Molecular Test Detects Aberrant Fetal DNA in Maternal Plasma

A laboratory-developed test (LDT) for an overabundance of chromosome 21 in maternal blood is undergoing validation.

The test involved sequencing DNA from plasma for the presence of trisomy 21, which is associated with fetal chromosome 21 aneuploidy. Trisomy 21 is linked to Down's syndrome, a genetic abnormality in which there are three copies, instead of the normal two, of the 21st chromosome. Aneuploidy is an abnormal number of chromosomes, and is a type of chromosome abnormality that occurs during cell division.

The new study is designed to evaluate the clinical performance of the SensiGene T21 LDT developed by Sequenom Inc., (San Diego, CA, USA), to detect an overabundance of chromosome 21 in maternal blood. Previously, a locked nucleic acid assay study was performed on the GAIIx sequencer (Illumina; Inc., San Diego, CA, USA). Subsequently, additional equivalency studies were performed using the more advanced Illumina HiSeq 2000 sequencer, which offers greater sample throughput.

Sequenom Center for Molecular Medicine (CMM) scientists and Sequenom's oversight committee have reviewed data from the equivalency studies and authorized the start of the LDT clinical validation study using the HiSeq 2000. Sequenom CMM in San Diego has received the first set of clinical specimens for the study and plans to start testing samples immediately. The total number of samples in this study is expected to be approximately 2,000, of which approximately 200 will be trisomy 21 positive samples.

Harry F. Hixson, Jr., PhD, chairman and chief executive officer of Sequenom, said, "We remain very pleased with the results of the 480 sample research and development verification study that was completed in September 2010. Results from our just completed HiSeq 2000 equivalency study met prespecified requirements that now allow us to proceed confidently with the validation study. The LDT clinical validation study is an important next step in confirming the trisomy 21 test performance in a large sample cohort." The results of the study have been accepted for future publication the American Journal of Obstetrics and Gynecology.

Related Links:
Sequenom Inc.
Illumina Inc.