What carrier screening is
Everyone carries a few silent gene variants for recessive conditions. On their own, they're harmless. A child is affected only if both parents carry a variant in the same gene, and then each pregnancy has a 1 in 4 chance. Carrier screening tests both partners to find out.
It matters because most children born with recessive conditions have no family history at all. How two healthy parents can have an affected child. In a large Australian study of over 9,000 couples, about 1 in 50 tested couples learned they were both carriers of the same condition.
What gets tested
| Approach | What it covers |
|---|---|
| Standard (ACOG) | Cystic fibrosis, spinal muscular atrophy and hemoglobin disorders (sickle cell and thalassemia) for everyone; fragile X if there's a family history; extra conditions by ancestry, such as Tay-Sachs for Ashkenazi Jewish families |
| Expanded carrier screening | Hundreds of conditions at once, for any ancestry. ACMG recommends a panel of at least 113 genes for everyone |
| Family-specific testing | If a relative has a known condition, testing for that exact variant |
Well-known expanded panels in the US include Natera Horizon, Myriad Foresight, Labcorp Inheritest and Quest QHerit. Panel sizes and gene lists differ, so compare the conditions covered, not just the number. Your doctor or a genetic counselor can order one.
Who should get it
- Anyone planning a pregnancy, according to professional guidelines.
- Especially: couples who are related (even distantly), people with a family history of a genetic condition, and people from communities with known founder conditions, such as Ashkenazi Jewish, French-Canadian, Amish, South Asian or Middle Eastern families.
- Egg or sperm donor recipients, so the donor's results can be compared with yours. More on donors.
Other tests before pregnancy
- Family history review with your doctor: conditions, early deaths, developmental delay or pregnancy losses in either family.
- Chromosome testing (karyotype) if you've had several miscarriages or a relative with a chromosome condition.
- Not before pregnancy: NIPT (cell-free DNA) screens a pregnancy for chromosome conditions like Down syndrome. It's done during pregnancy and doesn't replace carrier screening.
What it costs
Prices vary by lab and plan, and they change, so get an estimate before you test:
- With insurance: screening recommended by ACOG is often covered, especially in pregnancy. Coverage for expanded panels varies. Many labs cap what you pay out of pocket and offer financial help.
- Self-pay: many labs offer cash prices for expanded panels, often in the low hundreds of dollars per person. Ask the lab directly for its current price.
- Testing one partner first can save money: if they carry nothing significant, the other partner may need less testing. Testing both at once is faster.
Is 23andMe carrier status enough?
No. 23andMe's Health + Ancestry service includes carrier status reports for over 40 conditions, but it checks only selected variants for each one. Many conditions can be caused by hundreds of different variants, so 23andMe itself says its reports can't rule out being a carrier, and they detect more carriers in some ancestries than others.
A positive 23andMe result should be confirmed with clinical testing. A negative one isn't reassurance. A clinical carrier screen sequences the genes and covers far more conditions.
What the results mean
| Result | What happens next |
|---|---|
| Neither of you is a carrier of the same condition | Your risk for the conditions tested is greatly reduced. No test can bring it to zero |
| One of you is a carrier | Common and usually reassuring. Your partner is tested for the same gene |
| You both carry the same condition | Each pregnancy has a 1 in 4 chance. See a genetic counselor about options: IVF with embryo testing, testing during pregnancy, donor egg or sperm, or going ahead informed |
Try the carrier odds calculator to see how the numbers work for your situation.
General information, not medical advice. Talk to your doctor or a genetic counselor about which tests are right for you.
Sources
- ACOG Committee Opinion 691: Carrier screening for genetic conditions (2017)
- ACOG Committee Opinion 690: Carrier screening in the age of genomic medicine (2017)
- Gregg AR et al. Screening for autosomal recessive and X-linked conditions: ACMG practice resource. Genetics in Medicine (2021)
- Kirk EP et al. Reproductive carrier screening in 9,107 couples (Mackenzie's Mission). NEJM (2024)
- Henneman L et al. Responsible implementation of expanded carrier screening (ESHG). Eur J Hum Genet (2016)
- 23andMe: Carrier Status reports (limitations)