Maternal Plasma DNA Sequencing (image) NIH/National Human Genome Research Institute Share Print E-Mail Caption Conceptual image of a cell karyotype exhibiting trisomy, three copies of one chromosome. Credit Darryl Leja for NHGRI. Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.