ICD-10 Code F84.2 – Rett’s syndrome (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code F84.2 – Rett’s syndrome
What it is
F84.2 identifies Rett syndrome, a neurodevelopmental disorder that mainly affects girls and causes loss of previously acquired skills. Use it when the record documents this specific syndrome.
Clinical signs
Typical findings include early normal development followed by regression, loss of purposeful hand use, and repetitive hand movements. Clinical features vary; refer to documentation.
When to use this code
Use F84.2 when the provider diagnoses Rett syndrome or clearly documents it as the reason for evaluation. It may appear in pediatric neurology, developmental, or genetic assessments. If the note only says developmental delay or autism-like behavior, check documentation before coding.
Do not use for
Do not use this code for nonspecific developmental delay, autism spectrum disorder, or other neurodevelopmental conditions without a documented Rett syndrome diagnosis. Check documentation.
Coding tip
Code F84.2 only when Rett syndrome is explicitly stated or clearly established in the record.