Association of phenotypic abnormalities of Down syndrome with an imbalance of genes on chromosome 21.

The phenotype of the brain in Down syndrome is different from that of a normal child both in its reduced size and altered gyral configuration. Underlying the mental retardation are neuronal abnormalities, including alterations of cortical lamination, reduced dendritic ramifications, and diminished synaptic formation. However, cholinergic enzymes such as… CONTINUE READING