Four young boys with neonatal onset of encephalopathy, a progressive course, and MECP2 mutations are reported from the University of Alabama, Birmingham, AL Symptoms suggestive of Rett syndrome included failure to thrive, respiratory insufficiency, microcephaly, hypotonia, movement disorder, with myoclonic, dyskinetic, and choreiform patterns, and repetitive face scratching or nose rubbing stereotypies. MECP2 mutations, characteristic of girls with Rett syndrome, are previously reported in 11 boys with progressive encephalopathy, 7 having affected sisters. The authors report 4 de novo male cases, 3 of whom died at 14 to 27 months of age. Details of the 11 previously published male patients are tabulated, 10 of whom died in infancy. 
COMMENT. Young boys presenting with early progressive encephalopathy, respiratory insufficiency, movement disorder, seizures, or changes in muscle tone should be tested for MECP2 pathology and a possible diagnosis of Rett syndrome. Molecular confirmation is important in defining the cause and prognosis of this progressive encephalopathy and in providing genetic counseling.