Ataxia, developmental delay and an extensive neuronal migration abnormality in 2 siblings.

Two siblings with developmental delay and a non-progressive cerebellar ataxia are described. The electroencephalograms in both children showed a rather unusual pattern of high amplitude 10-12/s rhythms maximal anteriorly, while extensive neuronal migration abnormalities were apparent on Magnetic Resonance scans. There were no dysmorphic features, metabolic abnormalities, chromosomal defects or evidence of prenatal environmental toxins. It is considered that these siblings have an autosomal recessive neuronal migration defect which has not previously been reported.