[Genetic analysis of a Chinese pedigree affected with complex chromosomal structural variants]

To explore the mechanism and clinical manifestations of a case with complex structural variations involving chromosomes 5, 7, and 14, and assess the value of Chromosome conformation-based karyotyping (C-MoKa) for its diagnosis.

Two half-sibs by the same father presented at the First Hospital of Lanzhou University in December 2024 for severe multi-system abnormalities were selected as study subjects. Peripheral blood samples from the their parents were subjected to conventional chromosomal karyotyping analysis. The father was further analyzed using C-MoKa, while both siblings underwent copy number variation sequencing (CNV-seq). This study was approved by the Medical Ethics Committee of the Hospital (Ethics No.: LDYYSZLLKH2025-05).

Conventional karyotype analysis indicated that the father has a karyotype of 46,XY,add(5)(p15.3). CNV-seq identified multiple chromosomal abnormalities in both siblings, including duplications and deletions of chromosomes 14 and 5. C-MoKa analysis further revealed a complex chromosomal structural variation involving chromosomes 5, 7, and 14 in the father. These variations were closely associated with the severe phenotypes noted in both children.

Complex chromosomal structural variations can lead to multi-system abnormalities and significantly impact reproductive health. Compared to conventional karyotyping, the C-MoKa technique has shown significant advantage in identifying such complex rearrangements. The combined application of multiple techniques can improve the accuracy of diagnosis, enabling genetic counseling for carriers to reduce their risk for producing further affected offspring.