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Ring chromosome 20 with loss of telomeric sequences detected by multicolour PRINS |
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| Authors: | Carsten A. Brandt,Ole Kierkegaard,Johnny Hindkjæ r,Peter K. A. Jensen,Sø ren Pedersen,Aage J. Therkelsen |
| Affiliation: | Institute of Human Genetics, University of Aarhus, Aarhus, Denmark;Department of Pediatrics, Central Hospital of Herning, Aarhus, Denmark;Danish Cancer Society, Department of Cytogenetics, Aarhus, Denmark |
| Abstract: | Brandt CA, Kierkegaard O, Hindkjær J, Jensen PKA, Pedersen S. Ring chromosome 20 with loss of telomeric sequences detected by multicolour PRINS. Clin Genet 1993: 44: 26–31. © Munksgaard, 1993 A ring chromosome 20 in a male infant with epileptic seizures, mental and somatic growth retardation, and behavioural disturbances is described. Conventional cytogenetics revealed the karyotype to be 46,XY,r(20)(pter→qter) and no signs of mosaicism were found. Fluorescence in situ hybridisation using the clone p20Z1 identified the ring to be derived from chromosome 20. By counting 111 metaphases, only 7% were found to be missing the ring. The absence of telomeric sequences in the ring chromosome was demonstrated by multicolour PRINS: a three-step PRimed IN Situ labelling technique, using unlabelled primers. A terminal deletion of both arms thus seems to be the cause of the ring formation in the proband. Bivariate flow-analysis of chromosomes verified a deletion of the ring chromosome. The clinical and cytogenetic findings are compared with previous cases. A specific ring 20 syndrome seems justified. |
| Keywords: | chromosome 20 PRimed IN Situ labelling ring chromosome syndrome telomeric sequences |