Small Supernumerary Ring Chromosome Derived from an Inverted Duplication of 13q11.2q14 in a Fetus with Coarctation of the Aorta

Abstract

Here, we report a molecular characterization of a small supernumerary marker chromosome (sSMC) derived from the most proximal region of 13q present in a fetus with coarctation of the aorta at ultrasound examination during prenatal diagnosis. Cultured umbilical cord blood cells showed a de novo extra ring-shaped sSMC in 76% of the cells using a standard banding technique. SNP array revealed a tetrasomy of about 28.4 Mb in the long arm of chromosome 13 from band 13q11 to 13q14.11 in the fetus's cells. Metaphase/interphase FISH using specific probes located at 13q11, 13q12.11, and 13q14.11, respectively, demonstrated that the supernumerary ring chromosome was derived from an inverted duplication of the region 13q11q14.11 with a conventional centromere. To the best of our knowledge, this is the first time that an inverted duplication of the most proximal region 13q11q14.11 in a ring chromosome is characterized. The findings we presented here deepen our understanding of the clinical consequences of tetrasomy in this region and may be of help for further studies of critical regions in chromosome 13.