Optical genome mapping enhances cytogenetic analysis in recurrent miscarriage: confirmation of a suspected (1;10) chromosomal translocation.

Background: Optical genome mapping (OGM) is a next-generation cytogenetic technique that may be beneficial for detecting subtle structural chromosomal alterations that can go unnoticed with conventional studies in couples with recurrent pregnancy loss.

Case presentation: We report the case of a couple referred to our assisted reproduction unit due to a history of recurrent pregnancy loss. Initially, conventional cytogenetic studies were performed to identify a possible genetic cause. To this end, the karyotypes of both members of the couple were determined. The fetal tissue from the third miscarriage was analyzed using comparative genome hybridization (CGH) array. Subsequently, the cytogenetic analysis of the couple was extended with the OGM technique. Basic infertility studies revealed normal results, and the karyotypes of both partners were initially reported as normal with respect to structural abnormalities. Following the third miscarriage, an array CGH analysis of the abortive tissue detected a deletion-duplication on chromosomes 1 and 10, respectively. Moreover, OGM revealed a balanced translocation between chromosomes 1 and 10 in the male which had not been detected through conventional karyotyping. A retrospective review of the karyotype by an expert cytogeneticist identified an apparent translocation that had previously gone unrecognized.

Conclusions: Structural chromosomal abnormalities may be underestimated in couples experiencing multiple miscarriages because they are not always accurately recognized by conventional cytogenetic techniques. OGM offers a valuable complement to these traditional methods by identifying chromosomal alterations that may have been overlooked by karyotyping, precisely characterizing the nature of the structural rearrangements. While OGM cannot currently replace karyotyping due to limitations such as the inability to detect certain translocations (e.g., Robertsonian translocations), it can enhance diagnostic accuracy and provide additional insights into the genetic causes of repeated pregnancy loss. Therefore, OGM may serve as a useful supplementary tool for improving diagnosis and management in affected couples.