At my first Obstetrician appointment at 10 weeks we talked about the options for genetic screening. My first homework assignment was to go away and figure out what we would like to screen for….in addition to finding out what our insurance would cover.
Aneuploidy Testing: These are the tests available for screening Trisomy 21 (Down Syndrome), Trisomy 18 (Edward’s Syndrome), Trisomy 13 (Patau Syndrome) and open neural tube defects (i.e. Spina bifida and anencephaly).
My OB offers three options for screening:
- NIPT- Non Invasive Prenatal Testing (i.e. Harmony or Verify). This is a simple and accurate non invasive prenatal screening blood test. The test can be performed anytime after 10 weeks of gestation. In addition an AFP (alpha-fetoprotein) blood test to test for neural tube defects is also taken at this time. It is also possible to discover the gender of your baby through this test. Approximate cost $825.
- Sequential Screening with Nuchal Translucency. This is a two-step test to detect whether a fetus is at increased risk. The test has a narrow window for testing (first step is performed between 10-13 weeks of gestation). It includes 2 blood draws and an ultrasound. The ultrasound measures the amount of fluid behind the baby’s neck (called the nuchal translucency NT). The blood tests measures three different hormone levels, these measurements in combination with maternal information such as height and weight are used to calculate the baby’s risk of Down’s Syndrome or Edward’s Syndrome. The AFP blood test (described in 1) is also taken. Approximate cost $580
- Quad Screen (aka quadruple marker test). This is a blood test that measures levels of four substances in a pregnant woman’s blood – AFP, hCG, Estriol and Inhibin A. typically this screen is done between weeks 15 and 20 of gestation. Approximate cost $305.
If any of tests come up with a positive result then additional testing can be performed (These are the more invasive tests you may hear about such as CVS or amniocentesis where the doctor extracts a sample of the baby’s cells from the uterus. Amniocentesis is where a thin needle is inserted through the belly and into the amniotic sac to take a sample of the amniotic fluid. CVS is where the doctor uses a needle through the belly or cervix and takes some placenta cells. These tests carry a very small risk of miscarriage).
Additional Screening Offered:
- Cystic Fibrosis. Cystic fibrosis is the most common inherited disease of children and young adults. The carrier frequency is 1 in 24, to 1 in 97. Both parents need to be carriers for a child to be affected (25% chance). 1 in 2500 children born are affected. Cystic Fibrosis is a disorder of mucus production and produces abnormally thick mucus leading to life threatening lunc infections, digestion problems, poor growth, infertility and more. Symptoms range from mild to severe, but individuals with severe disease may die in childhood. With treatments today, people with Cystic Fibrosis can live in their 30s. Cystic Fibrosis does not affect intelligence. Approximate cost $800.
- Spinal Muscular Atrophy (SMA). SMA is the most common inhered cause of early childhood death. The carrier frequency is 1 in 47 to 1 in 73 in the US and both parents need to be carrier or a child to be affected (25% chance). 1 in 11,000 children are affected. SMA is a progressive degeneration of lower motor neurons. Muscle weakness is the most common type with respiratory failure by the age of 2 years old. Muscles responsible for crawling, walking, swallowing, and head and neck control are most severely affected. Approximate cost: $625.
- Fragile X Syndrome (the most common inherited cause of developmental delays). Fragile X syndrome is an ‘X-linked’ genetic disease which means it is only carried by the mother. Unfortunately, 1 in 250 females are carriers and a child has a 50% chance of being affected if this is the case. 1 in 4000 boys is affected with Fragile X and 1 in 8000 girls. Approximately 1/3 of all children born with fragile X also has autism and hyperactivity. Approximate cost $390.
What have we decided?
We decided we would like to do the NIPT (Non Invasive Prenatal Testing) for the aneuploidy testing. Why? The accuracy is significantly higher than the other two tests and the false positive rate is very low (0.1%) compared to the other two tests (sequential screening rate is 3.5%, quad screen rate is 5%). Our insurance also covers it, plus it would be nice to have an idea of the gender – although that is a Brucie Bonus because the chances are we are going to wait until a lot later for a gender reveal party, so we are in no hurry!
We will also ask for Fragile X syndrome screening too because one of my brothers has autism and my mum doesn’t know if she is a carrier, so it makes sense to take the test.
My next OB appointment is tomorrow – Monday – afternoon to talk through what we would like to do and to go over my blood test results from my first appointment (they all came back clear, including my slight anemia which I was worried about, so that’s good). If I have my blood drawn tomorrow then the results will take 2 weeks to come back. Another 2 week wait!!
On a side note, I didn’t know much about Down’s syndrome, Edward’s syndrome or Patau syndrome….so I had a read about it all. It’s very interesting to find out more and I’m glad I have educated myself about these a bit more.