CGH profile showed a deletion of approximately 4.18 Mb on chromosome 22 with a log 2 intensity ratio mean deviation of the deleted region of about -0.29. The 22q11 deletion associated with a complementary ring chromosome described in our patient could be consistent with a centromere misdivision mechanism, with one chromosomal break occurring in the alpha-satellite array and a second one in the 22q11 locus, a mechanism which has recently been referred to as the McClintock mechanism.
authors.affiliation: Laboratoire de Cytogénétique, Service de Génétique Médicale, Hôpital Pellegrin (Maternité), CHU de Bordeaux, France. jerome.toutain@chu-bordeaux.fr
authors.forename: Jérôme
authors.initials: J
authors.lastname: Toutain
authors.forename: Laurence
authors.initials: L
authors.lastname: Taine
authors.forename: Fanny
authors.initials: F
authors.lastname: Morice-Picard
authors.forename: Houria
authors.initials: H
authors.lastname: Hallal
authors.forename: Zong-Qi
authors.initials: ZQ
authors.lastname: Dai
authors.forename: Benoît
authors.initials: B
authors.lastname: Arveiler
authors.forename: Didier
authors.initials: D
authors.lastname: Lacombe
authors.forename: Jacques
authors.initials: J
authors.lastname: Horovitz
authors.forename: Robert
authors.initials: R
authors.lastname: Saura
mesh_terms: D000328:Adult; D002872:Chromosome Deletion; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics*; D055028:Comparative Genomic Hybridization; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D010641:Phenotype; D012303:Ring Chromosomes