A 2-year-old girl developed normally until 14 months of age, then lost spoken words and purposeful use of her hands. She now performs continuous midline hand wringing movements. Her head circumference has fallen from the 50th to below the 3rd percentile. Gait is broad-based and unsteady. Which is the most likely diagnosis?

• A Autism spectrum disorder
• B Childhood disintegrative disorder
• C Spastic diplegic cerebral palsy
• D Rett syndrome ✓

Explanation

Rett syndrome, caused by MECP2 mutation, affects almost exclusively girls and shows normal development for 6 to 18 months followed by loss of speech and purposeful hand use, acquired microcephaly, midline stereotypic hand wringing, and apraxic gait. Autism may show regression and repetitive behaviors, but head growth is normal or macrocephalic and hand use is preserved, which kills that distractor. Childhood disintegrative disorder involves regression after age 2 years across multiple domains without microcephaly.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.