[Diagnosis of a case of complex chromosomal rearrangement by optical genome mapping]

To analyze a patient with infertility due to complex chromosome rearrangement by optical genome mapping (OGM).

A female patient who was diagnosed with "primary infertility" at Shenzhen Longhua District Maternal and Child Health Care Hospital in April 2024 was selected as the study subject. Clinical data of the patient was collected. Chromosome G banding karyotyping analysis was carried out for the patient and her parents, in addition with OGM and copy number variation sequencing (CNV-seq). This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: 2023052504).

The patient, a 33-year-old female, had infertility for the past 5 years. OGM revealed formation of two derivative chromosomes through rearrangement of chromosomes 5 and 18. A loss of heterozygosity on chromosome 5 was also detected by OGM and CNV-seq techniques. Both of her parents had a normal karyotype.

The OGM technique can refine the position of chromosomal breakpoints and determine the direction and position of insertional fragment. Combined with karyotype analysis, the OGM can accurately determine the chromosomal karyotype of the patient and facilitate genetic counseling.