A unique case of a discontinuous duplication 3q26.1-3q28 resulting from a segregation error of a maternal complex chromosomal rearrangement involving an insertion and an inversion

- Underlying genes for “3q-duplication syndrome” (3qdup) are not identified yet.
- Segregation error of parental balanced translocation may lead to this syndrome.
- Here we are able to narrow down the critical region for 3qdup.

Until now, few cases of partial trisomy of 3q due to segregation error of parental balanced translocation and segregation of a duplicated deficient product resulting from parental pericentric inversion have been reported so far. Only five cases of chromosomal insertion malsegregation involving 3q region are available yet, thus making it relatively rare. In this case report, we are presenting a unique case of discontinuous partial trisomy of 3q26.1-q28 region which resulted from a segregation error of two insertions involving 3q26.1 to 3q27.3 and 3q28 regions with ~ 21 Mb and ~ 2 Mb sizes, respectively. The maternally inherited insertion was cytogenetically characterized as der(8)(8pter → 8p22::3q26 → 3q27.3::3q28 → 3q28::8p22 → 8qter) and the patient's major clinical features involved Dandy Walker malformation, sub-aortic ventricular septal defect, upslanting palpebral fissures, clinodactyly, hirsutism, and prominent forehead. Besides, a review of the literature involving cases with similar chromosomal imbalances and cases with “3q-duplication syndrome” is also provided.