Carrier Screening Result
You Are a Carrier for
Spinal Muscular Atrophy
✓ You are healthy. This result is about a gene you carry — not your health.
Your care team is here to explain what this means and what comes next.
Atlanta Perinatal Associates
What Is Spinal Muscular Atrophy?
🧬
Genetic
Caused by changes in the SMN1 gene
⚡
Motor Nerves
Affects nerve cells that control muscles
💪
Muscle Weakness
Progressive weakness in affected children
SMA is the leading inherited cause of infant death. Early detection now enables life-changing treatment.
Atlanta Perinatal Associates
SMA Varies in Severity
| Type |
Onset |
Severity |
| Type 1 (most common) |
Birth – 6 months |
Severe; affects breathing |
| Type 2 |
7 – 18 months |
Moderate; can sit, not walk |
| Type 3 |
>18 months |
Mild; walks independently |
| Type 4 |
Adulthood |
Very mild; normal lifespan |
Severity depends on the number of copies of the SMN2 backup gene.
Atlanta Perinatal Associates
What Does "Carrier" Mean?
You are completely healthy.
Your working copy protects you from having SMA.
Everyone has two copies of the SMN1 gene. Carriers have one working copy and one changed copy.
Atlanta Perinatal Associates
How Common Are Carriers?
1 in 50
people in the general population carry an SMN1 variant
✓ You did nothing to cause this. Carrier status is a normal genetic variation — not a disease.
ACOG recommends SMA carrier screening for all individuals who are pregnant or planning pregnancy.
Atlanta Perinatal Associates
How Is SMA Inherited?
SMA is autosomal recessive — a child can only have SMA if both parents pass on a changed copy.
👩
You
Carrier
1 changed copy
+
=
❓
Baby's Risk
Depends on partner's carrier status
⚡ The most important next step is partner testing.
Atlanta Perinatal Associates
If Both Parents Are Carriers
Each pregnancy:
25% — Unaffected, not a carrier
These odds apply independently to each pregnancy.
Atlanta Perinatal Associates
What Are the Chances?
| If Your Partner Is… |
Chance Baby Has SMA |
Recommendation |
| Not a carrier |
Extremely low |
Routine prenatal care |
| A carrier |
25% (1 in 4) per pregnancy |
Discuss diagnostic options |
| Not yet tested |
Unknown |
Partner testing recommended now |
Partner testing is a simple blood or saliva sample. Results typically return in 1–2 weeks.
Atlanta Perinatal Associates
If Both Parents Are Carriers
You will have options. We will guide you through each one.
During Pregnancy
CVS — Chorionic villus sampling
Weeks 10–13
Amniocentesis
Week 15 or later
Diagnostic — tells us if baby has SMA
Before Pregnancy
IVF + PGT
Preimplantation Genetic Testing
Tests embryos before transfer — selects unaffected embryos
Prevents transmission before pregnancy begins
✓ You will have choices. We will support you through every decision.
Atlanta Perinatal Associates
Prenatal Diagnostic Testing
10
CVS
Weeks 10–13
Placental tissue sample
15
Amniocentesis
Week 15+
Amniotic fluid sample
🧬
PGT-M
Before pregnancy
IVF embryo testing
CVS and amniocentesis are diagnostic — they confirm whether the fetus has SMA.
All procedures carry a small procedural risk. We will review these with you in detail.
Atlanta Perinatal Associates
Newborn Screening & Treatment
🌟 SMA is now on the Newborn Screening Panel in all 50 states. Early treatment is transformative.
Spinraza® (Nusinersen)
Intrathecal injection
Increases SMN protein production
FDA approved 2016
Zolgensma® (OAV101)
One-time gene therapy
Replaces the missing SMN1 gene
FDA approved 2019; age <2 years
Treatment before symptom onset — enabled by newborn screening — dramatically improves outcomes.
Atlanta Perinatal Associates
Understanding Your Test Result
Standard SMA carrier screening detects approximately 90–95% of carriers.
What the Test Detects
Reduced copies of the SMN1 gene (1+0 genotype) — the most common carrier pattern
What It May Miss
"Silent carriers" (2+0 genotype) — two copies on one chromosome, zero on the other
A negative partner result significantly reduces — but does not eliminate — residual risk. We will review your specific residual risk together.
Atlanta Perinatal Associates
What Happens Next?
-
1
Partner testing — blood or saliva sample, results in 1–2 weeks
-
2
Genetic counseling — available for in-depth discussion of your specific risks and options
-
3
Review your options — prenatal diagnosis or PGT if both parents are carriers
-
4
Ask questions — your care team is here for you at every step
Atlanta Perinatal Associates
Remember
✓ You are healthy. Being a carrier does not affect your health.
✓ Being a carrier is common — about 1 in 50 people carry this variant.
✓ You have options. We will walk through every one with you.
✓ You are not alone. We are your partners in care.
Questions are always welcome.
Atlanta Perinatal Associates