Tehran University Medical Journal (May 2014)
Balanced reciprocal translocation 5,18: a case report
Abstract
Background: A balanced reciprocal translocation is a structural abnormality, which at least consist of breakage of two non-homologous chromosomes along with pieces exchange and form quadrivalant structure that can produce unbalanced chromosomes during meiosis I and result in a fetus abortion. The aim of the present study is to offer using preimplantation genetic diagnosis (PGD) 24sure array, which delivers aneuploidy screening of 24 chromosomes, within a few hours to increase fertility and bearing a child without chromosomal abnormality of this couple. This technique could replace embryo donation for child bearing of this couple. Case presentation: A young couple with recurrent pregnancy loss in 6th and 7th week of pregnancy without family history of recurrent miscarriage and any clinical signs had conferred. All laboratory tests including hormonal, infections, semen and hysterosalpingography were normal except karyotype that showed balanced reciprocal translocation between chromosomes 5 and 18 in male. Chromosomal study of male parents showed normal karyotype. Conclusion: A balanced reciprocal translocation carrier is phenotypically normal, but during meiosis І, carrier chromosomes cant pair normally and form quadrivalant instead of bivalant that depend on type of their segregation (alternate, adjacent 1, adjacent 2,3:1,4:0), produce gametes that are chromosomally unbalanced which can result in early fetus abortion. Considering the number of abnormal gametes, the most effective way to help couples with this problem seems to be PGD 24sure, since it can identify reciprocal and Robertsonian translocation and allows concurrent screening of all chromosomes for aneuploidy. Another technique that can be compared with PGD 24sure is fluorescence in situ hybridization (FISH), but it has several technical limitations such as it is expensive and complexity, in addition it has only few probes (for chromosomes 21, 13, 18, X, Y) so sometimes necessary to create patient specific protocols.
