This policy is designed to address medical guidelines that are appropriate for the majority of individuals with a particular disease, illness, or condition. Each person's unique clinical circumstances may warrant individual consideration, based on review of applicable medical records.

SMN1 exon 7 deletion may be considered medically necessary when the following criteria are met:

• Genetic Counseling:
  • Pre and post-test genetic counseling by an appropriate provider; and
• Previous Genetic Testing:
  • No previous genetic testing of the SMN1 gene; and
• Diagnostic Testing for Symptomatic Individuals:
  • Child with hypotonia and weakness (generally symmetrical, proximal more than distal); or
  • Young adult (through twenties) onset of weakness more severely affecting the legs than arms (may be associated with frequent falls, difficulty with stairs); and
  • No obvious signs of different neurological disorder; or
• Carrier Screening:
  • SMN1 exon 7 deletion testing is not suitable for carrier screening. SMN1/SMN2 dosage analysis is necessary (see below); or
• Prenatal Testing: 
  • Both parents are carriers of an SMA mutation (at least one of which is an exon 7 deletion mutation). 

SMN1/SMN2 dosage analysis may be considered medically necessary when the following criteria are met:

•  Genetic Counseling:
  • Pre and post-test genetic counseling by an appropriate provider; and
• Previous Testing:
  • No previous genetic testing of the SMN1 gene in the carrier testing setting; or
  • Non-diagnostic results from SMN1 exon 7 deletion testing (not homozygous SMN1 deletion) in the diagnostic setting, and
•  Diagnostic Testing for Symptomatic Individuals:
  • Index of suspicion for SMA remains high despite non-diagnostic SMN1 exon 7 deletion testing based on:
    • Proximal greater than distal weakness; and
    • Normal creatine kinase (CK); and
    • Neurogenic EMG; or
• Carrier Screening:
  • Be of reproductive age, and
  • Have potential and intention to reproduce, or
  • Have a reproductive partner who is a carrier of SMA; or
  • Have a reproductive partner with SMA; or
•  Prenatal Testing:
  • SMN1/SMN2 Dosage Analysis is not suitable for preimplantation/prenatal diagnosis. Other forms of SMA testing may be indicated based on the mutation status of parents. See those sections for guidance.

SMN1 known familial mutation analysis may be considered medically necessary when the following criteria are met:

• Genetic Counseling:
  • Pre and post-test genetic counseling by an appropriate provider; and
• Previous Genetic Testing:
  • No previous genetic testing for known SMN1 family mutation(s); and
• Diagnostic Testing for Symptomatic Individuals:
  • Known family SMN1 point mutation(s) in biological relative; or
•  Carrier Screening:
  • Known family SMN1 point mutation(s) in biological relative.

SMN1 sequencing may be considered medically necessary when the following criteria are met:

• Genetic Counseling:
  • Pre and post-test genetic counseling by an appropriate provider; and
• Previous Genetic Testing:
  • SMN1 exon 7 deletion testing did not reveal a homozygous SMN1 deletion and SMN1/SMN2 gene dosage analysis identified a single copy of SMN1 exon 7 in the diagnostic setting; or
  • SMN1/SMN2 gene dosage analysis did not confirm carrier status of an exon 7 deletion in the carrier testing setting; and
• Diagnostic Testing for Symptomatic Individuals:
  • Individual suspected to have compound heterozygous SMA based previous test results; and
  • Proximal greater than distal weakness; and
  • Normal creatine kinase (CK); and
  • Neurogenic EMG; or
• Carrier Screening:
  • Have one of the following increased risk indication with a noninformative SMN1/SMN2 gene dosage analysis result:
    • Have a reproductive partner who is a carrier of SMA; or
    • Have a reproductive partner with SMA; or
• Prenatal Testing:
  • Embryos or At-Risk Fetuses:
    • SMN1 full gene sequencing is not generally necessary for preimplantation/prenatal diagnosis as parental mutation status should have already been determined with SMN1 exon 7 deletion testing (section 1-A) +/- SMN1 known familial variant analysis (section 1-C).

SMN2 gene copy analysis is considered experimental/investigational and therefore non-covered. Genetic testing is not approved for SMN2 gene copy analysis for the purposes of predicting SMA prognosis.

Experimental/Investigational (E/I) services are not covered regardless of place of service.

SMA testing is typically an outpatient procedure which is only eligible for coverage as an inpatient procedure in special circumstances, including, but not limited to, the presence of a co-morbid condition that would require monitoring in a more controlled environment such as the inpatient setting.

Services that do not meet the criteria of this policy will not be considered medically necessary. A network provider cannot bill the member for the denied service unless: (a) the provider has given advance written notice, informing the member that the service may be deemed not medically necessary; (b) the member is provided with an estimate of the cost; and (c) the member agrees in writing to assume financial responsibility in advance of receiving the service. The signed agreement must be maintained in the provider’s records.

Services that do not meet the criteria of this policy will be considered experimental/investigational (E/I). A network provider can bill the member for the experimental/investigational service. The provider must give advance written notice informing the member that the service has been deemed E/I. The member must be provided with an estimate of the cost and the member must agree in writing to assume financial responsibility in advance of receiving the service. The signed agreement must be maintained in the provider’s records.

• Link to References