Molecular cytogenetic characterization of de novo concomitant proximal 21q deletion of 21q11.2q21.3 and distal Xp deletion of Xp22.33p22.2 due to an unbalanced X;21 translocation detected by amniocentesis

• Main Authors: Chih-Ping Chen (Author), Shin-Wen Chen (Author), Chao-Yun Wu (Author), Schu-Rern Chern (Author), Fang-Tzu Wu (Author), Yen-Ting Pan (Author), Peih-Shan Wu (Author), Chen-Chi Lee (Author), Li-Feng Chen (Author), Wayseen Wang (Author)
• Format: Book
• Published: Elsevier, 2023-01-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 1028-4559; 10.1016/j.tjog.2022.01.009
• Keywords: Distal Xp deletion; Prenatal diagnosis; Proximal 21q deletion; X; autosome translocation; Gynecology and obstetrics; RG1-991
• Source: Taiwanese Journal of Obstetrics & Gynecology, Vol 62, Iss 1, Pp 123-127 (2023)

Objective: We present molecular cytogenetic characterization of de novo concomitant proximal 21q deletion of 21q11.2q21.3 and distal Xp deletion of Xp22.33p22.2 due to an unbalanced X; 21 translocation detected by amniocentesis. Case report: A 35-year-old, primigravid woman underwent amniocentesis at 17 weeks of gestation because of advanced maternal age. Amniocentesis revealed a karyotype of 45,X,der(X)t(X; 21) (p22.2; q21.3),-21. Simultaneous array comparative genomic hybridization (aCGH) revealed the result of an 11.9-Mb Xp22.33p22.2 deletion encompassing HCCS, SHOX, AMELX and OFD1 and a 15.4-Mb 21q11.2q21.3 deletion encompassing NRIP1 and APP. The pregnancy was subsequently terminated, and a malformed fetus was delivered with craniofacial dysmorphism. The parental karyotypes were normal. Polymorphic DNA marker analysis by quantitative fluorescence polymerase chain reaction (QF-PCR) confirmed a paternal origin of the 21q proximal deletion. Cytogenetic analysis of cord blood confirmed the karyotype of 45,X,der(X)t(X; 21) (p22.2; q21.3),-21. aCGH analysis of the cord blood confirmed the prenatal diagnosis. Conclusion: QF-PCR analysis is useful for determination of the parental origin of a de novo unbalanced X; autosome translocation detected by prenatal diagnosis. The information acquired is useful for genetic counseling under such a circumstance.