Double trisomy (48, XXY,+ 21) in a foetus associated with Atrioventricular septal defects (AVSD) and agenesis of the corpus callosum. Poster presentation in ASHG 2015, Baltimore, MD, October 6-10.

The incidence of double aneuploidy in the same individual is relatively uncommon. In addition dual aneuploidies involving both autosomal and sex chromosomes have rarely been reported to be associated with developmental defects such as congenital heart defects (CHD). Most reported cases of double aneuploidy are presented in the form of recurrent miscarriages and abortions. A 20-weeks old male fetus with double aneuploidy associated with atrioventricular septal (AVSD)and other developmental defects has been analysed. This is the first child of healthy and non-consanguineous parents, which was aborted after 20 weeks of gestation. The estimated foetal weight was 232 gm (35th percentile). Using 4-D ultrasonography, the cavum septum pellucidum in the brain was not observed. Electroencephalogram showed mildly diffuse cortical dysfunction without abnormal epileptiform discharges. Lateral ventricles were also dilated. Only a thin rim of cerebral cortex was present. Choroid plexus and medial wall of ventricle separation was 7. 2 mm (normal < 3 mm). All the conditions were suggestive of agenesis of corpus callosum. Fetal echocardiographic findings indicated congenital heart disease with atrioventricular septal defects (AVSD). Chromosomal and Fluorescence in situ hybridization (FISH) techniques with LSI21 and DYZ3 alpha satellite and CEP X alpha satellite probes analysis showed a karyotype of 48,XXY,+21: a double aneuploidy of DS and Klinefelter syndrome (KS), very few such cases have been reported in the literature. A detailed genetic and clinical report of the present case and current knowledge on causes and consequences of double aneuploidy in humans will be presented