ObjectiveTo explore the application value of chromosome G-banding karyotype analysis combined with genome-wide copy number variation sequencing (CNV-seq) in prenatal diagnosis of sex chromosome abnormalities.

MethodsFrom January 2022 to January 2024, 370 pregnant women who underwent amniocentesis in the Medical Genetics Center of Northwest Women and Children’s Hospital due to free DNA detection of fetuses in peripheral blood of pregnant women who had sex chromosome abnormalities were collected. Amniotic fluid samples were collected and analyzed for chromosome G-banding karyotype analysis and CNV-seq technology detection.

ResultsAmong 370 pregnant women, a total of 114 sex chromosome abnormalities were detected by karyotype analysis, the detection rate was 30.8%, of which 94 were aneuploidy abnormalities, including 47, XXY 42 cases, 47, XXX 30 cases, 47, XYY 22 cases, the main abnormality was 47, XXY, accounting for 36.8% (42/114). There were 5 cases with abnormal structure, accounting for 4.4% (5/114). There were 15 cases of chimera, accounting for 13.2% (15/114).A total of 123 cases of sex chromosome abnormality were detected by CNV-seq technique, the detection rate was 33.2%, including 94 cases of sex chromosome aneuploidy abnormality, which was consistent with the karyotype results, and 9 cases of microdeletions/microduplications not detected by karyotype analysis were detected, of which 7 cases were of unknown clinical significance and 2 cases were pathogenic mutations.

ConclusionsChromosome karyotype analysis can detect the number of chromosomes and the structural abnormalities of large fragments, CNV-seq technology can detect the small duplication and deletion of chromosomes, and accurately locate the structural abnormalities of chromosomes. Both having advantages and complement each other in the diagnosis of sex chromosome abnormalities, can further improve the detection rate of sex chromosome abnormalities, and provide accurate test results for clinical diagnosis of chromosomal diseases.