F84.2 Rett's syndrome

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Excludes1 (never code together)

• Asperger's syndrome (F84.5)
• Autistic disorder (F84.0)
• Other childhood disintegrative disorder (F84.3)

Applies from F84 Pervasive developmental disorders

Code also

• any associated medical condition and intellectual disabilities

Risk adjustment (HCC)

• RxHCC V08: HCC 133 — Anxiety and Other Psychiatric Disorders

MS-DRG index

Defines the logic of DRG(s) 056-057 in MDC 01.

Approximate ICD-9-CM (GEMs)

• 330.8 Other specified cerebral degenerations in childhood (approximate)

Code annotations containing back-references to F84.2

Back-references to F84.2

• Type 1 Excludes: F84.3 Other childhood disintegrative disorder ("Rett's syndrome (F84.2)")

Back-references to F84

• Type 2 Excludes: F80.1 Expressive language disorder ("pervasive developmental disorders (F84.-)")
• Type 2 Excludes: F80.2 Mixed receptive-expressive language disorder ("pervasive developmental disorders (F84.-)")
• Type 2 Excludes: F90 Attention-deficit hyperactivity disorders ("pervasive developmental disorders (F84.-)")
• Type 2 Excludes: F91 Conduct disorders ("pervasive developmental disorders (F84.-)")
• Type 2 Excludes: F94.0 Selective mutism ("pervasive developmental disorders (F84.-)")
• Code Also: G93.45 Developmental and epileptic encephalopathy ("pervasive developmental disorders (F84.-)")
• Use Additional: Q87.87 Hao-Fountain Syndrome ("pervasive developmental disorders (F84.-)")
• Code Also: QA0 Neurodevelopmental disorders related to specific genetic pathogenic variants ("pervasive developmental disorders (F84.-)")
• Code Also: Z15.1 Genetic susceptibility to epilepsy and neurodevelopmental disorders ("pervasive developmental disorders (F84.-)")
• Type 1 Excludes: Z55 Problems related to education and literacy ("disorders of psychological development (F80-F89)")
• Code First: Z91.83 Wandering in diseases classified elsewhere ("autism or pervasive developmental disorder (F84.-)")

Diagnosis Index entries for F84.2

• Rett's disease or syndrome

Nearby codes

• F84 Pervasive developmental disorders
• F84.0 Autistic disorder
• F84.2 Rett's syndrome (this code)
• F84.3 Other childhood disintegrative disorder
• F84.5 Asperger's syndrome
• F84.8 Other pervasive developmental disorders
• F84.9 Pervasive developmental disorder, unspecified