This study presents a case of a male carrier with a cryptic complex chromosomalrearrangement (CCR) incidentally identified by next-generation sequencing (NGS)-based preimplantation genetic testing (PGT), along with a literature review. The couple underwent PGT because of the male partner's known balanced translocation karyotype [46,XY,t(8;14)(p21;q13)]. Embryonic copy number variation (CNV) analysis unexpectedly revealed two distinct breakpoints on chromosome 8 in the male partner, suggesting additional structural abnormalities beyond the documented translocation. Modified high-resolution G-banding analysis of peripheral blood lymphocytes confirmed these findings. The male partner's high-resolution karyotype was ultimately characterized as 46,XY,der(8)inv(8)(p22q12.2)t(8;14)(p22;q21.3),der(14)t(8;14). The modified high-resolution G-banding technique demonstrated enhanced detection of cryptic CCRs, reducing diagnostic oversight. This case demonstrates that PGT analysis of abnormal embryonic CNV results can uncover previously undetected chromosomal abnormalities, thereby improving genetic counseling and reproductive decision-making.

This study presents a case of a male carrier with a cryptic complex chromosomalrearrangement (CCR) incidentally identified by next-generation sequencing (NGS)-based preimplantation genetic testing (PGT), along with a literature review. The couple underwent PGT because of the male partner's known balanced translocation karyotype [46,XY,t(8;14)(p21;q13)]. Embryonic copy number variation (CNV) analysis unexpectedly revealed two distinct breakpoints on chromosome 8 in the male partner, suggesting additional structural abnormalities beyond the documented translocation. Modified high-resolution G-banding analysis of peripheral blood lymphocytes confirmed these findings. The male partner's high-resolution karyotype was ultimately characterized as 46,XY,der(8)inv(8)(p22q12.2)t(8;14)(p22;q21.3),der(14)t(8;14). The modified high-resolution G-banding technique demonstrated enhanced detection of cryptic CCRs, reducing diagnostic oversight. This case demonstrates that PGT analysis of abnormal embryonic CNV results can uncover previously undetected chromosomal abnormalities, thereby improving genetic counseling and reproductive decision-making.