Program Operations Manual System (POMS)
TN 10 (01-14)
DI 23022.231 Marshall-Smith Syndrome
COMPASSIONATE ALLOWANCE INFORMATION
Marshall-Smith Syndrome (MSS) is a genetic disorder characterized by abnormal bone and skeletal maturation, failure to thrive, respiratory difficulties, dysmorphic facial features, and moderate to severe developmental delay with absent or limited speech and unusual behavior. The exact cause of this disorder is unknown, and no specific chromosomal abnormalities have been identified. This condition is not the same as Marshall syndrome, which is a different genetic syndrome.
DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM CODING
Diagnostic testing: Imaging studies showing abnormal bone maturation, or minor brain abnormalities such as hypoplasia of the corpus callosum.
Physical findings: Short stature; kyphoscoliosis; nontraumatic fractures; failure to thrive; developmental delay or intellectual disability; respiratory compromise; unusual facies with wide and prominent forehead (frontal bossing); protruding and widely spaced eyes (proptosis); depressed nasal bridge; small upturned nose; and micrognathia (abnormally small jaws).
ONSET AND PROGRESSION
MSS abnormalities usually begin before birth. Symptoms in children vary in degrees of severity. Mortality is associated with respiratory complications caused by structural problems in the respiratory tract and complications from pneumonia. Children surviving infancy may have developmental delays and intellectual impairment.
There is no cure for MSS. Treatment is symptom specific and supportive. Children with MSS are treated with aggressive management of early respiratory and feeding difficulties.
SUGGESTED PROGRAMMATIC ASSESSMENT*
Suggested MER for evaluation:
Clinical history and examination that describes the diagnostic features of the impairment.
Genetic testing reports for NF1X mutation.
Imaging of the skeleton showing accelerated osseous maturation.
Suggested Listings for Evaluation:
Listing-level severity must be documented; may also need to evaluate under the Musculoskeletal and Mental body systems.
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* Adjudicators may, at their discretion, use the Medical Evidence of Record or Listings suggested to evaluate the claim. However, the decision to allow or deny the claim rests with the adjudicator.