Levels of cerebrospinal fluid nerve-growth factor differ in infantile autism and Rett syndrome.

Autism and Rett syndrome (RS) are both developmental disorders of unknown origin. Autism is a behaviourally defined syndrome. RS, which affects girls only, is characterized by a profound learning disability following early normal development, with a consistent cluster of clinical features. Differentiation of RS from infantile autism in the very early stages of the disorders is not always easy. Both syndromes still lack discriminative laboratory markers for accurate diagnosis and differentiation. We decided to compare the CSF nerve-growth factor (NGF) levels of children with infantile autism and children with RS using enzyme-linked immunosorbent assay (ELISA). Our findings of mainly normal CSF NGF in autism and low to negligible values in RS are in agreement with the different morphological and neurochemical findings (brain growth, affected brain areas, neurotransmitter metabolism) in the two syndromes. CSF NGF could be used as a biochemical marker for differentiation of patients with autism from those with RS.