What is the difference between angelman syndrome and down syndrome?

Neurodevelopmental : Disorders like AS & DS that cause Intellectual Disability differ in etiology, signs & symptoms & Neurobehavioral profiles including motor, language, cognitive & social/ adaptive skills. The genetic accident that causes DS gives a fetus 3 copies of Chromosome 21; a fetus with AS may lack a maternal UBE3A gene, have 2 copies of the gene from dad, or only dad's gene is active at Chr.15 q11.2-q13.