AB183. Clinical and cytogenetic characterization of a boy with a de novo pure partial trisomy 16q24.1-24.3 and complex chromosome rearrangement

Background: Partial trisomy 16q is a rare syndrome with a wide range of manifestations. We here reported a boy patient with an inherited balanced complex chromosome rearrangement (CCR) involving chromosomes 1, 5, 12 and 13, and a de novo pure partial trisomy 16q24.1-24.3.

Methods: We performed G-banding analysis of the peripheral blood, chromosomal microarray analysis (CytoScan™ HD Array) and multiplex fluorescence in situ hybridization (M-FISH) with the SpectraVision Assay system in the family members.

Results: G-banding analysis of the patient’s peripheral blood revealed CCR involving chromosomes 1, 5, 12 and 13, the same as his phenotypically normal mother but the father’s karyotype is normal. CytoScan™ HD Array excluded any possible additional cryptic duplicated and/or deleted region in the patient or his parents. The patient has a de novo partial duplication originating from chromosome 16 involving the -4.4 Mbp 16q24.1-16q24.3 region, which spans 64 annotated genes, but the duplicated region is not present in either parent. The CCR of the patient is identical with that of his mother, with six breakpoints involving four chromosomes. However, a de novo derivative chromosome is present only in the patient; this is a translocation involving chromosomes 16 and 17, resulting in duplication of the 16q24.1-16q24.3 region. The final karyotype of the patient was interpreted: 46,XY,t(1;5;12;13), (1qter→1p33::5q34→5qter; 5pter→5q31::12q24→12qter; 12pter→12q22::13q32→13qter; 13pter→13q32::12q22→12q23::5q31→5q33::1p33→1pter), der (17) t (16,17) (17pter→17q25::16q24.1→16qter). arr16q24. 1q24.3 (85, 805, 704-90, 155, 062) ×3.

Conclusions: The duplication of the 16q24.1-24.3 region might contribute to the abnormal phenotype observed in our patient.

Keywords: Complex chromosome rearrangement; partial trisomy 16q