Research

Complex rearranged small supernumerary marker chromosomes (sSMC), three new cases; evidence for an underestimated entity?

Vladimir Trifonov^1,2 , Simon Fluri³ , Franz Binkert⁴ , Adayapalam Nandini⁵ , Jasen Anderson⁶ , Laura Rodriguez⁷ , Madeleine Gross² , Nadezda Kosyakova² , Hasmik Mkrtchyan² , Elisabeth Ewers² , Daniela Reich² , Anja Weise² and Thomas Liehr²

¹Department of Clinical Veterinary Medicine, Madingley Road, Cambridge, CB3 OES, UK

²Institut für Humangenetik und Anthropologie, Kollegiengasse 10, D-07743 Jena, Germany

³Universitätskinderklinik, Inselspital, CH-3010 Bern, Switzerland

⁴MCL Medizinische Laboratorien, Freiburgstr 634, 3127 Niederwangen, Switzerland

⁵Department of Cytogenetics, Queensland Health Pathology Services, Herston QLD 4029, Queensland, Australia

⁶Department of Cytogenetics, Sullivan Nicolaides Pathology, Taringa QLD, Australia

⁷Estudio Colaborativo Español de Malformaciones Congénitas (ECEMC) del Centro de Investigación sobre Anomalías Congénitas (CIAC), Instituto de Salud Carlos III, Ministerio de Sanidad y Consumo, Madrid, Spain

author email corresponding author email

Molecular Cytogenetics 2008, 1:6doi:10.1186/1755-8166-1-6

Published:	15 April 2008

Abstract

Background

Small supernumerary marker chromosomes (sSMC) are present ~2.6 × 10⁶ human worldwide. sSMC are a heterogeneous group of derivative chromosomes concerning their clinical consequences as well as their chromosomal origin and shape. Besides the sSMC present in Emanuel syndrome, i.e. der(22)t(11;22)(q23;q11), only few so-called complex sSMC are reported.

Results

Here we report three new cases of unique complex sSMC. One was a de novo case with a dic(13 or 21;22) and two were maternally derived: a der(18)t(8;18) and a der(13 or 21)t(13 or 21;18). Thus, in summary, now 22 cases of unique complex sSMC are available in the literature. However, this special kind of sSMC might be under-diagnosed among sSMC-carriers.

Conclusion

More comprehensive characterization of sSMC and approaches like reverse fluorescence in situ hybridization (FISH) or array based comparative genomic hybridization (array-CGH) might identify them to be more frequent than only ~0.9% among all sSMC.