UBC Theses and Dissertations
Characterization of an inversion duplication of human chromosome 8 by fluorescent in situ hybridization Henderson, Karen Gwen
A. de novo chromosomal aberration in a female with severe mental retardation and dysmorphic features has been characterized cytogenetically (Dill et al. 1987). The patient’s karyotype was described as 46,XX,inv dup(8)(p12→23.1). Previous Southern blot dosage analysis of the patient’ s DNA with a probe from the D8S7 locus, which maps to 8p23→8pter (Wood et al. 1986), demonstrated that the patient was monosomic for this locus. This dosage abnormality was interpreted as a consequence of the chromosomal rearrangement, suggesting that the aberrant chromosome was a duplication deficiency chromosome. We have reinvestigated this patient using fluorescent in situ hybridization using cosmids from a flow sorted chromosome 8 library as well as an 8p painting probe mixture generated by Mu element mediated PCR. Both the normal and the inversion duplication chromosome p arms are uniformly labelled by the 8p painting probe mixture. Hybridization of a cosmid from the D8S7 locus results in a hybridization signal on the normal chromosome 8 and a complete lack of signal on the inversion duplication chromosome 8. Hybridization of a cosmid from the D8S133 locus, localized to 8p21→8cen using a hybrid cell panel (Wagner et al. 1991), provides a single hybridization signal on the normal chromosome 8 and a double hybridization signal on the aberrant chromosome. The pattern produced by this double signal is suggestive of an inversion duplication chromosome. These studies directly confirm both the origin of the extra chromosomal material and that the duplication chromosome has undergone deletion.
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