RETT
SYNDROME (RTT) |
ALTERNATE NAMES
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MECP2 Related Disorder; RTT; RTS; cerebroatrophic hyperammonemia
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DESCRIPTION
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Rett
syndrome
(RTT), one of the MECP2 gene-related disorders, is a progressive neurologic disease in
girls characterized by normal birth and apparently normal psychomotor development
during the first six to 18 months of life. The girls then enter a short period of
developmental stagnation followed by rapid regression in language and motor skills.
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DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM/ICD-10-CM
CODING
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Diagnostic testing:
The diagnosis of RTT rests on clinical diagnostic criteria established for the syndrome
and/or molecular testing of the MECP2 gene. Molecular genetic testing identifies MECP2
mutations in approximately 80% of females with Rett syndrome.
Physical findings: RTT is characterized by:
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Rapid developmental regression in infancy;
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Loss of purposeful hand movements;
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Screaming fits and inconsolable crying;
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Bruxism (teeth grinding);
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Repetitive stereotypic hand movements;
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Severe intellectual disability;
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Disturbed sleeping patterns;
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Impaired social interactions or social withdrawal;
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Hand and foot deformities;
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Dystonia (involuntary muscle contractions).
ICD-9: 270.6
ICD-10: F84.2
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PROGRESSION
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Females with RTT may survive into adulthood, but in a very dependent state. The incidence
of sudden, unexplained death is significantly higher than in controls of similar age
and may in part be caused by the higher incidence of longer corrected QT intervals,
T-wave abnormalities, and reduced heart rate variability.
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TREATMENT
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Currently there is no cure for RTT. Management is mainly symptomatic focusing on optimizing
the individual’s abilities and providing psychosocial support for the family.
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SUGGESTED PROGRAMMATIC ASSESSMENT*
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Suggested MER for
Evaluation:
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Molecular genetic testing with sequence analysis of the MECP2 gene on the X chromosome
will identify 80% of individuals with Rett syndrome;
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Additional clinical findings would show a characteristic decline or loss of previously
attained developmental milestones (i.e., normal development for 6-18 months, followed
by loss of milestones); and
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A description of characteristic motor findings (repetitive hand movements, toe walking
or unsteady, wide-based, stiff-legged gait) and severely impaired expressive language.
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Suggested Listings for
Evaluation: |
DETERMINATION |
LISTINGS
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REMARKS
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Meets |
11.17 |
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12.02
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Mental dysfunction meeting the severity of these listings. |
110.08
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All claimants with clinical diagnostic criteria of Rett syndrome and abnormal molecular
genetic testing of the MECP2 gene. (Positive genetic testing alone would not meet
110.08B).
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111.17
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112.02
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Mental dysfunction meeting the severity of these listings. |
Equals |
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* Adjudicators may, at their discretion, use the Medical Evidence of Record or the
listings suggested to evaluate the claim. However, the decision to allow or deny the
claim rests with the adjudicator.
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