F84.2Rett's syndrome

F84.2 is the ICD-10-CM diagnosis code for Rett's syndrome. It belongs to category F84 (pervasive developmental disorders), block F80-F89 (pervasive and specific developmental disorders) and chapter 5 (mental, Behavioral and Neurodevelopmental disorders). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

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.

In MS-DRG v44.0, it is part of the grouping logic for DRG 056 (Degenerative Nervous System Disorders with MCC, relative weight 2.2655) and DRG 057 (Degenerative Nervous System Disorders without MCC, relative weight 1.2838), in MDC 01 (Diseases and Disorders of the Nervous System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 330.8 (other specified cerebral degenerations in childhood).