engleski

Complex chromosome rearrangements in prenatal diagnosis

Complex chromosome rearrangements (CCR) are defined as reciprocal exchanges between three or more chromosomes. It has been observed that most CCR carriers are female. CCr are very rare, with the risk for phenotypic abnormalities increasing as the number of chromosomes and chromosomal breaks involved in the rearrangement increases. The normal phenotypes of such balanced carriers CCRs suggests that presented breakpoints are not in gene regulatory or critical functional chromosomal regions. We report pregnancy outcomes and prenatal diagnosis of three cases with CCRs. A de novo complex chromosomal rearrangement involving chromosomes 4, 7 and 14 was detected prenatally at 18 weeks of gestation made for advanced maternal age. Using routine cytogenetic analysis of cultured amniotic fluid cells with GTG-banding, it was found interstitial deletion of band 4p15.2→ 15.32 and reciprocal translocation t(7 ; 14)(p13 ; q11.2), but it was impossible to be correct karyotypically determined. Fluorescent in situ hybridisation (FISH) with centromeric and "painting" chromosome - specific probes was used to explain this rare chromosome rearrangement. The chromosome 4 paint reveald chromosome 4 material inserted in derived chromosome t(7/14). In two cases mothers had a balanced complex chromosome rerrangement, detected through abnormal offspring and spontaneous abortions. The karyotype of CCR carrier was determinated as 46, XX, t(1 ; 8 ; 9)(q25q41 ; q13 ; p22), and the other as 46, XX, t(4 ; 8 ; 15)(p15p16 ; p11 ; q13). Although balanced carriers of CCR have a relativly high risk of producing unbalanced gametes, prenatal diagnosis in those cases showed that thay can have healthy offspring.

Complex chromosome rearrangements; Prenatal diagnosis

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