As of November, 2013:
Tier 2 CPT code 81404:
FSHMD1A (facioscapulohumeral muscular dystrophy 1A) [evaluation for abnormal alleles, and/or characterization of haplotype(s)]
This policy is based on a search of the MEDLINE database through June 2013. Literature that describes the analytic validity, clinical validity, and clinical utility of testing for facioscapulohumeral muscular dystrophy (FSHD) was sought.
Analytic validity (technical accuracy of the test in detecting a mutation that is present or in excluding a mutation that is absent)
According to one laboratory, Southern blotting diagnostic methods enable the identification of FSHD1 in about 95% of cases. (6)
Clinical validity (diagnostic performance of the test [sensitivity, specificity, positive and negative predictive values] in detecting clinical disease)
According to a large reference laboratory, the identification of a characteristic 4q35 deletion is more than 90% specific for the disease. (7)
There are reports of a correlation between the degree of the mutation of the D4Z4 locus and the age at onset of symptoms, age at loss of ambulation, and muscle strength as measured by quantitative isometric myometry. Some reports in the literature describe individuals with a large contraction of the D4Z4 locus having earlier-onset disease and more rapid progression than those with smaller contractions of the D4Z4 locus, although other reports have not been able to confirm a correlation between disease severity and degree of D4Z4 contraction mutations. (3)
On average, de novo mutations are associated with larger contractions of D4Z4 compared to the degree of D4Z4 contraction mutations observed segregating in families, and individuals with de novo mutations tend to have findings at the more severe end of the phenotypic spectrum. (3)
Clinical utility (how the results of the diagnostic test will be used to change management of the patient and whether these changes in management lead to clinically important improvements in health outcomes)
The clinical utility for patients with suspected FSHD depends on the ability of genetic testing to make a definitive diagnosis and for that diagnosis to lead to management changes that improve outcomes. There is no direct evidence for the clinical utility of genetic testing in these patients as no studies were identified that described how a molecular diagnosis of FSHD changed patient management.
However, for patients who are diagnosed with FSHD by identifying a D4Z4 contraction mutation, the clinical utility of molecular genetic testing for FSHD includes:
- Establishing the diagnosis and initiating/directing treatment, such as evaluation for physical therapy and the need for assistive devices, assessment for hearing loss, ophthalmologic examination for the presence of retinal telangiectasias and continued ophthalmologic surveillance, and possible orthopedic intervention;
- Distinguishing from other disorders that are similar clinically to FSHD, especially the limb-girdle muscular dystrophies and scapuloperoneal muscular dystrophy syndromes;
- Avoidance of a muscle biopsy in the majority of cases.
Treatment after a confirmed diagnosis of FSHD includes physical therapy and rehabilitation, exercise, pain management, ventilator support for those with hypoventilation, therapy for hearing loss, orthopedic intervention (ankle/foot orthoses; surgical fixation of the scapula to the chest wall to improve range of motion) and ophthalmologic management including lubricants or taping the eyes shut at night for exposure keratitis.
For those with a confirmed diagnosis of FSHD, the following surveillance applies (3) (8):
- Regular assessment of pain;
- Routine screening for hypoventilation in those with moderate to severe disease, and yearly forced vital capacity (FVC) measurements for all affected individuals who are wheelchair bound, have pelvic girdle weakness and superimposed pulmonary disease, and/or have moderate to severe kyphoscoliosis, lumbar hyperlordosis, or chest wall deformities;
- Hearing loss assessment in children as routinely performed as part of school-based testing. In severe infantile onset forms of FSHD, hearing screens are important as hearing loss can result in delayed language acquisition. Adults should have a formal hearing evaluation based on symptoms;
- Annual dilated ophthalmoscopy in childhood is indicated. In adults, a dilated retinal exam should be performed at the time of diagnosis, and if vascular disease is absent, follow-up exams are only necessary if visual symptoms develop.
Most individuals diagnosed with FSHD have a parent with clinical findings of FSHD and one D4Z4 allele with a contraction mutation (70-90% of individuals with FSHD), although 10-30% of probands with FSHD have the disorder as a result of a D4Z4 de novo contraction mutation. (3) Evaluation of at risk relatives may determine that they may be affected but escaped previous diagnosis because of a milder phenotypic presentation. However, for this population, no evidence was identified that compared outcomes in family members tested for genetic mutations compared to family members not tested for genetic mutations, and conclusions cannot be made on whether genetic testing of asymptomatic family members of a patient with known FSHD improves outcomes.
Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant disease that typically presents before the age of 20 years with weakness of the facial muscles and the scapular stabilizer muscles; however, atypical presentations occur. The clinical course is usually of slowly progressive weakness, although the severity is highly variable. Approximately 95% of individuals with FSHD have contraction mutation of the D4Z4 locus.
The clinical utility of genetic testing for FSHD is that it leads to a definitive diagnosis and can distinguish FSHD from other myopathies, with possible avoidance of a muscle biopsy. Changes in clinical management include supportive management involving physical therapy and rehabilitation, exercise, pain control and orthopedic interventions. Other issues include increased surveillance for potential pulmonary, ophthalmologic, and auditory problems related to FSHD. Therefore, genetic testing for FSHD may be considered medically necessary when a presumptive diagnosis of FSHD has been made based on clinical signs. Genetic testing for facioscapulohumeral muscular dystrophy is considered experimental, investigational and/or unproven for all other indications.
Practice Guidelines and Position Statements
In a report from the 171st European Neuromuscular Centre International Workshop Standards of Care and Management of FSHD held in January 2010, it is stated that when a physician concludes facioscapulohumeral syndrome based on clinical findings, the odds are in favor of FSHD, and genetic testing is the preferred diagnostic choice. (9)
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