Neurogenetics Reference Lab · Teaching Example
- Panel
- SMA-targeted MLPA + SMN2 copy-number assay
- Report ID
- TEACH-0006
- Indication
- Hypotonia, areflexia, tongue fasciculations at age 4 months; newborn screening flag for SMA.
- Specimen
- Peripheral blood, EDTA · Received 2026-04-01
- Reported
- 2026-04-04
- Methodology
- SMN1/SMN2 MLPA (gold-standard for SMN copy number; short-read NGS cannot distinguish SMN1 from the highly homologous SMN2).
Patient (anonymized teaching example)
Age 4 months · Female · European ancestry
Clinical: Failed newborn SMA screen. On exam at 4 months: hypotonia, head lag, absent deep tendon reflexes, tongue fasciculations. Family wants urgent confirmation for treatment initiation.
Reportable Variants
| Gene | Variant | Zygosity | Condition (Mode) | Origin | Classification |
|---|---|---|---|---|---|
Interpretation
MLPA detected a — the most common SMA-causing genotype, present in ~95% of clinically confirmed SMA patients. is 2. Both parents are (one SMN1 copy each). Classification: Pathogenic. This result is diagnostic for autosomal-recessive spinal muscular atrophy. SMN2 copy number of 2 is associated with severe (type I / type II) disease.
Recommendations
- •URGENT referral for SMA-modifying therapy. Treatment options include nusinersen (intrathecal), risdiplam (oral), and onasemnogene abeparvovec (gene therapy) — choice depends on age, weight, and antibody status.
- •Multidisciplinary care: neurology, pulmonology, nutrition, PT/OT.
- •Confirm SMN2 copy number (here = 2) — this is the key prognostic modifier and informs urgency of treatment initiation.
- •Genetic counseling for parents (obligate carriers). 25% recurrence risk for future pregnancies; carrier testing for at-risk relatives.