[Etiological analysis of a family with recurrent miscarriages caused by complex genomic rearrangement]

To investigate the genetic characteristics and clinical utility of Optical genome mapping (OGM) in resolving complex genomic rearrangements in families with recurrent pregnancy loss.

A recurrent miscarriage family which presented at both the People's Hospital of Qianxinan Buyi and Miao Autonomous Prefecture and the Affiliated Women and Children's Hospital of Ningbo University in September 2024 was selected as the study subject. Relevant clinical information was collected. Peripheral blood samples of the couple were collected for G banding karyotyping analysis, and copy number variation sequencing (CNV-seq) and OGM were used for verification. This study was approved by the Medical Ethics Committee of the Affiliated Women and Children's Hospital of Ningbo University (Ethics No.: EC2024-148).

CNV-seq in an external hospital detected a 10.67 Mb deletion in the 16q12.1q21 region, a 142.4 kb deletion in the 5p15.2 region, and a 359.55 kb duplication in the 7p22.2 region. No abnormality was found in the chromosomal karyotype of the male partner, and the initial karyotyping of the female partner suggested 46,XX,?del(16)(q12.1q22). The CNV-seq verification of her indicated only variations in the 5p15.2 and 7p22.2 fragments, and no deletion of 16q was detected. As indicated by precise OGM analysis, multiple intrachromosomal and interchromosomal translocation variations had occurred between chromosomes 10 and 16 in the female partner, with complex balanced rearrangements (including 5 transchromosomal breakpoints).

The complex balanced rearrangements of the female partner's chromosomes had occurred during meiosis, the resultant unbalanced gametes may be the cause of repeated miscarriage in this family. OGM can delineate complex rearrangement breakpoints and directions that are difficult to reveal by conventional karyotyping analysis and provide a basis for accurate reproductive genetic counseling.