ICD-10-CM 2027
ICD-10 code for Rett's disease or syndrome
From the official ICD-10-CM alphabetic index entry “Rett's disease or syndrome”. Page updated September 29, 2026.
About coding Rett's disease or syndrome
The ICD-10-CM code for Rett's disease or syndrome is F84.2 (Rett's syndrome).
Within F84 (pervasive developmental disorders), F84.2 is specifically for Rett's syndrome. Related codes cover Autistic disorder (F84.0), other childhood disintegrative disorder (F84.3), Asperger's syndrome (F84.5), other pervasive developmental disorders (F84.8) and pervasive developmental disorder, unspecified (F84.9).
Don't report F84.2 together with the conditions in its Excludes1 note: Asperger's syndrome (F84.5), Autistic disorder (F84.0) and Other childhood disintegrative disorder (F84.3).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
Don't confuse with (Excludes1 for F84.2)
Common questions about Rett's disease or syndrome ICD-10 codes
What is the ICD-10 code for Rett's disease or syndrome?
- F84.2 — Rett's syndrome.
Is F84.2 billable?
- Yes. F84.2 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can F84.2 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict F84.2 as a principal diagnosis.
Is F84.2 a CC or MCC?
- F84.2 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.