Trisomy 18q-. Trisomy mapping of chromosome 18 revisited

Two patients with trisomy for 18p and the proximal segment of 18q (trisomy 18q-) are reported and compared with similar cases from the literature. The phenotype of trisomy 18q- resembles that of full trisomy 18 but differs mainly in the birdlike face, small mouth, more pronounced microretrognathia, minor skeletal dysplasia and inner organ malformations, and less sever vital prognosis.