chromosomes

In June 2017, the Victorian Clinical Genetics Services became the first to include the assessment of all 24 chromosomes (chromosomes 1-22 + X and Y) in its non-invasive prenatal testing (NIPT) service. Most NIPT services identify pregnancies at increased chance of the common chromosome conditions such as Down syndrome, however percept™ now gives women and couples access to additional information about the health of their pregnancy. This includes the identification of less common chromosome conditions known as rare autosomal trisomies (a trisomy is three copies of a chromosome instead of two). These can have serious health implications for the pregnancy.

Many providers of NIPT do not report on the rare trisomies (those affecting chromosomes other than 21, 18 or 13). While a trisomy other than 13, 18 or 21 is rare, collectively they are found in about 1 of every 300-500 pregnancies at 10-12 weeks of gestational age, the usual time for NIPT.

The finding of a rare autosomal trisomy by NIPT can sometimes mean that only the placenta is affected with the trisomy and not the baby. This situation can still cause serious problems for the normal development of the pregnancy. Knowing this information can help doctors monitor pregnancies at increased risk for complications such as fetal growth problems and early labour. It may also provide an explanation for why some pregnancies miscarry.

VCGS has recently collaborated with Illumina’s clinical laboratory in Northern California to publish a study of nearly 90,000 pregnancies that were assessed using this advanced NIPT. The study, published in Science Translational Medicine, describes how advanced screening is providing valuable information about pregnancy health to both doctors and patients.

Pertile et al. 2017 Rare autosomal trisomies, revealed by maternal plasma DNA sequencing, suggest increased risk of feto-placental disease. Science Translational Medicine vol 9 Iss 405.

For more information about the advanced percept™ NIPT contact VCGS on [email protected]