Pick your ancestries.
This is only a few conditions. A carrier screen checks hundreds at once, and about 1 in 50 couples on a large panel share at least one.
Check our carriersCommon carrier conditions by ancestry.
Approximate carrier rates. Being a carrier is usually harmless to you. It matters when your partner carries the same condition.
| Ancestry | Common carrier conditions (approximate carrier rate) |
|---|---|
| White / European | Cystic fibrosis: 1 in 25 Spinal muscular atrophy (SMA): 1 in 47 |
| Black / African American | Sickle cell trait: 1 in 13 Cystic fibrosis: 1 in 61 Spinal muscular atrophy (SMA): 1 in 72 |
| Hispanic / Latino | Cystic fibrosis: 1 in 58 Spinal muscular atrophy (SMA): 1 in 68 |
| Ashkenazi Jewish | Tay-Sachs disease: 1 in 30 Familial dysautonomia: 1 in 32 Canavan disease: 1 in 40 Cystic fibrosis: 1 in 24 Spinal muscular atrophy (SMA): 1 in 67 |
| South Asian (Indian, Pakistani, Bangladeshi, Sri Lankan) | Thalassemia trait: 1 in 15–30 Spinal muscular atrophy (SMA): 1 in 52 |
| Mediterranean (Greek, Italian, Cypriot, Maltese) | Thalassemia trait: 1 in 7–30 Cystic fibrosis: 1 in 25 Spinal muscular atrophy (SMA): 1 in 47 |
| Middle Eastern / North African | Thalassemia trait: 1 in 15–50 |
| East Asian (Chinese, Korean, Japanese) | Spinal muscular atrophy (SMA): 1 in 59 Cystic fibrosis: 1 in 94 |
| Southeast Asian (Filipino, Vietnamese, Thai and others) | Thalassemia trait: 1 in 5–30 Spinal muscular atrophy (SMA): 1 in 59 |
| Mixed or another background | Spinal muscular atrophy (SMA): 1 in 40–60 |
Rates are averages from ACOG, a pan-ethnic SMA study, CDC and WHO data. Thalassemia varies widely between communities, so it is shown as a range. Fragile X is different: about 1 in 150 to 250 women carry a premutation, whatever their ancestry. How Fragile X works.
How the odds work
For a recessive condition, a child is only affected if they get an altered copy from both parents. So the chance per pregnancy is: the chance partner 1 is a carrier × the chance partner 2 is a carrier × 1 in 4. Two white partners: 1 in 25 × 1 in 25 × 1 in 4 = about 1 in 2,500 for cystic fibrosis, which is close to how often it really happens.
That sounds small. But it's one condition. Screens look at hundreds, and the small odds add up: in a study of 9,107 couples screened on a large panel, about 1 in 50 found they shared a risk. Most had no idea. Why healthy parents can have a child with a genetic condition.
Sources
- ACOG Committee Opinion 691: Carrier screening for genetic conditions (2017)
- Sugarman EA et al. Pan-ethnic carrier screening and prenatal diagnosis for spinal muscular atrophy. Eur J Hum Genet (2012)
- CDC: Data and statistics on sickle cell disease (trait and disease rates)
- Modell B, Darlison M. Global epidemiology of haemoglobin disorders. Bulletin of the WHO (2008)
- Colah R et al. Global burden, distribution and prevention of β-thalassemias in India (2014)
- 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)
- Bennett RL et al. Genetic counseling and screening of consanguineous couples and their offspring (NSGC). J Genet Couns (2002)
General information, not medical advice. A genetic counselor can interpret your own family history and results.
Carrier questions.
What does it mean to be a carrier?
A carrier has one altered copy of a gene for a recessive condition and one working copy. Carriers are usually healthy and most have no family history. If both partners carry the same condition, each pregnancy has a 1 in 4 chance of a child with that condition.
How accurate is this calculator?
It uses average carrier rates for each ancestry, so it gives a rough picture, not your personal result. Real carrier rates vary by family and community, and mixed ancestry changes the odds. Only a carrier screen tells you what the two of you actually carry.
If our odds look low, do we still need a carrier screen?
This calculator only shows a few common conditions. A carrier screen checks hundreds at once, and about 1 in 50 couples screened on a large panel share at least one condition. Medical guidelines (ACMG 2021) recommend offering screening to everyone planning a pregnancy.
Does being related change the odds?
Yes. Related couples are more likely to carry the same rare condition from a shared ancestor. First-cousin couples have about 1.7 to 2.8 percentage points of extra risk for a serious condition, on top of the 2 to 3% every couple has.
What can we do if we are both carriers?
You have options, and a genetic counselor walks you through them: IVF with embryo testing, testing during pregnancy, using donor eggs or sperm, adoption, or going ahead with full information. Most carrier couples still have healthy children: each pregnancy has a 3 in 4 chance of a child without the condition.