[Corrected 2/12/14, see below] Was it that airline flight? The vitamin supplements? The hair dye?
Women who have miscarried may comb their memories for reasons, and the grieving process can last more than a decade, says Barbara Pettersen, clinical director for San Carlos, CA-based diagnostics company Natera.
Most of the time, miscarriages are the result of natural processes and no one is to blame, Pettersen says. “Up to 25 percent of all conceptions will result in a miscarriage,” she says. “Most people don’t know that.”
But when genetic factors cause a miscarriage, knowing the details can help hopeful parents plan for their next pregnancy, Pettersen says.
Natera, best known for its prenatal testing products, also makes a genetic test designed to identify reasons for the loss of a pregnancy. The answer often lies in the chromosomes of the fetus, says Pettersen (pictured above right). Working with a tissue sample from the miscarriage, Natera searches 317,000 sites along the fetal DNA to look for variations that could have caused the trouble.
A large fraction of pregnancy losses are due to genetic abnormalities in the fetus that arise by chance in the early steps that lead to the development of a fertilized egg, Pettersen says. These spontaneous errors are not inherited from either of the parents. But that still leaves aspiring parents with the question, “Will it happen again?”
In some cases, miscarriages do stem from genetic variations handed down from the mother or father. Analyses of chromosomes from both parents may be needed to figure this out. The answer may make a significant difference to the odds that the next pregnancy will be successful.
Couples who have suffered more than one miscarriage are particularly interested in knowing the reasons. So are those who have lost a pregnancy created through in vitro fertilization, Pettersen says.
“If they miscarry, they want to know the cause before they go through another IVF cycle,” she says.
It was working with that population of IVF clients that first got Natera interested in creating its test for the causes of miscarriage, Pettersen says. Natera was already making genetic screening tests that help clients of in vitro fertilization clinics to decide which of the early-stage embryos created through IVF should be implanted in the womb. The company’s preimplantation genetic diagnosis test identifies embryos with chromosomal abnormalities that could prevent implantation of the embryo in the uterus, cause a miscarriage, or result in birth defects in the child.
“We just basically modified that test to look at fetal tissue from a miscarriage,” Pettersen says. Natera began marketing the test in 2010.
Natera is part of an increasingly competitive group of genomics companies offering tests related to reproduction. Natera launched a genetics-based prenatal test, Panorama, in February of 2013, as an alternative to amniocentesis and CVS. These two traditional tests are accurate but invasive, and carry a small risk of miscarriage. The Natera prenatal test requires only a blood sample from the mother—like rival prenatal tests fielded by companies including San Diego, CA-based Sequenom, San Jose, CA-based Ariosa Diagnostics, and genomics heavyweight Illumina of San Diego.
In the area of miscarriage testing, also known as products of conception testing, Natera faces competitors including Irvine, CA-based CombiMatrix, Livingston, NJ-based Reprogenetics, and Integrated Genetics, a unit of Burlington, NC-based testing giant LabCorp.
Natera’s miscarriage test delves further than a longstanding scan called a karyotype that doctors have traditionally ordered for women who have miscarried more than once. The karyotype is a stained preparation of the chromosomes in tissue collected from the miscarriage, which are visually inspected through a microscope and photographed.
The karyotype can show whether the fetus has the normal number of chromosomes—a pair of each of the 23 different types of chromosomes for a total of 46. The test can reveal whether a chromosome is missing from one of the 23 pairs, or if there’s an extra copy of a chromosome. For example, Down Syndrome results when the cells have three copies of chromosome number 21. This is also called Trisomy 21, and it often results in a miscarriage—as do certain other
