Objective:To explore the clinical application value of multiple cytogenetic and molecular genetic techniques in the diagnosing of chromosomal microstructural abnormalities.Methods:The proband was a 30-year-old man. He went to Reproductive Medicine Center of Shenzhen Zhongshan Urology Hospital in July 2021 because of a 7-year history of primary infertility. Chromosome karyotype was analyzed by conventional G-banding technique. One case was found to be suspected of microstructural aberration in X chromosome. The origin and structural characteristics of this X chromosome structural aberration was identified by high-resolution G-banding, copy number variation sequencing (CNV-seq), C-banding and fluorescence in situ hybridization (FISH). The pregnancy outcome of this case was followed up. Results:Conventional G-banding karyotype of peripheral blood lymphocytes was initially diagnosed as 46, Y, ?inv(X)(p22.3p22.2). The final karyotype of proband was interpreted as 46, Y, der(X) t(X; Y)(p22.3; q12) mat by high-resolution G-banding karyotype analysis, CNV-seq, C-banding analysis and FISH detection. His spouse had conceived singleton pregnancy via in vitro fertilization and embryo transfer. Prenatal diagnosis had been performed. Karyotype of amniotic fluid was 46, X, der(X) t(X; Y)(p22.3; q12) pat. No structural malformation was detected prenatally by ultrasound. The neonate was phenotypically normal one month after birth. Conclusion:The combined application of multiple cytogenetic and molecular genetic techniques can provide a reliable technical platform for characterizing the microscopic structural aberrations of chromosomes, and an important genetic basis for exploring the phenotype, prognosis and offspring risk of such patients.

Objective:To explore the clinical application value of multiple cytogenetic and molecular genetic techniques in the diagnosing of chromosomal microstructural abnormalities.Methods:The proband was a 30-year-old man. He went to Reproductive Medicine Center of Shenzhen Zhongshan Urology Hospital in July 2021 because of a 7-year history of primary infertility. Chromosome karyotype was analyzed by conventional G-banding technique. One case was found to be suspected of microstructural aberration in X chromosome. The origin and structural characteristics of this X chromosome structural aberration was identified by high-resolution G-banding, copy number variation sequencing (CNV-seq), C-banding and fluorescence in situ hybridization (FISH). The pregnancy outcome of this case was followed up. Results:Conventional G-banding karyotype of peripheral blood lymphocytes was initially diagnosed as 46, Y, ?inv(X)(p22.3p22.2). The final karyotype of proband was interpreted as 46, Y, der(X) t(X; Y)(p22.3; q12) mat by high-resolution G-banding karyotype analysis, CNV-seq, C-banding analysis and FISH detection. His spouse had conceived singleton pregnancy via in vitro fertilization and embryo transfer. Prenatal diagnosis had been performed. Karyotype of amniotic fluid was 46, X, der(X) t(X; Y)(p22.3; q12) pat. No structural malformation was detected prenatally by ultrasound. The neonate was phenotypically normal one month after birth. Conclusion:The combined application of multiple cytogenetic and molecular genetic techniques can provide a reliable technical platform for characterizing the microscopic structural aberrations of chromosomes, and an important genetic basis for exploring the phenotype, prognosis and offspring risk of such patients.