Single-dose injection of onasemnogene abeparvovec gene therapy, billed per treatment

Onasemnogene abeparvovec-xioi (Zolgensma) is an adeno-associated virus vector-based gene therapy that delivers a functional copy of the SMN1 gene to motor neurons, addressing the underlying genetic defect in spinal muscular atrophy (SMA). This code captures the per-treatment administration of this one-time intravenous infusion, which is among the most expensive single-dose therapies in clinical use. It is distinct from ongoing SMA pharmacotherapy and represents a single, definitive gene replacement intervention.

This code applies when onasemnogene abeparvovec is administered as a one-time IV infusion, typically in pediatric patients under 2 years of age with biallelic SMN1 mutations (SMA Type 1 or presymptomatic SMA confirmed via newborn screening). Documentation supporting this code should include the confirmed SMA diagnosis (e.g., ICD-10 G12.0), genetic testing confirming SMN1 deletion/mutation, patient age and weight at time of infusion, and prior authorization approval, which is universally required given the drug's cost (~$2+ million per treatment). Administration typically occurs in a hospital outpatient or infusion center setting.

• Prior authorization is mandatory for virtually all payers; ensure PA documentation is retained and that the authorization number is included on the claim to prevent denial.
• Do not confuse with nusinersen (Spinraza) administration, which is an intrathecal injection billed separately and used for ongoing SMA management rather than one-time gene therapy; these drugs have distinct mechanisms, routes, and coding pathways.
• Bill the appropriate infusion administration code (e.g., 96413 for initial chemotherapy/complex drug infusion) in addition to this drug code; verify payer-specific bundling rules, as some payers may require facility and professional claims to be coordinated carefully given the single-episode nature of the treatment.