VERAgene for expecting parents

NIPT is a screening test taken by a pregnant woman to check for genetic conditions of the fetus before birth. NIPT analyzes cell-free DNA  in the mother’s blood to identify these genetic conditions. NIPT is important because it provides a safe and accurate way to test the baby before birth for genetic disorders, the most common of which is Down syndrome. Before the introduction of this revolutionary test, the options to test for Down syndrome were either screening methods like ultrasound combined with biochemical testing which have low accuracy (approximately 80-95%) or high accuracy prenatal diagnosis that uses invasive methods [e.g. amniocentesis or chorionic villi sampling (CVS)] which have 0.5% risk for miscarriage.

The human genome is sorted into twenty-three pairs of chromosomes. Genetic conditions are caused by unwanted changes in the genome that happen during conception. There are three types of genetic conditions:

• aneuploidies are genetic conditions that occur when a chromosome has an extra copy (trisomy) or is missing a copy (monosomy)
• microdeletions are genetic conditions caused by the deletion of part of a chromosome
• single gene diseases are genetic conditions caused by pathogenic alterations (mutations) in a gene

VERAgene is the only non-invasive prenatal test that can simultaneously screen for aneuploidies, microdeletions and single gene diseases. The diseases screened by VERAgene are associated with moderate to severe phenotype with significant impact on the quality of life. These genetic diseases exhibit symptoms such as congenital anomalies, development delays, hearing loss, blindness, metabolic disorders, etc.

VERAgene can screen for trisomies such as  Down syndrome, Edwards syndrome, Patau syndrome, sex chromosome aneuploidies, microdeletions such as DiGeorge syndrome, 1p36 deletion syndrome, Smith-Magenis syndrome and Wolf-Hirschhorn syndrome and 50 monogenic disorders such as beta thalassemia, cystic fibrosis, Tay-Sachs disease, Canavan disease, sickle cell anemia, familial Mediterranean fever, phenylketonurea, etc.  By combining detection of aneuploidies and microdeletions with the screening of monogenic disorders, VERAgene provides a comprehensive picture of the pregnancy using a single test.

Down syndrome, Edwards syndrome and Patau syndrome are genetic disorders caused by chromosomal trisomies. Down syndrome is caused by an extra copy of chromosome 21 whereas Edwards syndrome and Patau syndrome are caused by an extra copy of chromosome 18 and chromosome 13, respectively. Down syndrome is characterized by intellectual impairment and congenital abnormalities. Down syndrome occurs approximately in 1 in 700 pregnancies but is more frequent in pregnancies in women over 35. Edwards syndrome and Patau syndrome are less common occurring in 1 in 3000 and 1 in 10000 pregnancies, respectively. Edwards and Patau syndromes are characterized by severe congenital abnormalities and rarely survive past the first year of life.

Sex chromosome aneuploidies are genetic diseases caused by the presence or absence of a sex chromosome. The 23rd pair of chromosomes determine the sex of an individual. Women have two X chromosomes and men have one X and one Y chromosome. There are four major sex chromosome aneuploidies:

• Turner syndrome is characterized by the presence of a single X chromosome.
• Triple X syndrome is characterized by the presence of three X chromosomes.
• Klinefelter syndrome is characterized by the presence of two X chromosomes and one Y chromosome.
• Jacob syndrome is characterized by the presence of one X chromosome and two Y chromosomes.

Microdeletions are genetic conditions caused by the loss of a part of a chromosome. Microdeletions are characterized by congenital abnormalities and intellectual impairment. The severity of the symptoms varies depending on the size and location of the microdeletion. The most common microdeletion syndrome is DiGeorge syndrome which occurs approximately once in 1000 pregnancies. The prevalence of DiGeorge syndrome increases to 1 in 100 in pregnancies with major structural anomalies such as congenital heart disease.

Monogenic disorders are caused by mutations in a single gene. Such conditions can be either autosomal dominant which  are caused when the mutation exists on only one chromosome, or autosomal recessive where the mutation needs to be present in both chromosomes. VERAgene analyses 500 mutations to detect 50 autosomal recessive monogenic disorders.

Unlike aneuploidies, microdeletions and single gene diseases do not have an age associated risk, chemical or ultrasound biomarkers that can help in early detection. The cumulative risk for the fetus to have one of the monogenic conditions screened by VERAgene is 1 in 354, and is higher in some ethnic populations where some of the conditions are more prevalent. VERAgene can accurately screen for these conditions to help parents take informed decisions about possible treatments and clinical management.

Please contact your doctor or healthcare provider for additional information.