How to Cite this Article: Assawamakin A, Wattanasirichaigoon D, Tocharoentanaphol C, Waeteekul S, Tansatit M, Thongnoppakhun W, Limwongse C. 2012. A novel maternally-derived insertional translocation resulting in partial trisomy 4q13.2–q22.1 with complex translocation t(8;20) in a family with intellectual disability. Am J Med Genet Part A 158A:901–908.
A novel maternally-derived insertional translocation resulting in partial trisomy 4q13.2–q22.1 with complex translocation t(8;20) in a family with intellectual disability†
Article first published online: 14 MAR 2012
Copyright © 2012 Wiley Periodicals, Inc.
American Journal of Medical Genetics Part A
Volume 158A, Issue 4, pages 901–908, April 2012
How to Cite
Assawamakin, A., Wattanasirichaigoon, D., Tocharoentanaphol, C., Waeteekul, S., Tansatit, M., Thongnoppakhun, W. and Limwongse, C. (2012), A novel maternally-derived insertional translocation resulting in partial trisomy 4q13.2–q22.1 with complex translocation t(8;20) in a family with intellectual disability. Am. J. Med. Genet., 158A: 901–908. doi: 10.1002/ajmg.a.35259
- Issue published online: 23 MAR 2012
- Article first published online: 14 MAR 2012
- Manuscript Accepted: 23 DEC 2011
- Manuscript Received: 28 OCT 2010
- The Thailand Research Fund (TRF)
- chromosome 4;
- insertional translocation;
- partial trisomy 4q;
We characterized the chromosomal aberration in family with intellectual disability, including two affected children and their affected mother. Initial standard karyotypes of the three individuals showed an apparently balanced translocation of chromosomes 8 and 20. Using molecular cytogenetic techniques, we observed complex structural chromosomal aberration comprising of reciprocal translocation between chromosomes 8 and 20 with pericentric inversion (8p11.12q22.3) and insertion of chromosome 4 segments into both der(8) and der(20). In particular, the insertion of chromosome 4 was complex. Two segments (4q13.2–q13.3 and 4q21.21–q22.1) were inserted into the der(8)t(8;20) breakpoint and one segment (4q13.3–q21.21) into the der(20)t(8;20) breakpoint. Both children inherited two normal chromosomes 4 from their parents and the der(8) and der(20) from the mother, resulting in partial trisomy of 4q13.2–q22.1. Interestingly, the mother, in addition to the same complex insertions and inversion, was founded to have a deletion of 4q13.2–q22.1 in one of her chromosomes 4, yielding no genetic imbalance but with potential disruption of intellectual dysfunction-related gene(s) at the breakpoints as the cause of her intellectual impairment. This family is the third case report of an insertional translocation mechanism causing partial trisomy 4q syndrome. Our study demonstrates that an insertion of an extra chromosomal segment, not primarily involving in translocation breakpoints, which results in partial trisomy, can be an unapparent cause of the abnormal phenotypes. © 2012 Wiley Periodicals, Inc.