Breakpoint mapping in a case of mosaicism with partial monosomy 9p23 --> pter and partial trisomy 1q41 --> qter suggests neo-telomere formation in stabilizing the deleted chromosome.
We report on a clinical and molecular cytogenetic study of a patient who presents a complex chromosomal rearrangement with two different cell lines. Using high-resolution GTG banding and fluorescence in situ hybridization (FISH) with several probes, including bacterial artificial chromosomes (BACs), the karyotype was defined as 46,XX,del(9)(p23)[54]/46,XX,der(9)t(1;9)(q41;p23)[46], indicating the presence of monosomy 9p23 in all cells and trisomy 1q41 in approximately 50% of the cells. The patient studied presents most of the manifestations of the 9p deletion and 1q duplication syndromes. The breakpoint was mapped at 9p23 with a loss of approximately 13.9-Mb of DNA. The duplicated segment consists of approximately 35 Mb from 1q41-qter region. We also suggest that a mechanism for telomere capture and interstitial telomeric sequences (ITs) is involved in a neo-telomere formation in one of the cell lines. This study highlights the importance of combining high-resolution chromosome and FISH with BACs in order to make genotype-phenotype correlations and to understand the mechanisms involved chromosomal aberrations.
Kulikowski
Leslie D
LD
Genetics Division, Department of Morphology, Universidade Federal de São Paulo, Rua Botucatu 740, 04023-900 São Paulo, SP, Brazil.
Christ
Laurie A
LA
Nogueira
Sintia I
SI
Brunoni
Decio
D
Schwartz
Stuart
S
Melaragno
Maria I
MI
D002648:Child; D002869:Chromosome Aberrations; D002871:Chromosome Banding; D019457:Chromosome Breakage / Q000235:genetics; D002872:Chromosome Deletion; D002878:Chromosomes, Human, Pair 1 / Q000235:genetics*; D002899:Chromosomes, Human, Pair 9 / Q000235:genetics*; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008957:Models, Genetic; D009006:Monosomy; D009030:Mosaicism; D016615:Telomere / Q000235:genetics*; D014178:Translocation, Genetic; D014314:Trisomy