RESUMEN
The 48, XXY/+18 is a very rare aneuploidy syndrome which combines the aberration in both autosome and sex chromosome. The authors report a case diagnosed prenatally by lymphocyte culture from fetal blood samples following cordocentesis, 2-dimensional (2DUS) and 3-dimensional ultrasonography (3DUS). At 33 1/7 weeks gestation in an ultrasound examination by indication large for date; single umbilical artery with absence of the left umbilical artery, polyhydramnios and fetal growth restriction were demonstrated. The fetus presented with microcephaly, prominent occiput, low-set ears, micrognathia, hypertelorism, small mouth, bilateral club hands with overlapping fingers, rocker-bottom feet. Karyotyping from the cordocentesis led to the diagnosis of 48, XXY/+18, which was confirmed by the chromosomal analysis of the umbilical cord blood after the baby was born. This is the first reported case of the very rare aneuploidy syndrome in the literature.