A case of RAI-related Smith-Magenis sydrome with obesity and small-stepped and robotic gait

The patient was born at term (40+ weeks gestation) following an uneventful pregnancy marked by reduced fetal movements. Muscular hypotonia was observed early, prompting initiation of physical therapy at 6 months of age. Speech development was delayed, with the first words emerging at approximately 18 months. Despite normal social interactions, there was noted reduced motivation.
Neurological examination revealed a gait described as small-stepped and robotic. Ocular examination showed left predominant exotropia since age 4. Brain MRI identified a paramedian left cerebellar arachnoid cyst measuring approximately 1.5 x 1.0 x 4.0 cm.
Neurocognitive assessment revealed a mild learning disability with an IQ of 75. Educational attainment included completion of the Hauptschule. The patient experienced sleep disturbances and significant hyperphagia leading to obesity, with a recorded body weight of 154 kg and BMI of 48.6 kg/m² at age 17.