ALTERNATE NAMES

Cerebroatrophic Hyperammonemia; MECP2 Related Disorder; RTS; RTT

DESCRIPTION

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.

DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM/ICD-10-CM CODING

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 RTT.

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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  Tremors;

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  Loss of speech;

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  Gait abnormalities;

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  Repetitive stereotypic hand movements;

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  Severe intellectual disability;

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  Microcephaly (abnormally small head);

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  Seizures;

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  Breathing abnormalities;

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  Disturbed sleeping patterns;

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  Scoliosis;

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  Impaired social interactions or social withdrawal;

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  Decreased mobility;

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  Muscle weakness;

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  Hand and foot deformities;

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  Rigidity;

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  Spasticity; and

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  Dystonia (involuntary muscle contractions).

ICD-9: 270.6

ICD-10: F84.2

PROGRESSION

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.

TREATMENT

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.

SUGGESTED PROGRAMMATIC ASSESSMENT*

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 RTT;

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  Additional clinical findings would show a characteristic decline or loss of previously attained developmental milestones (i.e., normal development for six to 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.

Suggested Listings for Evaluation:

DETERMINATION

LISTINGS

REMARKS

Meets

11.17

12.02

Mental dysfunction meeting the severity of these listings.

110.08

All claimants with clinical diagnostic criteria of RTT and abnormal molecular genetic testing of the MECP2 gene. (Positive genetic testing alone would not meet 110.08 B).

111.17

112.02

Mental dysfunction meeting the severity of these listings.

Equals