Ring 22 duplication/deletion mosaicism: clinical, cytogenetic, and molecular characterisation
- Jill K Frizzleya,
- Mark J Stephanb,
- Allen N Lambc,
- Patricia P Jonasb,
- Roger M Hinsonb,
- Donald R Moffittb,
- Dana L Shkolnya,
- Heather E McDermida
- aDepartment of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9, bDepartment of Pediatrics, Madigan Army Medical Center, Tacoma, WA 98431, USA, cDivision of Cytogenetics, Genzyme Genetics, Sante Fe, NM 87505, USA
- Dr McDermid.
- Received 4 November 1997
- Revised 14 July 1998
Abstract
A patient with several features consistent with duplication of 22q11.2 (cat eye syndrome or CES) was found to be mosaic for a dicentric double ring chromosome 22 on postnatal karyotyping of peripheral blood. The initial karyotype was 46,XX,r(22)(p12q13) [46]/46,XX,dic r(22)(p12q13; p12q13)[4]. The amount of material duplicated in the dic r(22) was determined to include and extend beyond the CES critical region into 22q13.3. However, karyotyping of lymphocytes and fibroblasts, at 27 and 13 months of age respectively, showed no dic r(22) present in any of the cells examined. We suggest that the CES features in this patient, and potentially in other ring cases with CES phenotypic features, might result from a high level of mosaicism for a dic r(22) during early fetal development. Usually this unstable dic r(22) is subsequently lost from most cells.
