Objective: To analyze genomic copy number variations in an infant with Cri du Chat syndrome, and to explore the underlying genetic cause.
Methods: G-banding analysis was carried out on cultured peripheral blood sample from the patient. Copy number variation analysis was performed using microarray comparative genomic hybridization, and the result was verified with fluorescence in situ hybridization.
Results: The infant was found to have a 46, XY, der(5) (p?) karyotype. By microarray comparative genomic hybridization, a 23.263 Mb deletion was detected in 5p14.2-p15.3 region in addition to a 14.602 Mb duplication in 12p31 region. A derivative chromosome was formed by rejoining of 12p31 region with the 5p14.2 breakpoint. The patient therefore has a karyotype of arr cgh 5p15.3p14.2 (PLEKHG4B>CDH12)× 1 pat, 12p13.33p13.1 (IQSEC3>GUC Y2C)× 3 pat. Loss of distal 5p and gain of distal 12p were verified with fluorescence in situ hybridization.
Conclusion: The Cri du Chat syndrome manifested by the patient was caused by deletion of distal 5p from an unbalanced translocation involving chromosome 5. Microarray comparative genomic hybridization is a powerful tool for revealing genomic copy number variations for its high-resolution, high-throughput and high accuracy.